Ed. 04.12.2018

07.05.2013

I finished assembling my first HF-UM using GI-7B metal-ceramic lamps with transformerless power supply according to the scheme of the respected I. Goncharenko. Photos of the assembly process are posted in.

04.01.2015

After analyzing the information on the forums regarding the issues of constructing transformerless power supplies, I decided to remake the original version of my power supply, which used 6 capacitors of 330 μFx400V each. With a load current of more than 300 mA, the anode voltage drop was significant... Actually, according to the recommendations of I. Goncharenko, the load capacity of the second stage of the power supply was exactly 300 mA, because the total capacitance of the capacitors in each arm was about 165 μF.

Added 12/08/2016

As it turned out later, the voltage drop was associated with a drop in voltage in the network... However, in any case, multiplying by 4 is not enough for GI-7B. It is better to multiply by 6 or 8.

Now, in the first stage there will be two 330 µFx400V capacitors in the shoulder (to separate the currents), in the second stage there will be 4 680 µFx400V capacitors. As a result, the expected load capacity of the b/p will have to increase to 600mA.

Also, I plan to separate the b/p from the lamp block with a heat shield made of fiberglass.

06.01.2015

The amplifier conversion is complete. Posted new photos.

In addition to reworking the power supply (here is the file for the Electronics Workbrench Version 5.12 modeler), I also replaced the anode choke. I made a copy of the Ameritron throttle. A ceramic tube with a diameter of 26.5 mm with a wall thickness of 2.6 mm and a winding wire of 0.355 mm over varnish was used. The inductance of the inductor was 200 μH. The old choke, made on a fluoroplastic rod with a diameter of 14 mm using PELSHO-0.56 wire, had an inductance of only 40 μH. The first resonance of the new choke is at a frequency of 6.5 MHz, the second at a frequency of about 12.6 MHz...

I calibrated the anode current meter using a reference milliammeter at 500 mA.

Amplifier operating data: at an input signal level of 30W, the equivalent output is 300W at a current of 440mA. Measured on the 40m range. Unfortunately, I have not yet measured the anode voltage drop. According to, after reworking the b/p, the anode should not drop below 1200V at a current of up to 1A. In principle, earlier, with the same anode, I easily pumped each of the lamps up to 200W at a current of 300mA, so for two lamps at a current of 600mA, the output power can reach 400W. However, I don’t see much point in this, because... The anode voltage is initially low for these lamps...

08.01.2015

Yesterday I noticed one unpleasant moment in the operation of the amplifier. The input did not want to be properly coordinated with the transceiver through an external P-circuit and, most importantly, after 20 seconds. in the key-press mode, the anode current began to increase and the output power gradually dropped to 200W. They suggested (R2AC) that the problem could be in the input transformer on ferrite tubes... Tubes from the monitor cable with semi-circular ends were installed. I read somewhere on the forum that they are not suitable for such purposes and there are tubes with straight ends - they are more suitable... Unfortunately, only one set of such ferrite was available and it was already used in the GU-50 - I didn't take pictures...

Conducted laboratory work with several types of ferrites available and different numbers of turns in the windings. I checked the input RF transformer in the PA and it turned out that there were three turns in all three windings. I unwinded one turn from the primary winding and measured the input resistance of the amplifier in transmit mode, connecting the AA330-M analyzer to the input. The resistance turned out to be 62 Ohms on the 40m range. After this, the amplifier input was in perfect agreement with the transceiver output and the effect of power reduction was no longer observed.

09.09.2015

I wrote about checking the linearity of an amplifier with a two-tone signal. my technique for measuring the IMD level, which I began to use a little later...

15.05.2016

Yesterday the result was obtained for the first time, and today it is fixed on the 40-30-20m ranges: 400W of useful power (current - 440mA) using a new voltage multiplier by 6. For this purpose, the old voltage multiplier by 4 was removed and a new one was connected, in test mode .

Material about multiplier options is posted.

Due to its dimensions, this multiplier does not fit into the existing case. The power supply will be made in a separate case, and I want to try to use the space freed up inside the amplifier to accommodate the input range P-circuits...

With a current of about 500mA, the multiplier does not heat up at all and does not create any noise.

The equivalent resistance has changed and the P-circuit will need to undergo some modification. I was afraid that I would flash the thinned KPI, but this has never happened yet.

21.05.2016

Today on air the guys suggested that PA somewhat changes the character of the sound of the signal from the transceiver. It was recommended to increase the quiescent current. The initial current was 40mA for two lamps (D815E + D815D). After replacing one of the zener diodes, the quiescent current became 100mA (D815E+D815V) and correspondents noted a noticeable improvement in signal quality. The level of out-of-band emissions is also normal (monitored on the Icom IC-7300 panorama).

Fortunately, it is better to assemble a bias circuit from zener diodes with a permissible current of 1A (letters A, B, C), however, there was only one zener diode with the letter “B” at hand.

When trying to transfer a metal-ceramic triode to a class close to class B, the signal distortions introduced by the PA become noticeable to on-air correspondents... Therefore, with an anode current of 440mA and a quiescent current of 100mA, the output power of my PA was 400W. Those. The efficiency turned out to be about 0.53. The power factor was 13. The quality factor of the P-circuit, which was redone, was 12.

Perhaps, using a similar 1.8 kV power supply using the GK-71 pentode, it would be possible to obtain a higher output power while maintaining signal quality, or a similar one with a lower anode current. Over time, I will definitely check this in practice!

After working on air for half an hour in leisurely dialogue mode, I noticed that the amplifier had warmed up and the fans were blowing warm air. This is understandable; 180 W of power is constantly consumed at the anodes at quiescent current. Also, from the point of view of energy saving, this is far from the optimal option. I had to make a circuit to lock the lamps during RX. I used an additional D817G zener diode (placed it in the gap between two working zener diodes, since it was convenient in design) and used a free pair of contacts of the REN29 input relay. The latter had to be “torn off” from the chassis by placing a textolite gasket between the chassis and the relay housing. Zener diodes D815 are installed on small radiators from a 40x15x35 corner, D817 is fixed between them on a textolite support plate without a radiator.

There was doubt about possible interference during switching and the ability of the relay winding insulation to withstand a potential difference of about 900V (relative to the contact group), which is the maximum value of this relay according to the passport. Fortunately, the fears were not confirmed. Switching works stably.

25.05.2016

Rebuilt the bias chain. Now a chain of three D815A and one D815B has been installed. The quiescent current is 90mA at a bias voltage of about 23V. The D817G zener diode, short-circuited at TX, is included in the circuit break. Since the calculated cathode current will not exceed 0.6A and the dissipated power will not exceed 3-4W - the zener diodes are installed without radiators. In addition, they are in the airflow field.

When the quiescent current of two lamps is about 90-100mA, the amplifier operates in class AB1 until the amplitude of the input signal (at the negative half-cycle) reaches the bias voltage level at the cathode and then in class AB2 (with the control grid current). According to some, the grid current(s) should not exceed 30% of the cathode current. According to others - 20...25%. It is advisable to control the grid current with a separate device, or to subtract the difference between the cathode current and the anode current. I assume that the guideline here can be the parameter of the maximum permissible power dissipation on the grid of one lamp - 7 W and if it is exceeded, the signal will deteriorate. Also, lumbago and even lamp failure are possible...

14.12.2016

Today I carried out laboratory work on measuring Ku by power and determining the grid currents of two GI-7B triodes, depending on the drive power. The results were tabulated.

Ueff, V	Pin,W	I,mA in "+"	I,mA in "-"	Ig,mA	Upit,V	Pout, W	Ku on power.	Efficiency
20.5	8.4	270	270	24	1780	200	23.8	0.42
26.5	14	340	340	56	1730	300	21.4	0.53
32	20.5	400	400	80	1700	380	18.5	0.56
36	26	440	440	100	1670	400	15.3	0.53

Explanations for the table:

Ueff - RF voltage from the transceiver, measured at the load equivalent with the VU-15 device (if you measure the voltage when connecting the P-circuit matching the transceiver output with the PA input, then the RF voltage level is lower);

Pin - drive power from the transceiver at the equivalent of 50 Ohm equal to Ueff x Ueff / 50;

I in "+" - current measured in the positive pole of a transformerless voltage multiplier by 6;

I in "-" - current measured in the negative pole of a transformerless voltage multiplier by 6;

Ig - current in the circuit “grid - zero volt point” (a 500mA milliammeter is connected to the gap with the positive pole to the “0V” point);

Upit - voltage at the poles of the multiplier, taking into account the drawdown depending on the load;

Pout - output useful power in the mode of pressing on the equivalent, measured by the SWR meter VEGA SX-200;

Ku - power gain - the ratio of output power to input power;

Efficiency = Pout / (Upit x I in "+"/1000)

According to my measurements, the grid current was about a quarter of the total current in either pole of the multiplier. By the way, in the case of a transformerless high-voltage source, from a safety point of view, there is no difference in which pole this device is turned on (in classic power supplies it is recommended to install a milliammeter in the negative circuit in order to have a minimum potential on the device relative to the amplifier housing), because . in any case, it will be at half the potential of the voltage multiplier relative to the chassis (housing).

It is also clearly noticeable that when the “cold” capacitance of the P-circuit has a lower value than at resonance, the grid current is less than the value that is set when setting the P-circuit to resonance. In the mode when the “cold” capacitance of the P-circuit has a greater value than in resonance, the grid current increases significantly.

Another interesting and understandable observation: if you turn off the mains voltage at the multiplier input and press the switch, the multiplier capacitors begin to discharge, the power and current in the multiplier poles begin to fall, and the grid current begins to increase. The increase continues until approximately 400mA (in my case) and obviously depends on the level of input drive. The increase in grid current occurs because as the anode voltage decreases, more and more electrons emitted by the cathode begin to be intercepted by the grid. In such a situation, you can easily exceed the maximum permissible power dissipation of the control grid, which will lead to overheating. Therefore, it is not recommended to discharge the power supply capacitances in this way...

The next step, I want to look at the current in the open circuit of the zener bias diodes, the amplitude and shape of the signal at the cathodes in order to determine the maximum voltage values ​​​​and calculate the instantaneous value of the power dissipated by the grids, taking into account the grid current. The grid current will have a pulsed intermittent form and therefore it will not be possible to calculate the dissipated power using the usual formulas, but it will be possible to determine its peak values... Also, by subtracting the value of the bias voltage from the amplitude value of the signal, it will be possible to see the potential difference at which the lamp already works in class AB2.

17.12.2016

Laboratory work on monitoring the currents of the anode, cathode and grid. Measuring instruments were included according to this diagram:

Because in the case of transformerless power supply, we have two absolutely identical poles in potential but different in sign - I recommend dividing the limiting resistors into both poles of the multiplier (only the positive pole is indicated in the figure) and limiting the discharge current in the event of a flash in the lamp or a short circuit in other circuits value 40-50A. Also, protection of the measuring head with back-to-back diodes and capacitance is shown only for the device lower in the figure. The arrows show the direction of current flow (from plus to minus).

The current in the positive and negative poles of the voltage multiplier is identical. The current in the zener diode circuit (cathode current) is the sum of the currents of the power source (anode) and the grid current (in the open circuit “grid - zero volt point”). So, with the cathode current of two lamps being about 500mA, the current in the power supply circuit was 420mA, and in the grid circuit - 84mA. The measurement was carried out at an output power of about 370W. If you monitor the current in the cathode circuit, you need to set the measuring device to the limit of 750mA or 1A. You can also add that when setting up the P-circuit, a dip in the anode current of about 15% is noticeable precisely by the meter in the power source circuit (anode current). The cathode current remains almost constant and depends on the level of input drive.

Leaving only the device for measuring the anode current and slightly increasing the drive, I looked at the signal at the output of the transceiver, at the input of the amplifier after the matching P-circuit, and at one of the windings of the filament transformer in the cathode circuit (the cathode is the connection point of the bias zener diode circuit). I assume that the asymmetry of the sine wave in the last photo is due to the fact that the load for the signal on the positive half-cycle is much higher than on the negative half-cycle (the lamp is locked). The negative half-wave of the signal shows an amplitude level of about 42V, despite the fact that the bias voltage at the cathode is +23V. Those. part of the half-cycle the lamp operates with grid current. Considering a grid current of 100mA and a difference amplitude of 19V, we obtain the instantaneous power dissipation value when setting the P-circuit to resonance- 1.9W for two lamps, which is significantly below the limit value.

I would like to draw your attention to the fact that when connecting an oscilloscope to an amplifier whose power supply is made using a transformerless circuit, it is strictly forbidden to allow the housing or probes of the device to come into contact with the chassis (housing) of the amplifier. Also, remember that the oscilloscope body and some control elements will be at high potential relative to ground and touching them is dangerous...

Some considerations regarding possible options for anode voltage and permissible anode currents when using one or two GI-7B lamps.

Consider the option with one lamp. Anode voltage - 1750V under load 300mA (multiplied by 6). The equivalent resistance of the lamp is about 2700 Ohm (according to I. Goncharenko’s formula). The power supplied to the anode is 525W. The efficiency of the triode according to the circuit with a common grid is 0.45...0.55. Let's take the maximum value. Then, the useful power will be about 290 W, and 235 W will be dissipated at the anode.

We pump the anode to a current of 400mA. Ua=1700V (with drawdown). Roe = 2000 Ohm (P-circuit on HF bends is easier to implement). Ppod.=680W. Rotd.=374W. 306 W will be dissipated at the anode. However, the emissivity of the cathode allows a maximum current of 0.6A. I assume that, taking into account the grid current, we will get a value close to the limit... That is. for a lamp this mode will be noticeably more difficult. If, however, the efficiency turns out to be minimal, the limiting mode for the anode will also be exceeded.

Hence, I would venture to suggest that at such an anode voltage, the middle between the two options considered will be optimal for one lamp...

Let's consider the following option - multiplying the network by 8. With a current consumption of 0.3A (anode current) and a voltage of about 2350V (under load), we supply more than 700W of power to the lamp, and the power dissipated by the anode will be almost the maximum value. However, the equivalent resistance of the lamp turns out to be more than 3700 Ohm and it will no longer be possible to implement a P-circuit on HF bends...

By increasing the anode current to 400mA, we will supply about 900W to the anode. The power dissipated by the anode will exceed the maximum permissible and the lamp will not last long. I assume that you won’t be able to get a good signal in this mode...

In this mode, two lamps could operate and the useful power would be about 500W. However, it is unlikely to be possible to implement a P-circuit with a quality factor of no more than 16 using HF bends.

The next mode is the anode current of two lamps is 600mA, the anode voltage under this load is 2300V. Roe=1800. Useful power is about 700 W and approximately a little less will be dissipated on the anodes. I assume that this will be the optimal maximum that two GI-7Bs are capable of.

Those. I mean that, in my opinion, when multiplying by 6, it is not worth achieving a power of more than 400W with a total anode current of two lamps of up to 450mA. If you use multiplication by 8, then the upper limit of useful power is about 700 W with an anode current of no more than 600 mA. In both cases, the P-circuit is completely implementable.

Of course, even when multiplied by 6, you can pump the anodes up to 600mA, however, this does not make sense, because the real increase in useful power will be insignificant... In addition, the grids will work in a more difficult mode. There is another point here - the cathode current will be about 800mA and the probability of failure of the zener diodes of the bias circuit increases...

(approx. 12/04/2018, at the moment I am using the amplifier with precisely these energy indicators, again, for experimental purposes)

As for the effect of these amplifier options on the air, relative to the standard transceiver power of 100W, a 400W power amplifier gives an increase of 1 point on the S-meter scale, 700W - a little less than one and a half points. Of course, when you demonstrate the difference between the power supplied from the transceiver (and it will be significantly lower than the standard 100W) and the output from the amplifier, the difference will be much more noticeable. For example, in my case, with a Ku power of about 16, this is 2 points on the S-meter scale.

02.01.2017

Happy New Year everyone!

After working with the amplifier for some time, I noticed that the ventilation system in this design does not cope with its function. I decided to redo the lamp suspension a bit. I abandoned the method of attaching the lamps to the mesh ring, while removing the duralumin plate with holes through which insufficient air from the fans passed to the anodes. In fact, the fan axes are located somewhat further from each other and, for good measure, the lamps should be moved apart by about a centimeter, but I won’t redo that.

I secured the lamps to the anodes, moved them a little closer to the fans, and moved them the same amount away from the fiberglass screen.

I think the thermal conditions of the lamps will now be more acceptable.

06.01.2017

One lamp died for a long time. The symptoms were as follows: the quiescent current increased by one and a half times, then the fuses in the power supply began to burn and the incandescent transformer became very hot. The filament resistance of one lamp was 0.6 Ohm, versus 2.7 Ohm for the other lamp.

RZ3DLL kindly donated a pair of GI-6Bs from storage, which were installed on the same day to replace the old lamps. I installed zener diodes of the bias circuit on small radiators, on the advice of older comrades.

An excellent opportunity has arisen to compare two models of lamps - GI-7B and GI-6B in operation on HF bends...

The switching of the filament windings of the TPP-268 transformer has been redone. Previously, the filament voltage was almost 14V (before one lamp failed). Now the filament voltage is 12.3V. Also, now I will be more careful about the bias voltage. I plan to set the quiescent current to 30-40mA per lamp.

07.01.2017

At the moment, the '76 lamps are undergoing training after a long period of storage. I’ll keep it under heat for 4-6 hours (with blowing), then an hour under a reduced anode voltage of 1240V (two stages from a multiplier of 6), then an hour under a low quiescent current, then an hour under anode voltage 1860V and, finally, an hour under rated quiescent current. After training the tubes, you can try to work on air with a slight boost and gradually bring the amplifier to the design power of 400W...

Laboratory work - GI-7B in section.

08.01.2017

With a current of 200mA in push mode, with 6W at the input, the output is 190W. Ku in power is more than thirty. The overall impression of the lamps is quite pleasant. The lamps do not overheat, the filament transformer is warm.

Another interesting observation. During training, in an hour of inactivity under the quiescent current, the latter increased from 78mA to 98mA. Currently, the quiescent current is about 60mA when turned on. During long-term operation it can grow to no more than 80mA for two lamps.

Note 09.12.2018

The bias circuit now contains three zener diodes D815A and one zener diode D815B, an additional “locking” zener diode is D817A (installed without a radiator). Quiescent current - 110mA.

03.12.2018

In the process of searching for a way to boost this amplifier to the desired 400W or more, I attempted to amplify the signal in several stages. It turned out to be a whole locomotive, with its own disadvantages, but completely having the right to exist. In addition, the method I found was interesting to me from a theoretical point of view and the opportunity to test the theory in practice.

The chain of signal transmission and amplification is as follows: from the mixer (IMD3 more than 50 dB) the signal goes to the amplifier (IMD3 about 42 dB at a power of less than 1 W), then to a circuit with a common cathode (PA1 in the figure below) and to 2xGI-6B ( PA2 in the figure below). With a current of 0.6A and 1700V anode voltage, the output amplifier produces a little more than 500W. Since the system is in the process of optimization, the final linearity parameters have not yet been obtained. The desired result is at least 30dB. But we can already say that the final amplifier degrades linearity very slightly, by approximately 2-3 dB, which once again confirms the fact that amplifiers with OS have a O 6dB greater linearity due to negative feedback. Of course, we are talking about the correctly selected operating mode and the optimal power received. Consequently, by feeding such an amplifier a sufficiently linear signal (36-38dB), it will be possible to obtain the coveted 34dB!

What is the difficulty in matching this system of two tube amplifiers? The final amplifier is made according to a circuit with common grids, which means that its input resistance depends on the frequency of the amplified signal, the anode current of the output lamps and the setting position of the P-circuit capacitors. In addition, without taking special measures (input range P-circuit with low quality factor), the input impedance of the amplifier with feedback changes from small (in this case, less than 50 Ohms) to infinitely large each signal period. I. Goncharenko wrote about this in detail. But, even having the input P-circuit of the final amplifier, we have two more - the VCS of each tube PA. In short, there are many unknowns in this equation...

I solve this problem in the following way. The first amplifier is tuned to the equivalent at the desired frequency at a power slightly lower than that expected for the subsequent drive of the final amplifier. The linearity of the signal is controlled. After this, we do not change the position of the P-circuit capacitors. If you connect an SWR meter into the gap between the amplifier and the equivalent, it should show a value close to unity. To switch nodes, I use standard cables about 0.9 m long. Next, we leave the SWR meter in the chain, and instead of the load equivalent we connect the input circuit of the final amplifier. The input matching circuit is a regular P-circuit with a low quality factor. First, we calculate the elements of this P-circuit using I. Goncharenko’s calculator.

Various sources for input P-circuits recommend Q values ​​in the range of 2-5. The lower the quality factor, the wider the frequency range, no additional matching will be required, but the input impedance will vary over a wider range, which is not good... For two GI-7(6)B, the approximate value of the input impedance will be about 35 Ohm. An example of calculating P-circuit elements with a quality factor of 5 for the 40m range:

When performing this unit, you can immediately install additional tuning capacitors, which will greatly facilitate further matching of circuits.

And finally, we move on to setting up the VCS of the final power amplifier (to the equivalent). Gradually, we bring the drive of the final amplifier to the design level. Of course, this will require reconfiguring the first amplifier as well. Having determined the preliminary settings for the capacitances of the final amplifier, we look at the SWR meter. Most likely, the readings will differ from one. Here you need to proceed to setting up the input P-circuit. In my case, it turned out that when 80W was supplied to the input, due to non-optimal matching, the signal power dropped by half, while the output of the final amplifier was about 400W. This indicated that the actual input impedance of the amplifier was lower than the calculated one. By adding capacitance to the input P-circuit from the lamp side, this imbalance was reduced and the SWR, by the way, approached the cherished value. With SWR values ​​close to unity, less drive power will be required than with poor matching, which will have a positive effect on the linearity of the signal. However, it cannot be reduced indefinitely, because this will lead to too high equivalent lamp resistance (Roe) of the PA1 amplifier; it will operate in an undervoltage mode due to the impossibility of transforming the resistance by standard elements of the P-circuit, etc.. For example, it is one thing to take from two fifty dollars according to a circuit with OK 60- 80W and completely different - 30-40W. In the latter case, the anode current will be too small, the standard cold capacity in the P-circuit will no longer be enough, it will not be possible to tune into resonance, etc. Switching to one tube will require reducing the anode voltage in order to obtain a normal Roe value, which is equivalent to actually reworking the amplifier...

My VEGA SX-200 SWR meter, installed in the gap between the amplifiers, allows you to measure the signal power passing through it. With sufficient matching, when the final amplifier is switched to amplification mode, the signal power should not differ significantly from the original one in the bypass mode. This will indicate that the previously configured intermediate amplifier PA1 to equivalent still sees a 50 Ohm load.

Despite its disadvantages (a large number of elements, the complexity of matching, inertia in terms of range tuning), this method of signal amplification has its advantages: a good power reserve for the drive of the final amplifier and a fairly high linearity of the signal. Previously, I was unable to obtain the same signal linearity parameters using transistor intermediate amplifiers...

To be continued...

HF power amplifier using two GI-7B lamps.

The amplifier using two GI-7B lamps is made according to the traditional design. Despite the fact that this lamp is designed to operate in a pulsed mode with anode modulation, when an excitation voltage is applied to the cathode of the lamp, and provided that only the left part of the anode-grid characteristics is used and additional measures are taken to match the cascades in resistance, it is possible to obtain satisfactory amplification linearity thanks to the effect of automatic current feedback.

Amplifier block.

The design of the amplifier is simple and does not require additional explanation. Figure 1 shows the electrical circuit diagram of the power amplifier unit. When designing the amplifier, an attempt was made to halve the equivalent resistance of the tubes at 29.7 MHz. Due to the fact that the resulting equivalent resistance of the lamps is quite high, the implementation of an inductor with a sufficiently high efficiency for the 10 m range is not possible. For this, two additional inductors were used - L2, L3. The input resistance of the cathode part of the amplifier at the maximum input signal is 43 Ohms, that is, close to 50 Ohms. However, contrary to popular belief, it is impossible to do without additional matching of the transceiver output stage with the input part of the amplifier.

Electronic vacuum devices represent a reactive load. This means that the input resistance of the lamp changes with a change in the excitation voltage level and, accordingly, with a change in the current flowing through the lamp. Those. at the maximum excitation voltage to the cathode, the negative half-wave of the signal, the minimum input resistance will be obtained, equal in this case to 43 Ohms. At the minimum voltage level, the input impedance of the lamp becomes extremely high, due to the quiescent current and the static parameters of the lamp. When the excitation signal level transitions to a positive half-wave, the input resistance of the lamp tends to infinity and will, in practice, be determined by the interelectrode capacitances and the frequency of the excitation signal.

Under such conditions, neither the use of matching transformers nor the automatic antenna tuners of modern transceivers are able to ensure matching of the transceivers with the output stages. Ignoring the need to take additional measures to match the transceiver with the amplifier leads to disruption of the linear operation of the transceiver output stage and the occurrence of an increased level of intermodulation distortion in the amplifier itself.

The main parameters of the tubes in the amplifier used:

• Lamp anode voltage, V ………………….. 2500
• Filament voltage, V………………………. 12.6... 13.2
• Maximum anode current of lamps, A…………..0.7
• Quiescent current, mA……………………………………50

High voltage power supply.

Figure 2 shows an electrical circuit diagram of a high-voltage power supply. The high-voltage power supply is made in a separate housing, with the minimum possible number of components. To limit the charging current of the filter capacitor, the switching is performed according to a two-stage scheme. High voltage is supplied from the power supply to the amplifier through coaxial connectors and coaxial cable. In order to increase safety, the cable shield is connected to the housing of the power supply and amplifier. The transformer power to operate only in SSB mode must be at least 1 kW.

If all types of modulation are intended to be used, the transformer power must be at least 1.5 kW. The output voltage of the power supply must be at least 2500 V at a delivered current of 50 mA (the amplifier's quiescent current). To reduce the risk of overvoltages, a load filter is installed at the output of the power supply associated with transient processes during operation of the amplifier and idling of the transformer. resistance R4. Short-term overvoltages can reach significant values ​​and cause an arc inside the lamp housing.

When commissioning the amplifier, it must be remembered that when installing a new lamp or if it has not been used for more than 3 months, it is necessary to start using it at a reduced generated power. Only after making sure that the tubes have restored vacuum and are stable should you switch to using the amplifier at maximum output power. Practice has shown that at first, when putting lamps into operation, it is recommended to use them for some time at approximately 50% of the output power. After which, gradually, if electrical breakdowns do not occur, the lamps are introduced at full rated power. The most crucial moment during this period is the moment of setting the output circuit to resonance using the KPI from the side of the lamp anodes, because this corresponds to the occurrence of the maximum total voltage at the anode. The lamp mode is monitored using a milliammeter in the power supply circuit of the control grids.

With resonance of the circuit and sufficient excitation power, a maximum amplitude of the alternating voltage at the anode occurs, and therefore the residual voltage at the anode becomes lower than the minimum permissible, resulting in the effect of interception of the electron flow by the lamp grids. This process is controlled by a timely increase in power transfer to the load using the output variable capacitor of the Pi circuit or by adjusting the excitation power of the amplifier. Both of these lead to a decrease in the alternating voltage at the anode and at the same time to a decrease in the current of the control grids.

Control circuit

The amplifier control unit is made according to a simplified design and does not have any special features. Figure 3 shows the electrical circuit diagram of the control unit. The +27V stabilizer is made on the KREN12A IC. To select the operating point of the lamps, a circuit with transistors VT2, VT3 was used. Fuse FU2 prevents damage to lamps and semiconductor devices in the cathode part of the lamps in the event of a discharge occurring inside the lamp body. Transistor VT4 contains a current protection circuit for the control grid of the lamp. The cutoff current is selected less than the maximum current of one lamp, since it is initially intended to use only the left side of the anode-grid characteristics of the lamps. This measure will also provide protection for both lamps due to grid currents.

The elements of the switching relay control circuit on transistor VT1 provide the necessary relay switching sequence. When the lamp grid current protection is triggered, the “reset” function is performed by turning off and then turning on the S3 “Standby” switch. Relay K1 reduces electrodynamic loads on circuit components and filament circuits of lamps. The delay is 1...2s. Neon lamps installed in switches are nonlinear elements that relieve overvoltages in circuits caused by transient processes.

Matching the amplifier with the load

The matching of the amplifier with the load does not differ from the standard one. An excitation signal is supplied to the amplifier input, approximately 30% of that required for full excitation. When the rotor of the Pi-circuit capacitor is fully inserted from the antenna side, by rotating the rotor of the Pi-circuit capacitor from the side of the lamp anodes, the resonance of the circuit system is found. Resonance is determined by the maximum current of the control grids. If there is no grid current or there is reverse current, then it is necessary to increase the excitation power.

Having received the maximum grid current, which should not exceed the maximum permissible, it is necessary to remove the capacitor plates from the antenna connection side, thereby supplying the power stored by the circuit to the load. In this case, it is necessary to control, by some method, the power supplied to the feeder. With the resulting maximum energy transfer to the feeder, the screen grid current will tend to a minimum. After which you can increase the excitation power again and repeat the procedure. This is done until the maximum anode current is obtained at a minimum control grid current and full power in the feeder.

Having determined the required maximum excitation power, you can set the ALC response threshold with resistor R7 located in the amplifier block.

Details

The following switching relays were used in this amplifier. Relays that were used in the high voltage power supply:

• K1 RPU-OUHL4 220/8A;
• K2 RPU-OUHL4 24-27/8A;

Relays that were used in the control circuit:

• K1 RES9 passport RS4.529.029-00;
• K2 RES22 passport RF4.523.023-00;
• KZ RPV2/7 passport RS4.521.952;
• K4 REV14 passport RF4.562.001-00;
• K5 RES9 passport RS4.529.029-00;

Basic parameters of an amplifier using two GI-7B lamps

When calculating, reference is made to the voltage at the anodes of the lamps (2500 V) and the quiescent current for two lamps (0.05 A). The linear amplifier was calculated using the "RF Amplifier's Developer 2001" program.

Results of calculating the parameters of the anode circuit of the amplifier for one lamp

• Anode voltage of the lamp, V ……………………………………………………………….. 2500
• Maximum permissible grid voltage, V ……………………………………………………………… 80
• Anode current of the lamp in carrier mode, A…………………………………………………… 0.35
• Lamp quiescent current, A……………………………………………………………………………………………… 0.025
• Anode current cut-off angle, degrees……………………………………………………….. 96.41
• Maximum anode current, A………………………………………………………………….. 1.034
• Maximum anode current of the first harmonic, A…………………………………………. 0.531
• Lamp gain at minimum residual voltage………………………………. 4,308
• Lamp mode voltage coefficient………………………………………………………….. 0.904
• Amplitude value of the alternating voltage generated by the anode of the lamp, V……… 2260
• Minimum residual voltage at the anode, V………………………………………….. 240
• Maximum amplitude of the total voltage at the anode, V………………………….… 4160
• Oscillatory power at the anode of the lamp, W…………………………………………….. 600.03
• Coefficient for SSB signal taking into account peak factor (p-4) ………………………………… 0.35
• Average oscillatory power of SSB signal, W………………………………………………………... 73.504
• Maximum power supplied to the anode, W………………………………………………………875
• Average lamp efficiency for SSB signal………………………………………………………..0.23
• Average power supplied to the anode, W………………………………………………………319.583
• Lamp efficiency…………………………………………………………………………………… 0.686
• Maximum power dissipated at the anode, W……………………………………… 274.97
• Average power dissipated at the anode, W…………………………………………… 246.079
• Power dissipated at the anode at quiescent current, W…………………………………… 62.5
• Equivalent resistance of the anode circuit of the lamp, Ohm………………………………… 4256

Parameters for the second harmonic

• Peak anode current of the second harmonic, A…………………………………………….0.194
• Oscillatory power of the second harmonic, W………………………………………………………. 219.22
• Equivalent anode resistance for the second harmonic, Ohm …………………………. 11649

Parameters for the third harmonic

• Peak anode current of the third harmonic, A…………………………………………………………… 0.032
• Oscillatory power of the third harmonic, W………………………………………………………. 36.16
• Equivalent anode resistance for the third harmonic, Ohm ………………………… 70625

When determining the basic parameters for two lamps, the selected parameter must be increased or decreased by 2 times based on mathematical logic.

Table 1.

Frequency, MHz	1,85		7,05	10,12	14,15	18,1	21,2	24,9
Cin, pF
L, µH	19,03	9,78	4,99	3,12	1,63		0,73	0,53
Cout, pf	2251	1157
				13,6	19,1	24,6	28,0

The inductor is made of a silver-plated copper tube with a diameter of 6 mm. The design requirement is a high quality factor of the unloaded inductor. The results of calculating the values ​​of the elements of the anode P-circuit of the amplifier for the ranges of 160...12 m (for two lamps) are given in Table 1.

Table 2.

Frequency, MHz		1,85				7,05		10,12		14,15		18,1		21,2		24,9		28,6
L, µH		17,43		8,18		3,39		1,49				0,58		0,32		0,12		0,43
L, µH +20%		20,92		9,82		4,07		1,79		1,44				0,38		0,14		0,52
Frame diameter, mm
Wire diameter, mm
Distance between turns, mm
Number of turns				16,5

The parameters of the output P-circuit of 3 inductors connected in series are given in table. 2. The influence of the metal chassis elements on the inductors was taken to be 20%.

Calculation results of the anode P-circuit of the amplifier for the 10m range (for two lamps)

• Frequency, MHz…………………………………….29.7
• Capacitance of the capacitor Сinp pF ……………………… 30
• Coil inductance, µH……………………….0.43
• Capacitance of the capacitor Couf pF……………………… 352
• Q received………………………………………….19.1

The following initial data were used:

Table 3.

Frequency, MHz	1,85		7,05	10,12	14,15	18,1	21,2	24,9	29,7
Cin, pF	2677	1355
L, µH	3,69	1,89	0,97	0,67	0,48	0,38	0,32	0,27	0,23
Cout, pf	2838	1458

The results of calculating the input matching P-circuits of the amplifier are given in table. 3. The following initial data were used:

Table 4.

Frequency, MHz	1.85		7.05	10.12	14.15	18.1	21.2	24.9	28.6
L, µH	3,69	1,89	0,97	0,67	0,48	0,38	0,32	0,27	0,24
L, µH + 20%	4,43	2,27	1,16		0,58	0,46	0,38	0,32	0,29
Inner diameter L, mm
Wire diameter L, mm
Distance between turns L, mm
Number of turns L		11,9
Q loaded
Efficiency	0,91	0,93	0,94	0,94	0,94	0,94	0,94	0,95	0,95
Overlap, kHz		1200	2350	3373	4717	6033	7067	8300	9533

In table 4 shows the parameters of the inductors of the input P-circuits for each range. The influence of metal parts of the chassis on the inductors was taken to be 20%. Despite the large frequency overlap, especially in the upper ranges, real impedance matching is only possible within one range. When using one filter for two or more ranges, it is necessary to use complex eleptic filters.

Download power amplifier circuits - zip 730kb.

Rice. 17
A KPI with a divided stator can be used as an anode capacitor in the P-circuit and ensures its optimal setting, provided that there is a sufficient distance between the plates (so that the RF voltage does not break through. There is another method for reducing the initial capacitance of the anode KPI. By connecting this capacitor to the tap from the P-circuit coil, we achieve a reduction in the capacitance introduced into the circuit and a decrease in the influence of the KPI on its tuning frequency - UA9LAQ).
Capacitors with air dielectric and vacuum: Capacitors with air dielectric are easier to find, they are cheaper, but they have some of the disadvantages outlined above. Vacuum KPIs are expensive, they are not so easy to find, but only they sometimes provide the P-circuit with everything we want to get from it without the use of additional switchable capacitors of constant capacity. Another advantage of these capacitors is their high operating voltage, insensitivity to pollution of the surrounding atmosphere and changes in its humidity and pressure, and can conduct large RF currents. I have never heard of any vacuum capacitor being shot or arced. An average vacuum-type capacitor used in an HF amplifier can pass through itself RF currents many times greater than those that a real RA is capable of producing. Most vacuum capacitors change the capacitance from minimum to maximum by turning the control axis (multi-turn). The design of the vacuum KPI allows the installation of various reading devices with reset and installation in a specific position required for individual ranges. Limiters at the beginning and end of the KPI capacity adjustment are also provided to avoid its damage. Installing vacuum KPIs may or may not be a problem, since most of these KPIs also contain mounting devices; if they are not provided, they are easy to manufacture. Vacuum control units can be mounted in any position: vertically, horizontally, in a suspended position.
For a truly powerful amplifier, the best choice would be to use vacuum control units, which do not flash even with very high powers supplied to them. Yes, they are not cheap, but the stingy pays twice... (The entry of a small part of air during storage, transportation or operation makes such KPIs absolutely unsuitable due to the occurrence of discharges in them. Before operation, it is necessary to check the KPIs for leaks using a high-voltage tester and protect them from deformation and shock during operation - UA9LAQ).
One moment: The higher the anode voltage used in the amplifier, the more difficult it is to find a suitable KPI with an air dielectric that would withstand a constant anode voltage plus RF and would not cause arcs or problems with capacitance overlap. When the voltage at the anode of the RA lamp(s) is 3 kV, it is still possible to use CPE with an air dielectric; the problems of using them at an anode voltage of 4 kV or more increase exponentially. (The author apparently means the direct connection of the KPI to the anode of the lamp without a separating capacitor, but also, being connected after the separating capacitor, the anode capacitor with an air dielectric in the P-circuit must have an increased distance between the plates: with an increase in the anode voltage, the output resistance increases lamps, which means the RF voltage also increases, which means the risk of breakdown of the gap between the KPI plates increases - UA9LAQ).
When purchasing vacuum control units, pay attention to the condition of the electrodes (plates) inside the glass case. If they have lost their shiny copper appearance, it means that the vacuum in the KPI is most likely broken. If, when the adjusting screw is completely unscrewed, there is no resistance when moving the plates apart, then, most likely, the KPI is broken. In general, the movement of the plates inside the KPI should be accompanied by resistance (force is required), and the insides of the KPI should shine, as if they had just been cleaned. Otherwise, better avoid this KPI!
Range switch: Don't skimp on this important part of RA. Buy yourself the best one you can get. Otherwise, you will simply regret it! Very decent switches are made by Radio Switch Corp. Their Model 86 switch is good, however, the best is the top model 88 switch. This switch is rated at 13 kV and 30 A. Even a 5 kW transmitter will not be able to “arc” this switch. For P- or L- circuits in this switch will require at least two sets of contacts, but three is better. A set of contacts must be provided for each range used. A special adapter must be used to connect the switch axis in the P-circuit to the switch axis of the input circuits ( i.e., when switching PA ranges with one knob). If resistors are used at the PA input (non-adjustable input), then, naturally, there is no need for an adapter. There is also the possibility of using separate switches at the input and output of the amplifier, but to eliminate installation switches to the wrong inappropriate position, it is necessary to apply some kind of interlock: mechanical or electronic.
In Fig. Figure 17 shows the switch configuration, which will help the novice designer understand the requirements for the P-circuit for the ranges of 160...10 meters. Look for similar switches at fairs, markets, and also search on the Internet; you will also find serviceable used ones.
Filament chokes: A choke in the filament circuit of a lamp with a direct filament cathode is absolutely necessary; with heated cathodes, like those of lamps of type 8877, such a choke can be dispensed with. The direct filament cathode can be found in almost all old high-power glass bulb lamps, using thoriated tungsten as the filament and cathode. At such a cathode there is both a large current and a large RF voltage, which must be isolated from penetration into other circuits, so this is where powerful chokes are installed. Such a choke is usually bulky, it is wound with double wire, turn to turn on a ferrite rod and contains a number of turns sufficient to completely remove the RF after the choke. Decoupling capacitors are usually placed immediately after the inductor on the side of the filament voltage supply from the power supply, on the housing. This type of inductor has a very large inductance value, and at the same time, it ensures the passage of large currents through itself. I also tried the use of a toroidal inductor and was pleased with it, especially since this inductor also had small dimensions.
In lamps with heated cathodes, such a cathode is an oxidized “sleeve” dressed on a filament, which heats it to produce electron emission. Cathodes of this type require lower filament currents than the first ones discussed above and do not allow RF propagation, since the cathode “sleeve” has a constant shielding effect (the outer side, in accordance with the skin effect, emits and is drawn into the functioning circuit of RF currents, the lower side is not subject to RF currents and serves as a closed screen, here you can also remember about Foucault currents - UA9LAQ). However, chokes must be included in the filament circuit to prevent even an accidental RF surge from entering the power supply complex. The filament choke in circuits with lamps with heated cathodes should no longer be large, bulky, or have a high inductance, since the RF currents acting in the filament circuit are small. The inductor has small dimensions, is wound with a double wire of sufficient cross-section to pass filament current in rubber or Teflon insulation, winding is carried out on a small ring or rod ferrite core. The inductance of the choke for operation on the ranges of 160...10 meters should be 30...300 µH. Decoupling capacitors are connected from both filament wires to the amplifier body at the point of connection to the inductor on the power supply side. Also place capacitors between the filament wires on the side of the lamp base and the cathode. The HF connection of the filament with the cathode will help equalize the HF potentials on both. This will prevent various kinds of inhomogeneities in the signals: flashes, lumbagoes, crunches, breakdowns on the filament, and will equalize both edges of the filament along the RF, which will eliminate fluctuations in the filament voltage.

Rice. 18
In Fig. Figure 18 shows a typical circuit diagram for switching on a lamp with a heated cathode with a conventional incandescent choke.
ALC: This scheme is a must. You can do without it only if you use a lamp that can be driven by the full power of the available exciter. An example is the 3CX1200A7 lamp, which can swing with a power of up to 120 W, inclusive. However, regardless of whether you use an 8877 or a 3CX800A7, 120 W is enough power to systematically destroy the grids. The ALC system prevents this, but if you "like" changing tubes more often than necessary, don't do any ALC. The best point for connecting the exciter to the amplifier is the point between the input/receive relay and the input tuning device.
The ALC circuit detects a small portion of the exciter RF input signal in the amplifier. This rectified signal is of negative polarity and can vary from -1 to -12 V. The negatively changing signal is fed back to the exciter, which biases the power amplifier in the exciter, which in turn reduces the output power of the exciter and thereby prevents pumping of the final RA.
The procedure for setting the ALC threshold is as follows:
1. Set the amplifier to full output power.
2. Adjust the ALC threshold setting potentiometer to such a level that a barely noticeable decrease in its power appears in the output signal.
3. That's it. Installation is complete.
Once the ALC threshold is set, the RF boost level can be increased or decreased, but the amplifier's maximum output power set using the ALC control will not be exceeded.
The location of the ALC system adjuster can be either on the rear or on the front control panel, but, in any case, is well marked. Installation adjustment pays off in practice, since it cannot be accidentally knocked down (to adjust, you need to take a screwdriver and also crawl under the cover, removing a possible lock). Once set, the ALC threshold adjustment is rarely changed.
In Fig. Figure 19 shows a typical ALC system diagram, simple and effective.

Rice. 19
Adjustments: The most visible part of the amplifier is the control panel, and it is also the most complex. There are many ways to position and control the device. How simple the control panel will be depends on the developer and manufacturer.
There are ready-made boards that can be purchased and installed in an amplifier, but this is a little different, because creating an amplifier yourself from scratch is much more interesting, however, for a beginner it is a way out. Remember, the more complex the device, the more difficult it is to operate and repair. Simplicity and reliability are what you need to start from when developing an amplifier. If a designer wants to create a fully automated amplifier and feels that he can cope with the task, then the flag is in his hands... It will be difficult, and there will be problems, problems... For beginners, I advise you to build the simplest, most reliable amplifiers without any frills. After you build simpler ones, there will be more complex, more elegant devices.
Look at the problem like this: “You are a development engineer, you decided that you will make a device, no matter how much time and effort it requires!”
Afterword: In an age where it's easy to buy and use whatever hobby equipment you want, it's easy to forget the satisfaction that comes from making it yourself. Anyone who buys and then plays with an expensive toy will never experience this feeling. This article is dedicated to those who, after all, want to test it, put their own hands and head to work and make their own RF amplifier, as our colleagues and predecessors did in their time. It is impossible to describe in words that feeling of completion, fulfillment of duty, satisfaction from the experience gained. You’ll also get something new in the process...
If you have any questions, I will be happy to share my knowledge and experience with you if you sincerely wish to do so.
73 de Matt Erickson, KK5DR
Free translation from English: Victor Besedin (UA9LAQ) [email protected]
Tyumen November, 2003

Many shortwave operators are convinced that everything is known about tube amplifiers. And even more... Maybe. But the number of low-quality signals on the air is not decreasing. Quite the opposite. And the saddest thing is that all this is happening against the backdrop of an increase in the number of industrial imported transceivers in use, the transmitter parameters of which are quite high and meet the requirements of the FCC (American Federal Communications Commission). However, some of my colleagues on the air, who have come to terms with the fact that you can’t make the FT 1000 “on the knee” and use RAs designed according to the canons of thirty years ago (GU29 + three GU50s), etc., are still confident that according to RA “we ahead of the rest." Let me note that “they are there, abroad,” not only buying, but also constructing RAs that are worthy of attention and repetition.

As you know, KB power amplifiers use circuits with a common grid (OC) and a common cathode (CC). The output stage with OS is almost a standard for radio amateurs in the CIS. Any lamps are used here - both those specially designed to work in a circuit with OS, and lamps for linear amplification in circuits with OK. Apparently, this can be explained by the following reasons:
- the circuit with OS is theoretically not prone to self-excitation, because the grid is grounded either by HF or galvanically;
- in the circuit with feedback, linearity is 6 dB higher due to negative current feedback;
- RA with OS provide higher energy levels than RA with OK.

Unfortunately, what is good in theory is not always good in practice. When using tetrodes and pentodes with a high slope of the current-voltage characteristic, the third grid or beam-forming plates of which are not connected to the cathode, the RA with OS can self-excite. If installation is unsuccessful, low-quality components (especially capacitors) and poor matching with the transceiver, conditions for phase and amplitude balance are easily created to obtain a classic self-oscillator on HF or VHF using a circuit with OS. In general, matching a transceiver with an RA according to the OS scheme is not as simple as it is sometimes written. Often cited figures, such as 75 ohms for four G811s, are only theoretically correct. The input impedance of the PA with feedback depends on the excitation power, anode current, P-circuit settings, etc. Changing any of these parameters, for example increasing the SWR of the antenna at the edge of the range, causes mismatch at the input of the stage. But that's not all. If a tuned circuit is not used at the input of the PA with OS (and this is a common occurrence in homemade amplifiers), then the excitation voltage becomes asymmetrical, because The current from the exciter flows only during the negative half-cycles of the input voltage, and this increases the level of distortion. Thus, it is possible that the above factors will negate the advantages of the OS scheme. But, nevertheless, RA with OS are popular. Why?

In my opinion, due to excellent energy performance: when it is necessary to “pump up power”, there is no price for a circuit with OS. In this case, the linearity of the amplifier is the last thing people think about, referring to what is firmly understood - “the distortions introduced by the cascade depend little on the choice of the operating point on the characteristic.” For example, a GU74B lamp designed for linear amplification of single-sideband signals in a typical connection in a circuit with OK should have a quiescent current of about 200 mA, and it is unlikely that it will be possible to obtain an output power of more than 750 W (at Ua = 2500 V) without risking the longevity of the lamp, t .To. the power dissipation at the anode will be limiting. It’s another matter if the GU74B is turned on with the OS - the quiescent current can be set to less than 50 mA, and an output power of 1 kW can be obtained. It was not possible to find information about measuring the linearity of such RAs, and arguments like “many QSOs were conducted on this amplifier, and correspondents invariably noted the high quality of the signal” are subjective and therefore unconvincing. Power of more than 1 kW in the above example is provided by the popular industrial ALPHA/POWER ETO 91B, using a pair of GU74B lamps with OK in the operating mode recommended by the manufacturer with known intermodulation characteristics. Apparently, the developers of this amplifier were concerned not only with economic considerations (another lamp increases the cost and complexity of the design), but also with the compliance of the PA parameters with the standards and requirements of the FCC.

The advantage of RA with OS is the absence of the need to stabilize the voltages of the screen and control grids. This is true only for a circuit in which the specified grids are directly connected to a common wire. Such inclusion of modern tetrodes can hardly be considered correct - not only is there no data on the linearity of the cascade in this mode, but also the power dissipation on the grids, as a rule, exceeds the permissible limit. The excitation power for such a circuit is about 100 W, and this causes increased heating of the transceiver, for example, during intensive work on a general call. In addition, with a long connecting cable, it is necessary to use a switched P-circuit at the amplifier input in order to avoid high SWR values ​​and related problems.

The disadvantages of circuits with OK include the need to stabilize the voltages of the screen and control grids; however, in modern tetrodes in AB1 mode, the power consumed by these circuits is small (20...40 W), and the voltage stabilizers on currently available high-voltage transistors are quite simple. If the power transformer does not have the necessary voltages, you can use suitable low-power transformers by connecting them the other way around - with the secondary winding to a filament voltage of 6.3 or 12.6 V. Another disadvantage of the OK circuit is the high power dissipation at the anode during transmission pauses. One of the possible ways to reduce it is shown in Fig. 1 (simplified diagram from).

The excitation voltage is supplied through a capacitive divider to the full-wave rectifier VD1, VD2 and then to the comparator DA1. Triggering of the comparator transfers the lamp from the closed state to the operating mode. During transmission pauses, there is no excitation voltage, the lamp is locked, and the power dissipated at the anode is negligible.

In my opinion, RA with OS can be used on KB with outdated lamps - to reduce the cost of the design, or with lamps specially designed to work in such a connection. The use of a tuned LC circuit of low quality factor or a P-circuit at the input is mandatory. This is especially true for transceivers with wideband transistor output stages, the normal operation of which is possible only with a matched load. Of course, if the output stage of the transceiver has a customizable P-circuit or antenna tuner, and the length of the connecting cable does not exceed 1.5 m (i.e., it represents a capacitance for the frequency range used), such a circuit can be considered as an input for the PA. But in any case, the use of a P-circuit at the RA input significantly reduces the likelihood of self-excitation on VHF. By the way, this is exactly how the vast majority of PAs with OS described in foreign literature and produced by industry for shortwave frequencies are implemented. For radio amateurs who are planning to create an RA with a power of 500 W or more, it is recommended to use lamps specially designed for linear amplification of radio frequency signals in a circuit with OK. This recommendation becomes especially relevant when using expensive “branded” transceivers - in RA with OS, during self-excitation, there is significant power of RF or microwave oscillations at the input, which can lead to failure of either the output stage or the input circuits of the transceiver (depending on switching of the RX - TX circuit at the moment of self-excitation). Alas, this is not the author’s fantasy, but real cases from practice.

And one more problem cannot be ignored when considering tube RAs - with the light hand of V. Zhalnerauskas and V. Drozdov, schemes for constructing the transmitting part of the transceiver have become popular, when, after a bandpass filter, linear amplification of the radio frequency signal by transistor stages without intermediate filtering is used to excite the tube amplifier. Structurally, the transceiver is simplified, but the price of such simplicity is an increased content of spurious emissions if such circuits are not carefully configured.

The situation gets even worse when the output power of the transceiver is not enough to “drive”, for example in the case of the GU74B with OK with a wideband input circuit on a 1:4 transformer. The required gain is usually achieved by an additional broadband stage. If a low IF is used, and after a two- or three-loop DFT, the transmitting path has a gain of 40...60 dB in power, and the P-loop is the only selective circuit of this path, then sufficient suppression of spurious emissions is not ensured. The effects can be heard on the amateur bands every day, such as second harmonics almost equal in power to the main signal. Listen, for example, to the 3680...3860 kHz section, and you will almost certainly hear second harmonic signals from SSB stations on the 160-meter range. The RA itself also has a certain nonlinearity, so even when a spectrally pure radio frequency signal is supplied to it, harmonics are inevitably present at the output. A single P-circuit can be recommended for output power up to 1 kW. At higher power, foreign amateur and industrial PAs use the P-L circuit shown in Fig. 1 - its filtration coefficient is twice as high.

Let us now consider circuit solutions that demonstrate a rather demanding approach to the design of RA.

The publication introduces us to the American version of the homemade RA on the GU74B. George T. Daughters, AB6YL, having decided to remake the Dentron MLA2500 industrial amplifier, originally built on triodes according to the OS circuit, opted for the GU74B lamp (American designation - 4СХ800А). For this project, he considered it optimal to use the mode of supplying the excitation signal to the control grid, where the input power is dissipated by a fifty-ohm resistor between the grid and the common wire. This eliminated the need for customized input circuits and easily provided broadband. The low impedance of the control grid circuit helps avoid self-excitation and provides the transceiver's output stage with a stable resistive load with low SWR. In addition, the very popular commercial amplifier ALPHA/POWER 91B with an output power of 1500 W uses a pair of 4CX800A in this connection - this is an already proven circuit!

The amplifier circuit is shown in Fig. 2.

The large input capacitance of the 4CX800A (about 50 pF) requires the use of inductive compensation, especially in high frequency ranges. Wirewound resistor R1B 6 W/6 Ohm provides the necessary inductance and, together with non-inductive R1A and R1C, complements the load resistance to the required 50 Ohm/50 W. According to AB6YL measurements, at frequencies below 35 MHz the input SWR is less than 1.1.

The energy performance of the amplifier can be improved by connecting a non-inductive resistor R2 with a resistance of up to 30 Ohms between the cathode and the common wire. This resistor provides negative feedback, which reduces the quiescent current and slightly improves linearity; the level of fifth-order components decreases by approximately 3 dB.

The parameters of the P-circuit are not given, because Components from Dentron - MLA2500 were used.

The 4СХ800А filament must be turned on at least 2.5 minutes before the excitation and supply voltages are applied.

Specifications for 4СХ800А/ГУ74Б, supplied to the American market, recommend a bias voltage on the control grid of about -56 V with a screen voltage of +350 V. The control grid power supply consists of a low-power transformer T2, connected in reverse - to the secondary winding, used as the primary, A voltage of 6.3 V is supplied from the main transformer T1, which provides about 60 V AC voltage. At the output of the parametric stabilizer VD9, R12 there is a voltage of -56 V. Any control grid current causes nonlinear distortion leading to splatter. The grid current detector is assembled on an operational amplifier DA1, connected according to a comparator circuit. When the grid current exceeds a few milliamps, the voltage drop across R16 increases, causing the comparator to operate and the red LED to glow.

The screen grid is powered by a voltage stabilizer (VT1, VT2, VD7) with protection against excess current consumption. Relay contacts K2 switch the screen grid between the common wire (via R13) in receive mode and +350 V in transmit mode. Resistor R9 prevents voltage surges when switching the relay. The screen grid current is indicated by the PA1 pointer device, because For tetrodes, the screen grid current is a better indicator of resonance and tuning than the anode current. In transmit mode, the anode quiescent current should be 150...200 mA, while the screen grid current is about -5 mA (if a device without a zero in the middle is used, the arrow will move to the left all the way). The amplifier operates in linear mode and does not need ALC (as long as there is no control grid current) with an anode current of 550...600 mA and a screen grid current of approximately 25 mA. If the screen grid current at resonance exceeds 30 mA, it is necessary to increase the connection to the load or reduce the excitation power. When tuning tetrode amplifiers, it must be remembered that the anode current increases with increasing excitation power; The screen grid current is maximum at resonance or weak connection with the load. When adjusting the amplifier for maximum output power, you should not exceed the parameters specified in the specifications for optimal linearity. The required amplifier excitation power decreases in high frequency ranges. This is explained by the influence of the cathode-heater capacitance, which shunts resistor R2, reducing the environmental impact. This must be kept in mind to avoid over-exciting the amplifier on 15 and 10 meters. (Or use an RF choke in the filament circuit. Ed.)

The amplifier parameters with an input power of about 45 W are given in Table 1. (The output power value seems to be somewhat overestimated. Editor's note.) Before turning off the amplifier after a session, you need to leave it in the standby position for about three minutes - the fan should cool the lamp.

Table 1
Anode voltage 2200 V
Anode quiescent current 170 mA
Maximum anode current 550 mA
Screen grid current maximum 25 mA 0
Power dissipation at the anode without signal 370 W
Power supplied 1200 W
Output power 750W

Part two

The desire to provide reliable and durable performance of a highly linear power amplifier was clearly demonstrated by Mark Mandelkern, KN5S. Schematic diagrams of the amplifier and auxiliary circuits are shown in Fig. 3...8.

Do not be surprised by the abundance of semiconductor devices - their use is justified and deserves attention, especially the use of protection circuits. (However, it cannot be said that all of them are absolutely necessary. Ed.)

When designing the RA, the following goals were pursued:
- power supply of the lamp heater from a stabilized DC source; use of automatic heating and cooling timers;
- measurement of all parameters, including anode current and voltage, without inconvenient switching;
- the presence of stabilized sources of bias and screen voltage, allowing voltage adjustment within a wide range;
- ensuring operability under significant fluctuations in network voltage (this is especially true when working in the field using an electric current generator).

The power source for the heater of powerful generator lamps is rarely given due attention, but it largely determines the longevity of the lamp and the stability of the output power. Warming up of the heater should occur gradually, avoiding current surges through the cold filament. In transmission mode, when intense electron emission occurs, it is very important to ensure a constant filament voltage and, accordingly, a constant cathode temperature. These are the main reasons for using a stabilized power source with a current limiter for incandescent lamps, which eliminates the current surge at the moment of switching on.

The power supply diagram is shown in Fig. 4. The output voltages allow the following adjustment ranges: from 5.5 to 6 V (filament), from 200 to 350 V (screen grid) and from -25 to -125 V (control grid).

The filament voltage stabilizer uses the popular LN723 microcircuit in a typical connection. The significant filament current of the 4CX1000 tetrode (about 9 A) and the connection of the cathode and heater inside the lamp required separate large-section conductors for the high-current circuit (A- and A+); Through the S- and S+ circuit, the output voltage is supplied to the stabilizer comparison circuit. It is best to solder the FU1 10 A fuse rather than use a fuse holder.

The heater control circuit is shown in Fig. 5. The circuit eliminates the use of the amplifier during warm-up and protects the heater from increased voltage if the stabilizer malfunctions. Protection is provided by turning off the heater using relay K2 (Fig. 4). In addition, the air flow sensor through the lamp SA2 (Fig. 4) monitors the performance of the fan. If there is no air flow, this will also cause relay K2 and the filament voltage regulator to turn off.

The warm-up timer (DA3 in Fig. 5) is set to five minutes. According to the specifications, three minutes is enough, but longer heating will extend the life of the lamp. The timer starts only after voltage appears on the heater. This is determined by the comparator DA2.2 connected to point S+. So, for example, if a fuse is blown, the timer will not start until you replace the fuse. When the voltage is exceeded (for example, when the control transistor VT1 breaks down), the trigger on DA2.3 is activated and the transistor VT2 closes, disconnecting the voltage from the winding of relay K2 (point HR in Fig. 5). Capacitor SZ ensures the initial setting of the trigger and, accordingly, the opening of transistor VT2 when the supply voltage is applied.

Along with the warm-up timer, the amplifier needs a timer for the tube to cool down before turning off (DA4). When the amplifier is turned off, the +12 V circuit discharges faster than the +24 V circuit (which has a minimum load in receive mode). A voltage of +24 V appears at the DA2.1 output and the cooling timer starts. After startup, there is a low voltage level at pin 7 of DA4, which triggers relay K1 (Fig. 4), through the contacts of which the operation of the +12/-12 V and +24 V stabilizers is ensured. After approximately three minutes, a high level appears at pin 7, relay K1 returns to its original state, and the amplifier is finally de-energized. The +24 RLY circuit eliminates the operation of the cooling timer if for some reason the amplifier was turned off and immediately turned on. For example, the passage of radio waves ends and the range seems dead - you turn off the amplifier. Suddenly an interesting correspondent appears - the power switch is again in the ON position! When entering transmit mode, the +24RLY voltage forces DA2.1 to a low state and resets the cooling timer.

As in the case of filament voltage, the screen grid voltage stabilizer rarely receives attention when designing a PA. But in vain... Powerful tetrodes, due to the phenomenon of secondary emission, have a negative screen grid current, so the power source of this circuit must not only supply current to the load, but also consume it when the direction changes. Series stabilizer circuits do not provide this, and when a negative screen grid current appears, the series stabilizer transistor may fail. Having lost several high-voltage transistors when setting up the amplifier, radio amateurs come to the decision to install a powerful resistor with a resistance of 5...15 kOhm between the screen grid and the common wire, resigning themselves to useless power dissipation. The use of a parallel voltage stabilizer, which can not only supply, but also receive current, allows for trouble-free operation, but it is advisable to use overcurrent protection.

The screen grid voltage stabilizer is assembled using transistors VT3, VT4 (Fig. 4). Instead of VT3 type 2N2222A, you can use a high-voltage one, excluding the parametric stabilizer R6, VD5, but in this case the stabilization coefficient may deteriorate, because high-voltage transistors have low gain. The output voltage is determined by the sum of the stabilization voltage VD11 and the voltage at the base-emitter junctions of transistors VT3, VT4 (15+0.6+0.6=16.2 V), multiplied by the coefficient determined by the voltage divider R11,R12,R13 (12. ..20) at the output of the stabilizer.

The shunt transistor is mounted directly on an aluminum plate measuring 70x100x5 mm, which, in turn, is mounted on the side wall using ceramic insulators. Resistor R7 limits the peak current through shunt transistor VT4 to about 100 mA.

The RECEPTION-TRANSMIT circuit (Fig. 6) checks six signals: the presence of air flow through the lamp (+12N), the state of the OPERATE-STANDBY switch, the completion of filament heating, the presence of anode voltage, the presence of bias voltage and the state of the overload protection circuit. The reception-transmission switching circuit provides a delay in the operation of the short-circuit relay of 50 ms (Fig. 4) when switching to transmission and a delay in turning off the coaxial relay of 15 ms when switching to reception. If vacuum relays are used, the relay timing can be easily changed for full QSK.

The op-amps of the receive-transmit switching circuit in Fig. 6 use very simple R-C networks to obtain the switching delay. In transmit mode, there is a voltage of about +11 V at the output of DA1.4, which provides a quick charge of capacitor C4 through the diode VD8 of the Kant antenna switching coaxial relay circuit. Capacitor C5 of the screen grid power relay circuit is charged through resistor R26, so the screen relay operates later. When switching to receive mode, a voltage of about -11 V appears at the DA1.4 output, and the reverse process occurs. The KEY input allows you to reduce power dissipation at the anode during transmission pauses and avoid changing the shape of the CW signal sent when working with PA, but for this it is necessary that the transceiver has an appropriate output. The overload blocking circuit (Fig. 7) is triggered when the control or screen grid or anode current exceeds 1 mA, -30 mA and 1150 mA, respectively. The screen grid overload protection circuit operates only at negative currents. The positive current limiter of the screen grid is resistor R27 in the voltage stabilizer circuit. Triggering of the overload protection circuit (Fig. 8) causes the TRANSMISSION circuit to be turned off via the OL circuit (Fig. 6), the additional resistor R2 in the control grid bias circuit is turned on using relay contacts K1, the generator on DA2.4 is turned on and the red LED flashes VD9 OVERLOAD on the front panel.

Only the DA2 microcircuit is powered from a unipolar +24 V source (Fig. 5). All other op amps use +12/-12 V supply voltage.

Figure 7 shows the measurement diagram. Five pointer instruments allow you to measure 10(!) parameters using additional buttons: direct/reflected power in the antenna, control grid current/voltage, anode current/voltage, screen grid current/voltage, filament voltage/current. To read the parameter values ​​indicated through a fraction, you must press the corresponding button. Basic parameters are read immediately; Secondary parameters are of great importance only for the initial setup and for adjustments after replacing the lamp. The simplest non-inverting amplifier used here is to measure the anode voltage (DA2.1). Let us assume that the measurement limit should be 5000 V; The divider R7, R8 (Fig. 3) has a division coefficient of 10,000, i.e. 5000 V at point HV2 is 0.5 V. Resistor R9 does not affect the operation of the circuit since the op-amp has a high input impedance. With a supply voltage of +12/-12 V, the maximum output voltage of the amplifier is about +11/-11 V. Let us assume that +10 V of the output voltage of the operational amplifier corresponds to the full deflection of the meter needle when using a 10 kOhm resistor R22 and a 1 mA device. The required gain (10/0.5) is 20. Having chosen R15 = 10k0m, we find that the feedback resistor should have a resistance of 190 kOhm. The specified resistor is composed of a trimming resistor R20 with a resistance of approximately half the nominal value and a constant resistor R19, selected from a number of standard values.

The anode current measurement circuit is similar. A voltage proportional to the anode current is removed from the negative feedback resistor R2 in the cathode circuit (Fig. 3). Capacitor C2 provides damping of the readings of the measuring device ONCE during SSB operation.

Screen voltage is measured in a similar way. The values ​​of the resistors that determine the gain of the forward and reverse power measurement circuits depend on the design of the directional coupler.

The screen grid current measurement circuit is implemented somewhat differently. It was indicated above that the screen grid current can have both negative and positive values, i.e. a measuring device with a zero in the middle is required. The circuit is implemented on a DA2.3 operational amplifier and has a measurement range of -50...0...50 mA, using a conventional device with a zero on the left for indication.

At 50 mA positive screen grid current, the voltage drop across resistor R23 (Fig. 4) is -5V at point -E2. Thus, a gain of -1 is required from the op amp to produce the required +5V output voltage to deflect the needle by half scale. When R23=10 kOhm, the feedback resistor should have a nominal value of 10 kOhm; tuning resistors R32 and constant resistors R30 are used. To shift the instrument needle to the middle of the scale at a supply voltage of -12 V, a gain of +5/-12=-0.417 is required. The exact value of the gain and, accordingly, the zero of the scale is set by trimming resistor R25.

Operational amplifiers DA2.2, DA2.4 have an extended filament voltage measurement scale. The differential amplifier DA2.2 converts the filament voltage to unipolar, because point S is not directly connected to the common wire. The DA2.4 summing amplifier implements an extended measurement scale - from 5.0 to 6.0 V. In fact, it is a voltmeter with a measurement limit of 1 V, biased to the initial value of 5 V.

In rectifier circuits, the diodes used must be designed for the appropriate current, the rest - any pulsed silicon diodes. With the exception of high-voltage transistors, any low-power corresponding structure can be used. Operational amplifiers - LM324 or similar. Measuring instruments - PA1...PA5 with a total deviation current of 1 mA.

The above schemes certainly complicate RA. But for reliable everyday work on air and in competitions, it’s worth spending extra effort on creating a truly high-quality device. If there are more clean and loud signals on the bands, then all radio amateurs will benefit. For QRO without QRM! I express my gratitude to I. Goncharenko (EU1TT), whose advice and comments were of great help when working on the article.

Literature

1. Bunimovich S., Yailenko L. Amateur single-sideband radio communication technology. - Moscow, DOSAAF, 1970.
2. Radio, 1986, N4, P.20.
3. Drozdov V. Amateur KB transceivers. - Moscow, Radio and Communications, 1988.
4. QST ON CD-ROM, 1996, N5.
5. http: //www.svetlana.com/.
6. QEX ON CD-ROM, 1996, N5.
7. QEX ON CD-ROM, 1996, N11.
8. Radio amateur. KB and UKV, 1998, N2, P.24.
9. Radio Amateur, 1992, N6, P.38.
10. ALPHA/POWER ETO 91B User's Manual.

G.LIVER (EW1EA) "HF and VHF" No. 9 1998

tube, transistor

As practice shows, few radio amateurs work QRP, while most sooner or later begin to dream of increasing the transmitter power. That's when and the question arises about preference to a lamp or a transistor. Long-term practice of operating both of them has shown that tube amplifiers are much simpler to manufacture and less critical to operating conditions, and the weight of the anode transformers is practically compensated by the weight of the radiators necessary for cooling powerful transistors, which are more capricious in operation, especially to overloads, so experiments with they are quite expensive. It is easier to make a power supply with a power of 2 kW at 2000 V at a current of 1 A than 20 V at a current of 100 A. The presence of small-sized electrolytic capacitors designed for high voltage and large capacity allows you to create small-sized high-voltage sources for tube amplifiers directly from the network without using power transformers.

The power amplifier is one of the main attributes of a contestant's and DX-man's radio station. Depends on his choice results in competitions and ratings.

HF power amplifiers on tubes, transistor HF power amplifiers

An output amplifier (power amplifier - PA) is an amplifier loaded onto an antenna. The output amplifier consumes most of the power. The operation of the PA mainly determines the energy performance of the entire radio station, so the main requirement for the output stage is to obtain high energy performance. In addition, good filtering of higher harmonics is very important for the output amplifier.

A good modern HF power amplifier is a rather complex and labor-intensive device, as evidenced by world prices for branded PAs, at least in relation to the cost of middle-class transceivers produced by the same companies. This is explained, firstly, by the high cost of the lamps themselves used in the PA, and secondly, also by the high percentage of manual labor in their manufacture.

ACOM-1000

The ACOM 1000 HF power amplifier is one of the most worthy HF power amplifiers in the world. The output power of ACOM 1000 is at least 1000 W on all amateur radio bands from 160 to 6 meters.

Without antenna tuner

The amplifier functions as an antenna tuner with an SWR of up to 3:1, thus allowing you to change antennas faster and use them over a larger frequency band, saving tuning time.

One output tube 4CX800A (GU-74B)

The amplifier uses a high-performance metal-ceramic tetrode produced by the Svetlana plant with an anode dissipation power of 800 W (with forced air cooling and grid control).

Technical characteristics of the ACOM 1000 power amplifier:

• Frequency range: all amateur radio bands from 1.8 to 54 MHz; extensions and/or changes upon request.
• Output power: 1000 W peak (PEP) or push mode, no operating mode restrictions.
• Intermodulation distortion: better than 35 dB below peak rated power.
• Hum and Noise: Better than 40 dB below peak rated power.

Harmonic Suppression:

• 1.8 - 29.7 MHz - better than 50 dB below peak rated power.
• 50 – 54 MHz - better than 66 dB below peak rated power.

Input and output impedance:

• nominal: 50 ohms, unbalanced, UHF connectors (SO239);
• input circuit: wideband, SWR less than 1.3:1 in a continuous frequency band of 1.8-54 MHz (no need for tuning and switching);
• pass-through SWR less than 1.1:1 in the continuous frequency band 1.8-54 MHz;
• Output matching capabilities: better than 3:1 SWR or greater at reduced power levels.

• RF gain: 12.5 dB typical, frequency response less than 1 dB (with 50 - 60 W input signal at rated output power).
• Supply voltage: 170-264 V (200, 210, 220, 230 and 240 V taps, 100, 110 and 120 V taps on request, with tolerance +10% - 15%), 50-60 Hz, single phase, Consumption 2000 VA at full power.
• Meets the safety requirements of EEC countries and the requirements for electromagnetic compatibility parameters, as well as the rules of the US Federal Communications Commission (FCC) (the unit is installed on the 6, 10 and 12 m bands).
• Dimensions and weight (in working condition): 422x355x182 mm, 22 kg
• Requirements for environmental parameters during operation:
• temperature range: 0...+50°С;
• relative air humidity: up to 75% at a temperature of +35°C;
• altitude: up to 3000 m above sea level, without deterioration of technical parameters.

ACOM-1011

The ACOM 1011 power amplifier is developed on the basis of the well-known ACOM 1010.

The outstanding performance characteristics of the latter have been noted by many radio amateurs around the world.

At the WRTC Championship in Brazil, teams used the ACOM 1010 amplifier and it was recognized as the most optimal for both stationary use and DXpeditions.

The main differences between the two amplifiers:

• The ACOM 1011 uses two 4CX250B tubes, currently produced by many of the most renowned tube manufacturers, and provides the same power output as a single GU-74B tube.
• The lamp warm-up time has been reduced to 30 seconds.
• The tube panels are custom made by ACOM and designed specifically for installation in this amplifier.
• The ACOM 1011 uses a new fan designed and manufactured specifically for ACOM based on the well-known and proven fans used in the ACOM 1000 and ACOM 2000 models. It uses similar components, which provides better cooling and quieter operation of the amplifier overall compared to with ACOM 1010.
• ACOM 1011 has some differences both outside and inside. The more durable metal construction improves its performance during transport and DXpedition work.

ACOM-2000

Automatic power amplifier ACOM 2000A is an HF amplifier with the most advanced technical characteristics in the world of amplifiers manufactured for amateur radio applications. The ACOM 2000A is the first amateur radio power amplifier to combine a fully automated setup process with sophisticated digital control capabilities. The new amplifier has an improved design and produces maximum permitted power in all radiation modes and operates on all amateur radio HF bands.

Cutting-edge technology improves classic amplifier design

Fully automatic setup

The automatic tuning functions of the ACOM 2000A amplifier are a real breakthrough in the field of HF power amplifier design. There is no need to think about using an antenna tuner with an SWR of up to 3:1 (2:1 in the 160 meter range). The process of matching the actual characteristic impedance with the optimal lamp load is fully automated. This process lasts no more than one second and does not require much experience.

QSK – full duplex mode

Full duplex operation (QSK) is based on a built-in vacuum relay. The sequence of switching from transmitting to receiving mode is provided by a dedicated microprocessor.

Remote control

Only the remote control should be located near the operator. The amplifier itself can be placed up to 3 m (10 ft) away. GLE functions include: amplifier status on the LCD display, control of all functions, measurement and/or monitoring of the twenty most important parameters of the amplifier, operational technical information, troubleshooting suggestions, recording of the number of operating hours, password protection.

Protection

• Continuous monitoring and protection of such parameters and functions as:
• all lamp voltages and currents,
• supply voltages,
• overheat,
• pumping based on input signal,
• insufficient amount of cooling air,
• internal and external RF sparking (in amplifier, antenna switch, tuner or antennas),
• sequence of switching from transmit to receive T/R,
• switching the antenna relay during transmission,
• quality of matching with the antenna,
• reflected power level,
• saved data,
• inrush current of the supply voltage network,
• Lid lock for operator safety.

Technical characteristics of the ACOM 2000A power amplifier:

• Output power: 1500-2000 W in push mode or SSB mode - no time limit. Continuous radiation mode - 1500 W output power - no time limit when using an additional cooling fan.
• Frequency range: all amateur radio bands from 1.8 to 24.5 MHz. 28 MHz band only with modifications for licensed radio amateurs.
• Reranging/Tuning: Initial output matching occurs in less than 3 seconds (typically 0.5 seconds). The process of adjusting to previously agreed upon settings/band switching takes less than 0.2 seconds to move to another part of the same range, and less than 1 second when moving to another range.
• Non-volatile storage device (memory) for configuring up to 10 antennas per frequency segment.
• Drive signal power: typically 50 Watts with 1500 Watts output power.
• Input impedance: nominal 50 Ohm. SWR<1.5:1.
• Output tolerance: up to 3:1 VSWR (2:1 at 160 meters) at full output power before high VSWR protection circuit is activated. Higher SWR values ​​are matched at lower output power.
• Harmonic Content: At least 50 dB below peak at 1500 Watts.
• Intermodulation Interference: At least 35 dB below peak at 1500 Watts.
• T/R Switching and Keying: Vacuum Relay: Capable of Full Duplex (QSK) operation.
• Output tubes and circuits: tetrodes 4CX800A/GU74B (2 pcs.), resistive grid, PI-L output circuit with negative RF feedback. Adjustable screen grid voltage.
• Automatic Level Control (ALC): Negative grid voltage control, -11V maximum, rear panel adjustable.
• The remote control unit provides monitoring of all operating parameters of the amplifier.
• Protection: limiting the current of the control and screen grid, due to power surges (the possibility of smooth switching is provided), shutdown when the reflected power value is exceeded, when sparking in the RF circuit, access is password protected if necessary, correction of alternating switching between transmit and receive modes (T/R) , removal of lamp cooling air, blocking and grounding device for the high voltage circuit when opening the cover.
• Fault diagnosis: remote control display, plus indicators, plus information device "INFO Box" for the last 12 events. Computer interface (RS-232), plus remote telephone polling line function.
• Cooling: Full forced airflow inside the case. Rubber insulated fan.
• Transformer: 3.5 KVA with Unisil-Ha strip core.
• Power supply requirements: 100/120/200/220/240 Volts AC. 50-60 Hertz. 3500 VA, single phase, at full power.
• Overall dimensions: HF unit: length 440 mm, height 180 mm, depth 450 mm, remote control unit: length 135 mm, height 25 mm, depth 170 mm
• Transported in two cardboard boxes, total weight 36 kg.
• There are no controls on the HF unit, with the exception of the ON/OFF switch.

Alpha-9500

The Alpha-9500 is no ordinary linear amplifier, but the culmination of over 40 years of design and engineering.

Alpha-9500 is an advanced technology, auto-tuning linear amplifier easily provides 1500W of output power with a minimum input power of only 45W.

SPECIFICATIONS:

All amateur bands from 1.8 - 29.7 MHz

• Output power: 1500 W minimum, on all bands and types of radiation
• 3rd order IM:< -30 дБн
• SWR allowed: 3:1
• Power input: 45-60 W to achieve rated full power
• Lamp: one 3CX1500/8877 - high power and performance triode with a dissipation power of 1500 W provides the declared power in all frequency ranges, in all modes, in all duty cycles.
• Cooling: Forced air from two fans
• Antenna Outputs: Comes standard with 4 SO-239 connectors, but can be changed to N type on the rear panel by removing 4 screws.
• Antenna selection: internal antenna 4-port switch with 1 or 2 outputs per band
• Calibrated Wattmeter: The Bruene Wattmeter allows you to simultaneously measure forward and reverse power and display this information in an easy-to-read front panel bar graph. It also uses the information to simultaneously control the amplifier's gains.
• Protection mechanisms: high-voltage blocking and power supply blocking.
• Bypass Mode: There are two "ON" power switches on the front panel of the ALPHA-9500.
• "ON1" activates the Wattmeter and antenna switch without turning off the power to the amplifier itself, and sets the amplifier to bypass mode.
• The amplifier itself is turned on with the "ON2" button.
• Input: Comes standard with SO-239 BIRD connector, but can be changed to BIRD N type
• Tuning/switching ranges: Automatic, plus manual control
• Power: 100, 120, 200, 220, 240 VAC, 50/60 Hz, automatic selection. At 240 VAC, the amplifier draws up to 20 amps.
• Interface: serial port and USB. Full remote control function.
• Protection: Protection against all common faults.
• Display: The display shows histograms of power, SWR, grid current, plate current, plate voltage and gain - all at once. The digital instrument panel can display input power, plate current, plate voltage, grid current, SWR, filament voltage and PEP output.
• Tx/Rx switching: two Gigavac proprietary vacuum relays allow QSK to QRO operation.
• Output power: 1500 W.
• Weight: 95 lbs
• Dimensions: 17.5"W X 7.5"H X 19.75"D

Ameritron AL-1500

Ameritron AL-1500 is one of the most powerful linear amplifiers, covering all HF and WARC ranges.

It uses a manually tuned amplifier, which is designed around a single 3CX1500/8877 ceramic tube and has an efficiency of at least 62-65%.

With an input power of 65 W, it produces the legal maximum power with a large margin, up to 2500 watts.

The amplifier features a Hypersil ® transformer, dual backlit instruments, adjustable ALC, delay time adjustment, current protection and more.

Price (approximately in the Russian Federation) = $3650

Ameritron AL-572X

The Ameritron AL-572 amplifier is made using four 572B tubes using a common grid design. The Ameritron AL-572 amplifier uses tube capacitance neutralization, which improves performance and stability in the HF ranges. The lamps are installed vertically, which significantly reduces the risk of interelectrode short circuits

To match the input of the Ameritron AL-572 amplifier with the output of the transmitter, separate P-circuits are installed at the input for each of the operating ranges. The use of a tuned input equalizes the load on the output stage of the transceiver and allows you to get an SWR close to 1 on all bands. Additional adjustment of the circuits is possible through the holes in the rear panel of the amplifier.

The anode power supply is assembled using a voltage doubling transformer circuit and uses high-capacity electrolytic capacitors. The anode transformer is wound on a prefabricated steel core made of plates coated with high temperature resistant silicone coating, providing high power density with low weight. The anode no-load voltage is 2900 volts, at full load about 2500 volts. To reduce the temperature inside the Ameritron AL-572 case, a low-speed computer-type fan is used to circulate air at a low noise level.

Details of the Ameritron AL-572 output circuit (frameless coils made of thick wire, anode capacitor with ceramic insulators and a large gap between the plates, range switch on a ceramic dielectric) ensure reliable operation and high efficiency of the oscillatory system. The handles of variable capacitors are equipped with verniers with retardation and rotor position indication.

The Ameritron AL-572 amplifier also has an ALC system, a switch for operating and bypass modes, an indication of transmission operation and instruments for measuring the voltage of the anode power source / anode current and the value of the grid current. Both measuring instruments are backlit. For QSK operation, it is possible to install an additional QSK-5 module.

Price (approximately in the Russian Federation) = $2240

Specifications

• Peak output power: SSB 1300 Watts, CW 1000 Watts
• Excitation power from the transceiver 50-70 Watts
• Lamps: 4 572B lamps with neutralization in inclusion with a common grid
• Power supply: mains 220 volts
• Dimensions: 210x370x394 mm
• Weight: 18 kg
• Manufacture: USA

Ameritron AL-800X

Tube power amplifier for HF transceivers

Operating frequency range: from 1 to 30 MHz

Output power: 1250 Watts (peak)

Built on a 3CX800A7 tube

Price (approximately in the Russian Federation) = $2900

Ameritron AL-80BX

The Ameritron AL-80B linear power amplifier is made using a 3-500Z tube using a common grid design. The lamp is installed vertically, which significantly reduces the risk of interelectrode short circuits.

To match the input of the Ameritron AL-80B amplifier with the output of the transmitter, separate P-circuits are installed at the input for each of the operating ranges. The use of a tuned input equalizes the load on the output stage of the transceiver and allows you to get an SWR close to 1 on all bands. Additional adjustment of the circuits is possible through the holes in the rear panel of the amplifier.

The anode power supply of the Ameritron AL-80B amplifier is assembled using a transformer circuit with voltage doubling and uses high-capacity electrolytic capacitors. The anode transformer is wound on a prefabricated steel core made of plates coated with high temperature resistant silicone coating, providing high power density with low weight. The anode no-load voltage is 3100 volts, at full load about 2700 volts. To reduce the temperature inside the case, a low-speed computer-type fan is used, which ensures air circulation at a low noise level.

The details of the output circuit of the Ameritron AL-80B amplifier (frameless coils made of thick wire, an anode capacitor with ceramic insulators and a large gap between the plates, a range switch on a ceramic dielectric) ensure reliable operation and high efficiency of the oscillatory system. The handles of variable capacitors are equipped with verniers with retardation and rotor position indication.

The Ameritron AL-80B amplifier also has an ALC system, a switch for operating and bypass modes, an indication of transmission operation and instruments for measuring the voltage of the anode power supply/anode current and the magnitude of the grid current. For QSK operation, it is possible to install an additional QSK-5 module.

Price (approximately in the Russian Federation) = $1990

Specifications

• Operating ranges: 10-160 meters, including WARC
• Peak output power: SSB 1000 Watts, CW 800 Watts
• Excitation power from the transceiver 85-100 Watts
• Lamps: 3-500Z lamp with neutralization in inclusion with a common grid
• Input and output impedance: 50 ohms
• Power supply: mains 220 volts
• Dimensions: 210x370x394 mm
• Weight: 22 kg
• Manufacture: USA

Ameritron AL-811

The Ameritron AL-811 HX linear power amplifier is made using four 811A lamps (a complete analogue is the G-811 lamp) according to a circuit with a common grid. The lamps are installed vertically, which significantly reduces the risk of interelectrode short circuits.

To match the amplifier input with the transmitter output, separate P-circuits are installed at the input for each of the operating ranges. The use of a tuned input equalizes the load on the output stage of the transceiver and allows you to get an SWR close to 1 on all bands. Additional adjustment of the circuits is possible through the holes in the rear panel of the amplifier.

The anode power source is assembled using a transformer bridge circuit and uses high-capacity electrolytic capacitors. The anode transformer is wound on a prefabricated steel core made of plates with a high-temperature resistant silicone coating, providing high power density with low weight (8 kg). The anode no-load voltage is 1700 volts, at full load about 1500 volts. To reduce the temperature inside the case, a low-speed computer-type fan is used, providing air circulation at a low noise level.

The amplifier also has an ALC system, a switch for operating and bypass modes, an indication of transmission operation and instruments for measuring the voltage of the anode power source/anode current and the value of the grid current. For QSK operation, it is possible to install an additional QSK-5 module.

Price (approximately in the Russian Federation) = $1200

Specifications

• Peak output power - in SSB mode 800 Watt, in CW mode 600 Watt (excitation power from the transceiver 50-70 Watt)
• Input and output impedance - 50 Ohm
• Operating ranges - 10-160 meters, including WARC
• 4 811A lamps included with a common grid
• Adjustable ALC output
• Supply voltage 240 volts, commutable
• taps for mains power 100/110/120/210/220/230 volts
• Weight 15 kg

Ameritron AL-82X

The Ameritron AL-82X linear power amplifier is made using two 3-500Z tubes using a common grid design. The Ameritron AL-82 amplifier uses tube capacitance neutralization, which improves performance and stability in the HF ranges. The tubes in the Ameritron AL-82 amplifier are mounted vertically, which significantly reduces the risk of interelectrode short circuits.

To match the input of the Ameritron AL-82X amplifier with the output of the transmitter, separate P-circuits are installed at the input for each of the operating ranges. The use of a tuned input of the Ameritron AL-82 amplifier equalizes the load on the output stage of the transceiver and allows you to get an SWR close to 1 on all bands. Additional adjustment of the circuits is possible through the holes in the rear panel of the amplifier.

The anode power supply of the Ameritron AL-82 amplifier is assembled using a voltage-doubling transformer circuit and uses high-capacity electrolytic capacitors. The anode transformer is wound on a prefabricated steel core made of plates coated with high temperature resistant silicone coating, providing high power density with low weight. The anode no-load voltage is 3800 volts, at full load about 3300 volts. To reduce the temperature inside the Ameritron AL-82 amplifier, a low-speed computer-type fan is used to circulate air at a low noise level.

Details of the output circuit (frameless coils made of thick wire, an anode capacitor with ceramic insulators and a large gap between the plates, a range switch on a ceramic dielectric) ensure reliable operation and high efficiency of the oscillatory system. The handles of variable capacitors are equipped with verniers with retardation and rotor position indication.

The Ameritron AL-82X amplifier also has an ALC system, a switch for operating and bypass modes, an indication of transmission operation and instruments for measuring the voltage of the anode power source/anode current and the value of the grid current. Both measuring instruments are backlit. For QSK operation, it is possible to install an additional QSK-5 module.

Price (approximately in the Russian Federation) = $3000

Ameritron AL-82X Amplifier Specifications

• Operating ranges 10-160 meters, including WARC
• Peak output power: SSB 1800 Watts, CW 1500 Watts
• Excitation power from the transceiver 100 Watt
• Lamps: 2 lamps 3-500Z lamps with neutralization in inclusion with a common grid
• Input and output impedance 50 Ohm
• Power supply 220 volts
• Dimensions 250x432x470 mm
• Weight 35 kg
• Made in USA

Ameritron ALS-1300

Ameritron offers its new solid-state amplifier ALS-1300.

The amplifier output power is 1200W in the frequency range 1.5 - 22 MHz.

The amplifier does not require time to rebuild; 8 pcs MRF-150 FETs are used as output transistors.

The amplifier uses a fan whose rotation speed is controlled by temperature sensors to ensure minimal noise.

The ALS-500RC remote control can be used with the ALS-1300 amplifier

Ameritron ALS-500M

The amplifier uses four powerful 2SC2879 bipolar transistors

The amplifier is made without the use of vacuum tubes, so it does not require preheating

The amplifier does not need to be adjusted. Switching ranges from 1.5 to 29 MHz is carried out with one knob

The amplifier monitors the load resistance and if it deviates more than the permissible norm, “bypass” is activated

The amplifier has a built-in current consumption indicator that allows you to monitor the collector current of the output transistors

To bypass the amplifier, you do not need to disconnect it. You just need to switch it to the “off” position

The weight of the amplifier is only 3.9 kg with dimensions of 360x90x230 mm

When operating the amplifier in stationary mode, it is recommended to use a power source with an output voltage of 13.8 V and an operating current of at least 80 A.

Price (approximately in the Russian Federation) = $1050

Technical characteristics of the ASL-500M power amplifier:

• Frequency range: 1.5 - 30 MHz
• Output power: 500 W peak (PEP) or 400 W in CW mode
• Drive signal power: typically 60-70 W
• Supply voltage: 13.8 V, consumption 80 A
• Harmonic Rejection: 1.8 – 8 MHz – better than 60 dB below peak rated power, 9 – 30 MHz – better than 70 dB below peak rated power
• When operating the amplifier in stationary mode, it is recommended to use a power source with a maximum output current of at least 80A.

Ameritron ALS-600

No setup, no fuss, no worry - just plug and play

Includes 600 W output power, continuous frequency range 1.5-22 MHz, instantaneous band switching, no warm-up time, no child-hazardous lamps, maximum SWR protection, completely silent, very compact.

The revolutionary AMERITRON ALS-600 amplifier is the only linear amplifier in ham radio that uses four reliable RF power TMOS FETs - delivering unsurpassed solid-state quality and requiring no tuning. Price includes non-tuned FET amplifier and 120/220 VAC, 50/60 Hz power supply for home use.

You get instant range switching, no setup required, no warm-up time, no fuss! The ALS-600 amplifier provides a maximum 600 W envelope output power and 500 W CW power over a continuous frequency range of 1.5 to 22 MHz

The ALS-600 amplifier is completely silent. The low-speed, low-volume fan is so silent that it is difficult to detect its presence, unlike the noisy blowers found in other amplifiers. The ALS-600 amplifier has small dimensions: 152x241x305 mm - it takes up less space than your radio! Weighs only 5.7 kg.

The two-pointer SWR and power meter with backlight allows you to read the values ​​of SWR, maximum power of the incident and reflected waves simultaneously. The Operate/Standby switch allows you to operate in low power mode, but you can instantly switch to full power mode if needed.

You get the ability to control the ALC system from the front panel! This unique AMERITRON system allows you to adjust the power output on a convenient front panel indicator. Additionally, you get LED indicators for transmit, ALC and SWR on the front panel. The 12 VDC output jack allows you to power low-current accessories. Enjoy 600 watts of non-tuning solid state amplifier power. A pair of RJ45 remote control interface jacks on this amplifier allow you to control the ALS-600 amplifier either manually using the ALS-500RC compact remote control unit, or automatically using the ARI-500 automatic band selector. The Automatic Band Switch reads band data from your transceiver and automatically changes the ALS-600 amplifier's bands when the bands on the transceiver change.

Price (approximately in the Russian Federation) = $1780

Expert 1K-FA

Fully automatic 1KW transistor linear amplifier.

Built-in power supply and automatic antenna tuner. Dimensions: 28x32x14 cm (including connection connectors).

Weight about 20 kg.

The Expert 1K-FA amplifier uses two processors, one of which is designed to automatically adjust the output P-circuit. (System S.A.T.s) More than 13,000 software elements provide a unique set of technical characteristics not found in other models.

Possibility of easy connection to all models of Icom, Yaesu, Kenwood transceivers, automatic antenna tuner, control of antenna characteristics, immediate broadcasting. Similar results when working with models from other companies and homemade equipment. The operator's functions are limited to rotating the frequency control knob in the transceiver.

From 1.8 MHz to 50 MHz including WARC bands. Fully transistor design. 1 kW PEP in SSB mode (nameplate value). 900 W in CW mode (rated value) 700 W PEP in the 50 MHz band (rated value).

Automatic selection of full/half power by operator command in CW and SSB modes, for digital types of operation and providing automatic amplifier protection. Does not require time to warm up.

The amplification elements are not subject to aging (CMOS transistors are used). Built-in automatic antenna tuner. It is possible to match antennas up to SWR values ​​of 3:1 on HF, and 2.5:1 on 6 meters. Switching up to 4 antennas (SO239 connectors). Switching bands, antennas and all adjustments are carried out in 10 milliseconds. When working only from the transceiver, adjustments, switching of bands and antennas are carried out in the “standby” mode. Availability of two entrances. SO 239 connectors are used.

Drive power 20 W.

Continuous monitoring of temperature, overcurrent and voltage, SWR level, reflected power level, maximum RF tuner voltage, input power “pumping”, imbalance of amplifier stages. Full duplex mode (QSK). Low noise operation. The amplifier and transceiver can be turned on and off independently. The large LCD display displays a large amount of information.

Connection via RS 232 port for control via PC. For ease of carrying, the amplifier fits into a small bag. Possible to work on field days and DX expeditions.

BLA 1000

RM BLA-1000 is a new transistor amplifier, with an output power of up to 1000W, which implements all the most advanced achievements in amplifier design. The output stage of the amplifier is made of two super-power field-effect (MOSFET) transistors MRF-157. A 2-cycle bridge amplification circuit (Push-Pull type), operating in AB2 mode, provides high gain and good amplifier efficiency while maintaining high linearity.

For the convenience of covering all operating ranges, there are 2 antenna ports on the rear panel of the amplifier. For example, you can connect high-frequency range antennas to one port, and low-frequency range antennas to the second.

To control the linearity of the amplifier, there is an ALC input on the rear panel. The possibility of both automatic control of the ALC level and from the transceiver has been implemented. ALC parameters can be adjusted manually using 2 resistors. The release time of the transmit relay (RX-delay) can be adjusted in the range of 0...2.5 seconds in steps of 10 ms.

Switching the “Receive/Transmit” mode can be done either from the transceiver or automatically (Int. VOX). For this purpose, there is an RC connector - “PTT” on the rear panel of the amplifier.

The amplifier is powered by its built-in switching power supply. The amplifier's high output power is obtained by feeding the transistors with high voltage - 48 Volts. In this case, the current consumption at the signal peak can reach 50 Amperes.

One of the interesting features of this amplifier is its ability to operate in fully automatic mode. In this mode, you do not need to switch not only the “Receive/Transmit” mode, but also the operating range of the amplifier. The frequency meter built into the microprocessor will automatically determine the transmission frequency and select the desired low-pass filter. This function will be especially useful for using the amplifier in “unattended areas” or “enclosed spaces” of industrial radio communication structures.

Price (approximately in the Russian Federation) = $4590

Technical characteristics of the power amplifier RM BLA-1000

• Frequency range 1.5-30 and 48-55 MHz
• Supply voltage 220-240 Volts; 15.5 A
• Input power 10-100 Watt
• Output power 1000 Watt
• Impedance Input/Output 50 Ohm
• Overall dimensions 495 x 230 x 462 mm
• Weight 30 kg

BLA 350

New, inexpensive amplifier RM BLA-350. An ideal solution for a beginner or intermediate radio amateur who has decided to amplify the signal of his transceiver or protect the output stage for little money. Due to the built-in powerful power supply, the amplifier takes up little space on the table.

The output stage of the amplifier is made of two powerful field-effect (MOSFET) transistors SD2941. A 2-cycle bridge amplification circuit (Push-Pull type), operating in AB2 mode, provides high gain and good amplifier efficiency while maintaining high linearity. Additional purity of the output signal is provided by 7 low-pass filters of the 7th order, which is an important parameter for basic amplifiers.

Thanks to microprocessor control, the control of the amplifier operating modes is fully automated and temperature, SWR and input power control is implemented. Flexible configuration of protection and alarm parameters is possible when threshold values ​​are exceeded.

Switching of the “Reception/Transmission” mode can be controlled either from the transceiver or automatically (Int. VOX). For this purpose, there is an RC connector - “PTT” on the rear panel of the amplifier.

One of the interesting features of this amplifier is its ability to operate in fully automatic mode. In this mode, you do not need to switch not only the “Reception/Transmission” mode, but also the operating range of the amplifier. The frequency meter built into the microprocessor will automatically determine the transmission frequency and select the desired low-pass filter. This function will be especially useful for using the amplifier in “unattended areas” or “enclosed spaces” of industrial radio communication structures.

Price (approximately in the Russian Federation) = $1090

Technical characteristics of the power amplifier RM BLA-350

• Frequency range 1.5-30 MHz (Including WARC bands)
• Modulation types AM/FM/SSB/CW/DIGI
• Supply voltage 220-240 Volts; 8 A
• Input power 1-10 Watt
• Output power 350 Watt
• Impedance Input/Output 50 Ohm
• Overall dimensions 155 x 355 x 270 mm
• Weight 13 kg

Elecraft KPA-500

The power amplifier is designed to operate on all amateur radio HF bands from 160 to 6 meters (including WARC bands) in all operating modes. The KPA-500 automatically tunes to your transceiver's frequency.

An all-solid-state amplifier with a power of 500 W on powerful FET transistors, has the same dimensions as the Elecraft K3 transceiver and fits perfectly into the line of devices of this company.

The amplifier has an alphanumeric display, a bright LED indicator and a reliable, powerful built-in power supply. The device works with any transceiver that uses a grounded PTT output. When pumping or increasing the SWR, the power is automatically reduced by 2.5 dB, and when the problem is eliminated, it returns to the nominal value.

The amplifier provides ultra-fast, silent QSK using a high-power PIN diode switch. The device has a six-speed temperature-controlled fan. When using the optional KPAK3AUX cable, enhanced integration with the K3 transceiver is provided:

• manual control buttons on the KRA500 panel control the ranges and drive level on the K3;
• data on switching ranges is transmitted from K3 before the start of transmission;
• PTT is transmitted via cable, no separate control is required;
• K3 detects the current state of the amplifier and adjusts the drive level according to one of two memory states on each band.

When the Internet is connected, the presence of new firmware versions is automatically detected from the company server via the RS232 port.

HLA-150

Price (approximately in the Russian Federation) = $520

• Input power: 1 - 8 W.
• Output Power: 150W CW or 200W PEP in SSB.
• Supply voltage: 13.8 V.
• Maximum current consumption: up to 24 A.
• Dimensions: 170x225x62 mm, weight 1.8 kg.

HLA-300

The amplifier has microprocessor control, a frequency range of 1.5-30 MHz, LED indicators of output power and operating range, automatic TX/RX switching. Band switching can be done automatically or manually. The amplifier has band filters on the output that are switched manually when the range changes.

In the event of a malfunction of the amplifier or antenna-feeder system, or an increase in the level of spurious emissions, the protection system will automatically turn off the amplifier and/or connect the transceiver directly to the antenna (“bypass” mode). To manually enable the bypass mode, simply turn off the power to the amplifier.

Input power 5 - 15 W.

Output power 300 W CW or 400 W PEP in SSB.

Supply voltage 13.8 V.

Maximum current consumption up to 45 A.

Dimensions 450x190x80 mm, weight 3 kg. Price (approximately in the Russian Federation) = $750

OM Power OM 1500

Linear power amplifier for operation on all amateur bands from 1.8 to 29 MHz (including WARC bands) + 50 MHz with all types of modulation. Equipped with a ceramic tetrode GS-23B.

Specifications:

Operating frequency range: amateur bands from 1.8 to 29.7 MHz, including WARC bands + 50 MHz.

Output Power: 1500+ Watts in SSB and CW modes on HF bands, 1000 Watts in SSB and CW modes on 50 MHz, 1000+ Watts in RTTY modes

Input Power: Typical 40 to 60 Watts for full power output.

Input Impedance: 50 ohms at SWR< 1.5: 1

Gain: 14 dB, Output Impedance: 50 Ohms, Maximum SWR: 2:1

SWR boost protection: automatic switch to STANDBY mode when reflected power exceeds 250 W

Intermodulation distortion: 32 dB of rated output power.

Harmonic Suppression:< -50 дБ относительно мощности несущей.

Lamp: GS-23B ceramic tetrode. Cooling: Centrifugal fan.

Power supply: 1 x 210, 220, 230 V - 50 Hz. Transformers: 1 toroidal transformer 2.3 KVA

Peculiarities:

Antenna switch for three antennas

Memory for errors and warnings - easy operation

Automatic anode current adjustment (BIAS) - no adjustment required after lamp replacement

Automatic adjustment of fan speed depending on temperature

Full QSK with silent relay

Smallest and lightest 1500W amplifier on the market

Dimensions (WxHxD): 390 x 195 x 370 mm, Weight: 22 kg

OM Power OM 2500 HF

The Russian-made GU84b tetrode is used to obtain an output power of up to 2700 Watts.

The amplifier uses a GU84B tetrode in a circuit with a grounded cathode (the input signal is fed to the control grid). The amplifier exhibits excellent linearity between the control grid bias voltage and the screen grid voltage. The input signal is fed to the control grid using a wideband transformer with an input impedance of 50 ohms. This input circuit provides an acceptable SWR value (less than 1.5:1) on all HF bands.

The output stage of the amplifier is a Pi-L circuit. The variable capacitor on ceramic insulators for circuit tuning and load matching is divided into two parts and designed specifically for this amplifier. This allows you to fine-tune the amplifier and easily return to previously tuned positions after changing the range.

The high anode voltage consists of 8 voltage sources of 300V/2A each. Each source has its own rectifier and filter. Safety resistors are used in the anode voltage circuit to protect the amplifier from overload. The grid voltage is stabilized by a circuit of IRF830 MOSFETs and is 360V/100mA. The control grid voltage -120V is stabilized by zener diodes.

Main technical characteristics of the power amplifier OM2500 HF

• Output Power: 2500 Watts in CW and SSB modes, 2000 Watts in RTTY, AM and FM modes
• < 2.0: 1 входное - 50 Ом при КСВ < 1,5:1
• RF gain: no less than 16 dB
• Protection units: when SWR, anode and grid currents increase, or when the amplifier is configured incorrectly, providing a soft start to protect fuses, blocking the switching on of dangerous voltages when the amplifier covers are removed
• Dimensions and weight (in working condition): 485x200x455 mm, 38 kg

OM Power OM2000 HF

The power amplifier is designed to operate on all HF bands from 1.8 to 29 MHz (including WARC bands) in all operating modes.

High frequency block:

The amplifier uses a GU-77B tetrode according to a circuit with a grounded cathode with excitation supplied to the control grid. The amplifier has excellent linearity because the control grid bias and screen grid voltage are well stabilized. The input signal is fed to the control grid through a broadband matching device with an input impedance of 50 Ohms. This solution ensures matching of the amplifier input with an SWR of no worse than 1.5:1 on any HF band.

Power supply

Using a unit made of relays and powerful resistors, a powerful rectifier is soft-started. The high-voltage unit is composed of eight sections providing 350 volts at a current of 2 amperes, each of which has its own rectifier and filter. Safety resistors are installed in the anode voltage circuit to protect the amplifier from overload.

Amplifier protection

Main technical characteristics of the OM2000 HF power amplifier

• Frequency range: all amateur radio bands from 1.8 to 29.7 MHz;
• Output power, no less: 2000 W in CW and SSB modes, 1500 W in RTTY, AM and FM modes
• Intermodulation distortion: no more than -32 dB from peak rated power.
• Harmonic suppression: greater than 50 dB peak rated power.
• Characteristic impedance: output - 50 Ohm, for asymmetric load, at SWR< 2.0: 1 входное - 50 Ом при КСВ < 1,5:1
• RF gain: no less than 17 dB
• Supply voltage: 230V – 50Hz, one or two phases
• Transformers: 2 toroidal transformers, 2KVA each
• Dimensions and weight (in working condition): 485x200x455 mm, 37 kg

OM Power OM2500 A

The power amplifier is designed to operate on all HF bands from 1.8 to 29 MHz (including WARC bands) in all operating modes. The OM2500 A automatically tunes to the transceiver frequency.

High frequency block

The amplifier uses a GU-84B tetrode according to a circuit with a grounded cathode with excitation supplied to the control grid. The amplifier has excellent linearity because the control grid bias and screen grid voltage are well stabilized. The input signal is fed to the control grid through a broadband matching device with an input impedance of 50 Ohms. This solution ensures matching of the amplifier input with an SWR of no worse than 1.5:1 on any HF band.

The amplifier output has a Pi-L circuit enabled. Each of the variable capacitors, designed to adjust the circuit and load, is made of ceramic insulators and is divided into two sections. This solution allows you to more accurately tune the amplifier and easily return to the previous settings after changing the range.

Power supply

The amplifier is powered by two two-kilowatt toroidal transformers.

Using a unit made of relays and powerful resistors, a powerful rectifier is soft-started. The high-voltage unit is composed of eight sections providing 420 volts at a current of 2 amperes, each of which has its own rectifier and filter. Safety resistors are installed in the anode voltage circuit to protect the amplifier from overload.

The voltage for the screen grid is provided by a parallel stabilizer assembled on high-voltage transistors of the BU508 type, which provides a voltage of 360 volts at a current of up to 100 mA. The bias for the control grid (-120 volts) is also stabilized.

Amplifier protection

The device provides continuous monitoring and protection of all circuits in case of disturbances in the operation of the amplifier. The protection unit is located on the control board installed in the subpanel.

Main technical characteristics of the power amplifier OM2500 A

• Frequency range: all amateur radio bands from 1.8 to 29.7 MHz;
• Output power, no less: 2500 W in CW and SSB modes, 2000 W in RTTY, AM and FM modes
• Intermodulation distortion: no more than -32 dB from peak rated power.
• Harmonic suppression: greater than 50 dB peak rated power.
• Characteristic impedance: output - 50 Ohm, for asymmetric load, at SWR< 2.0: 1, входное - 50 Ом при КСВ < 1,5:1
• RF gain: no less than 17 dB
• Manual or automatic setting
• Tuning speed on the same range:< 0.5 сек.
• Tuning speed when tuning to another range:< 3 сек.
• Supply voltage: 230V – 50Hz, one or two phases. Transformers: 2 toroidal transformers, 2KVA each
• Protection units: when SWR, anode and grid currents increase, when the amplifier is configured incorrectly, providing a soft start to protect fuses, blocking the switching on of dangerous voltages when the amplifier covers are removed
• Dimensions and weight (in working condition): 485x200x455 mm, 40 kg

OM Power OM3500 HF

The OM3500 HF power amplifier is designed to operate on all HF bands from 1.8 to 29 MHz (including WARC bands) in all operating modes. The amplifier has a GU78B ceramic tetrode.

The amplifier uses a GU78B tetrode in a circuit with a grounded cathode (the input signal is fed to the control grid). The amplifier exhibits excellent linearity between the control grid bias voltage and the screen grid voltage. The input signal is fed to the control grid using a wideband transformer with an input impedance of 50 ohms. This input circuit provides an acceptable SWR value (less than 1.5:1) on all HF bands. The output stage of the amplifier is a Pi-L circuit. The variable capacitor on ceramic insulators for circuit tuning and load matching is divided into two parts and designed specifically for this amplifier. This allows you to fine-tune the amplifier and easily return to previously tuned positions after changing the range.

The amplifier's power supply consists of two 2KVA toroidal transformers. The soft start mode occurs using relays and resistors.

Amplifier protection:

Constant monitoring and protection of anode and grid voltages and currents is carried out in case of incorrect amplifier settings, a soft start mode is implemented to protect fuses.

Technical characteristics of the power amplifier OM3500 HF:

• Frequency range: all amateur radio bands from 1.8 to 29.7 MHz;
• Output Power: 3500 Watts in CW and SSB modes, 3000 Watts in RTTY, AM and FM modes
• Intermodulation distortion: better than 36 dB below peak rated power.
• Harmonic Rejection: Better than 55 dB below peak rated power.
• Characteristic impedance: output - 50 Ohms, for asymmetric load, input - 50 Ohms at SWR< 1,5:1
• RF Gain: Typical 17 dB
• Supply voltage: 2 x 230V – 50Hz, one or two phases
• Transformers: 2 toroidal transformers, 2.5 KVA each
• Dimensions and weight (in working condition): 485x200x455 mm, 43 kg

RM KL500

Amplifier RM KL500 HF range (3-30) MHz, input power 1-15 W, output 300 W with electronic switching technology and polarity reversal protection. It has six output power levels and a 26 dB antenna preamplifier.

Frequency: HF

Voltage: 12-14 Volts

Current consumption: 10-34 Amps

In. power: 1-15 W, SSB 2-30 W

Exit Power: 300W Max (FM) / 600W Max (SSB-CW)

Modulation: AM-FM-SSB-CW

Six power levels

Fuses: 3×12 A

Size: 170x295x62 mm

Weight: 1.6 kg Price (approximately in the Russian Federation) = $340

YAESU VL-2000

Great power combined with high reliability.

8 massive CMOS field-effect transistors of the VRF2933 type, connected in a push-pull circuit, provide the necessary output power in the range from 160 to 6 m. Two large fans with a continuous rotation speed control system effectively cool the PA and low-pass filter unit, providing years of reliable and silent operation .

Two large pointer instruments.

The left instrument shows the output power or SWR. Right – current consumption and supply voltage.

The monitoring system provides reliable and quick troubleshooting in the system.

In high-power devices, mains voltage fluctuations, temperature violations, high SWR levels, and exceeding the level of the RF drive signal at the input are monitored.

The built-in automatic high-speed antenna tuner matches your antenna to an SWR level of 1.5 or better in less than 3 seconds (according to the passport).

Two input and four output connectors allow integrated selection of the transmitter and the required antenna.

For example, two input connectors allow you to connect an HF transceiver to the first (INPUT 1), and a 6 m range transceiver to the second (INPUT 2). In this case, the output connectors can be connected to various antenna switching devices available at the station. Automatic selection of the required antenna can be performed for the transmitter connected to input 1 (INPUT 1), often eliminating the need for additional antenna switches. When the “DIRECT” toggle switch located on the rear panel is turned on, the amplified signal from input 2 (INPUT 2) is fed directly to the “ANT DIRECT” connector, bypassing the output switching system. In addition, the VL-2000 PA can be used in the SO2R system.

Automatic range switching for quick transitions.

Most modern Yaesu transceivers allow you to exchange data about the current range between the transceiver and the VL-2000 PA, which allows you to automatically change the range in the PA when you change the latter in the transceiver. To automatically change the range when using other types of transmitters, the VL-2000 PA has an automatic range detection function using a built-in frequency meter, which ensures an immediate change of range the first time an RF signal is applied to the PA input.

Specifications

• Range: 1.8-30; 50-54 MHz
• Antenna switch: ANT 1-ANT 4, ANT DIRECT
• Power: (1.8-30 MHz) 1.5 KW, (50-54 MHz) 1.0 KW
• Consumption: 63 A
• Supply voltage 48 V
• Types of work: SSB, CW, AM, FM, RTTY
• Range switching: manual/automatic
• Output transistor: VRF2933
• Output stage operating mode: Class-AB, Push-pull, Power Combine
• Spurious emissions: -60 dB
• Input power: 100 to 200 W
• Temperature: -10 +40 C
• Dimensions 482x177x508 mm, Weight: 24.5 kg
• Power supply: Output voltages: +48 V, +12 V, -12 V. Output current: +48 V 63 A, +12 V 5.5 A, -12 V 1A,
• Dimensions: 482x177x508 mm. Weight: 19 kg

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Updated: 02/06/2023

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