Radio receiver Ocean-209
Basic technical data of the Ocean-209 radio receiver. The Ocean-209 portable transistor radio receiver of the second class is designed to receive transmissions from radio stations operating with amplitude modulation in the DV, SV and five HF sub-bands, as well as with frequency modulation in the VHF range. The Ocean 209 radio receiver has an internal antenna for receiving radio stations in the DV and SV bands and a whip telescopic antenna for receiving in the HF and VHF bands. For smooth, separate adjustment of lower and higher sound frequencies, two tone controls are installed.
Sensitivity when receiving internal ferrite antenna in the LW range - no worse than 0.5 mV/m, in the NE range - 0.3 mV/m. Sensitivity when receiving with a telescopic antenna in the HF5 range is no worse than 150 µV; KV4-KV1 -85 μV; VHF - 20 µV Selectivity over the adjacent channel in the DV and SV ranges - no worse than 34 dB. The attenuation of the mirror channel in the LW and MW range is no more than 54 dB, in the HF range - 16 dB and VHF - 26 dB. The rated output power of the Ocean 209 radio is -0.5 W. The band of reproduced audio frequencies in the DV, GB and KB ranges is 125...4000 Hz, in the VHF range - 125...10,000 Hz.
The ocean-209 radio receiver is powered by six elements of type 373 (Mars, Saturn) or from an alternating current mains voltage of 127 or 220 V. The operating time of the ocean 209 radio receiver from one set of type 373 batteries at an average volume is at least 100 hours. Overall dimensions 367X254x124 mm. The weight of the Ocean 209 radio without power supply is 4.0 kg.
Frequency converter The Ocean 209 radio receiver is assembled on a transistor V2 type GT31ZA using a combined circuit. The local oscillator operates according to a three-point capacitive circuit. The local oscillator circuit L4C16C17C7 is connected in parallel with the coil L5 of the intermediate frequency circuit. For positive feedback of the radio receiver ocean 209, necessary for the operation of the local oscillator, is carried out through capacitor C13. To correct the phase and attenuate the 10.7 MHz IF signal, an inductor L and a capacitor SP are included in the emitter circuit of transistor V2. Automatic frequency adjustment of the Ocean 209 V radio receiver (AFC) is carried out by changing the capacitance of the D902 type varicap V2, connected in parallel to the local oscillator circuit. The control voltage is supplied to the varicap from the output of the fractional detector.
Block KSDV The Ocean 209 AM radio receiver consists of a drum with a set of band strips, a magnetic antenna assembly and a three-section KPI Cl-1, C1-2 and C1-3. The circuits of the input circuits, RF amplifier and local oscillator are installed on the strips. The coils of the input circuits of the DV (L3) and MV (N) ranges and the corresponding communication coils L4 and L2 are wound on the ferrite rod of the magnetic antenna. When the DV is operating, the inductance of the input circuit is made up of series-connected coils L and L3, and on the CB, the coil L3 is short-circuited. The external antenna of the ocean radio receiver 209 is connected to the input circuits in the DV and SV ranges through capacitor C122, and in the KB range through C121. The connection of the telescopic antenna with the input circuits KB is autotransformer, carried out through a capacitor C67 and. throttle C8. The choke eliminates the shunting influence of the input circuits of the KB range of the block on the input circuit of the VHF block.
To start…
Some time ago, I came into my hands with a rather battered, but still sometimes properly working OCEAN 209 receiver. Judging by its condition, the receiver flew from the table to the floor as much as a highly qualified pilot flew.
The thing is, in principle, not bad - 5 HF channels, there are SW and LW, and, most valuable, VHF. In addition, the receiver has an AFC system - automatic frequency adjustment. But, enough of the chatter about what is and what is not, let’s get down to analysis.
Analysis?! - it's fast!
As one fairly good radio technician said: “I disassemble any device with three tools: a screwdriver, a sledgehammer and a crowbar. Only without subsequent assembly...” We only need the first one (hide the rest away so as not to destroy the device in a fit of rage).
So, unscrew the 4 screws from the back and remove the cover.
Next we need to unhook the range shift knob. It is held on by two studs. Unscrew the pins and pull out the handle with a sharp movement. Now we can freely remove the wooden case. Only the front side remains.
Remove the control handles (if they still exist). Unscrew the 4 aluminum ties and the screw that connects the antenna input terminal to the antenna. Next, carefully release the front cover.
All that remains is to unscrew the speaker, and that’s it.
Then we can get to the point: what we want from him. For example, I initially wanted to do 5 things: replace the speaker, crank up the amplifier to 10 W, improve the backlight, convert VHF1 to VHF2 and bring it into a little better shape.
Of course, later I left the original amplifier, but replaced all the variable resistors.
VHF 1 to VHF2
First, stock up on literature: Radio magazine, 1977, No. 10, page 36. There is a description and diagram of the receiver.
There are 2 VHF bands - VHF1 and VHF2, respectively. Modern radio stations mostly operate on VHF2 (FM) - 88-108 MHz. Converting a VHF unit to FM is not an easy task. But the Internet is full of descriptions of how this can be done, and therefore I will not retell what is already on other sites. Just type into a search engine a query like “VHF on FM in Ocean 209” and you’ll end up with a bunch of topics on how it’s all done. Basically this means unsoldering excess containers, replacing some with other ratings and adjusting the circuits by tightening the cores. One of the cores is being replaced with a ferrite one (for reference: they are all brass). The range is adjusted by the L 4 circuit, the sensitivity is adjusted by the L 3 circuit, and the input is adjusted by the L 1 and L 2 circuits (if I’m not mistaken, they are wound on the same frame).
VHF block diagram
I strongly advise you to follow this link: Restructuring the Ocean on FM. There is a complete and accurate description of the actions on the VHF unit.
And further. When I was disassembling and remaking the VHF unit, I noticed that the design of the unit may differ from what is shown in the diagram.
By the way, while you haven’t figured anything out yet, I want to give you some advice: the system for tuning to a specific radio station is old (that is, in threads). To avoid problems later, it is better to fix it on the rollers with tape or adhesive tape.
And he is alive and glowing...
The backlight can be LED. It is brighter and consumes less, but do not overdo it - excessive load on the transformer does not bring anyone any harm.
Positive voltage is applied to the common wire (chassis). Be careful.
Sounds of radio waves
I didn't change the acoustics. I replaced the old variable resistors with new ones - this will increase the service life of the radio (in short, I won’t look there any time soon).
Now the device's speaker. We remove it and inspect it carefully. If the speaker cone is torn, it is advisable to replace it with a new one - any suitable size, 1-2 W power, with a resistance of 8 ohms. You can install it with a resistance of 4 ohms, but perhaps the output stages will heat up terribly, which over time can lead to failure of the output stage transistors.
I was not lucky. The previous owners of the receiver managed to destroy the speaker. I don’t know how it still works, but I still have to change the speaker.
If the speaker magnet does not quite fit into the housing and touches any parts, then it is better to completely cover it with insulating material.
If the built-in amplifier is not satisfactory, then I advise you to assemble it on microcircuits that have inverted input and output (for example: TEA 2025b, TDA 2822, etc.) and the power supply does not exceed 9 V.
Do not forget! The common wire has a polarity that is not negative, but vice versa! Don't make mistakes when designing!
The appearance is the most interesting thing.
The most interesting thing is, as always, at the end. (Oh, and the article will end soon...).
The appearance of the receiver is an individual thing. Of course, you can insert it into a case made of modern materials, but still this will not be what is needed. Therefore, I left the old body - just properly, washed it off any dirt, restored the front grille (in the process, the speaker was damaged by the fork), screwed all the control knobs into place.
By the way, about the pens. Radio parts stores sell a fairly large assortment of control knobs, so this should not be a problem.
It is advisable to cover the wooden part with two layers of special varnish.
This article is not intended to teach how to repair this receiver, it is aimed at encouraging the repair and restoration of Soviet equipment and just directs where necessary. If you still have problems, write to the profile or leave comments here on the site.
And how to repair a stylish Soviet Hi-Fi amplifier "Radiotekhnika U-101 stereo"!
Basic technical data radio ocean 209. The Ocean-209 portable transistor radio receiver of the second class is designed to receive transmissions from radio stations operating with amplitude modulation in the DV, SV and five HF sub-bands, as well as with frequency modulation in the VHF range. The Ocean 209 radio receiver has an internal antenna for receiving radio stations in the DV and SV bands and a whip telescopic antenna for receiving in the HF and VHF bands. For smooth, separate adjustment of lower and higher sound frequencies, two tone controls are installed.
Sensitivity when receiving on an internal ferrite antenna in the DV range is no worse than 0.5 mV/m, in the SW range - 0.3 mV/m. Sensitivity when receiving with a telescopic antenna in the HF5 range is no worse than 150 µV; KV4-KV1 -85 μV; VHF - 20 µV Selectivity over the adjacent channel in the DV and SV ranges - no worse than 34 dB. The attenuation of the mirror channel in the LW and MW range is no more than 54 dB, in the HF range - 16 dB and VHF - 26 dB. The rated output power of the Ocean 209 radio is -0.5 W. The band of reproduced audio frequencies in the DV, GB and KB ranges is 125...4000 Hz, in the VHF range - 125...10,000 Hz.
Nutrition radio ocean 209 is carried out from six elements of type 373 (Mars, Saturn) or from an alternating current network with a voltage of 127 or 220 V. The operating time of the Ocean 209 radio receiver from one set of batteries of type 373 at an average volume is at least 100 hours. Overall dimensions are 367X254x124 mm. The weight of the Ocean 209 radio without power supply is 4.0 kg.
Electrical circuit diagram ocean radio 209. VHF unit. The input circuit of the VHF unit consists of a broadband circuit with a bandwidth of about 8 MHz. The signal from the telescopic antenna through capacitors C67 and C65 of the HF-IF unit is supplied to the input circuit L2C1C2 through a coupling coil. The signal voltage from the capacitive divider is supplied to the emitter of a type VI transistor GT313B of a high-frequency amplifier assembled according to a common base circuit. Its load is an oscillatory circuit L3C4C6C7, tuned to the frequency of the received signal by a variable capacitor C7 (the second section of this capacitor is used to tune the local oscillator circuit). A VI type D20 limiting diode is connected in parallel to the circuit, protecting the frequency converter from overload at a high level of input signals. To prevent the ocean 209 radio diode from shunting the circuit at low signal levels, an initial bias voltage of about 0.2 V is supplied to it from resistor R4.
The Ocean 209 radio frequency converter is assembled on a V2 transistor of the GT31ZA type using a combined circuit. The local oscillator operates according to a three-point capacitive circuit. The local oscillator circuit L4C16C17C7 is connected in parallel with the coil L5 of the intermediate frequency circuit. For positive feedback of the radio receiver ocean 209, necessary for the operation of the local oscillator, is carried out through capacitor C13. To correct the phase and attenuate the 10.7 MHz IF signal, an inductor L and a capacitor SP are included in the emitter circuit of transistor V2. Automatic frequency adjustment of the Ocean 209 V radio receiver (AFC) is carried out by changing the capacitance of the D902 type varicap V2, connected in parallel to the local oscillator circuit. The control voltage is supplied to the varicap from the output of the fractional detector.
In the Ocean 209 radio receiver, the mixer load is a double-circuit bandpass filter L5C14 and L6C18, tuned to an intermediate frequency of 10.7 MHz. The FM IF voltage is supplied through coil L7 and separating capacitor C69 to the base of the transistor of the first stage of the FM IF.
The KSDV block of the Ocean 209 AM radio receiver consists of a drum with a set of band strips, a magnetic antenna assembly and a three-section KPI Cl-1, C1-2 and C1-3. The circuits of the input circuits, RF amplifier and local oscillator are installed on the strips. The coils of the input circuits of the DV (L3) and MV (N) ranges and the corresponding communication coils L4 and L2 are wound on the ferrite rod of the magnetic antenna. When the DV is operating, the inductance of the input circuit is made up of series-connected coils L and L3, and on the CB, the coil L3 is short-circuited. External antenna radio ocean 209 it is connected to the input circuits in the DV and MV ranges through capacitor C122, and in the KB range - through C121. The connection of the telescopic antenna with the input circuits KB is autotransformer, carried out through a capacitor C67 and. throttle C8. The choke eliminates the shunting influence of the input circuits of the KB range of the block on the input circuit of the VHF block.
The AM and FM RF-IF section contains an AM RF amplifier, an AM local oscillator, a ring mixer, an AM and FM IF amplifier, and AM and FM signal detectors.
The high-frequency amplifier of the AM radio receiver Ocean 209 is assembled on a transistor V18 type GT322V according to a circuit with autotransformer coupling with a circuit and inductive coupling with a mixer. The RF amplifier load is located in the KSDV block. The restructuring of the circuits in the radio receiver ocean 209 is carried out by a variable capacitor C1-2. On the AM bands, in addition to the KB 1 and KB2 subbands, high-frequency chokes L2, L4, L6 or L7, located in the KSDV block, are connected in parallel with the emitter resistor R19 through the capacitor C70. This ensures additional attenuation of interference from mirror and adjacent channels and equalization of sensitivity across the range. The RF signal, amplified by transistor V18, is fed to the mixer.
The AM frequency converter in the Ocean 209 radio receiver is made according to a circuit with a separate local oscillator. The local oscillator is assembled on a transistor V5 type GT322V using an inductive three-point circuit and with a transformer connection to the mixer. A feature of the frequency converter circuit is the use of a ring mixer on diodes V6...V9 of the D9V type, made according to a balanced circuit. The diodes are connected according to a ring circuit with one-way conductivity (Fig. 59). The Ocean 209 radio mixer has a symmetrical input for supplying signal voltage from the HF amplifier circuit L14 (points C - C). The local oscillator voltage is supplied from coil L15 to the circuit points (g-g). Coil L53 with a middle output acts as a phase shifter. The local oscillator current branches out, forming the currents of the corresponding arms of the balanced frequency converter. With complete symmetry of the arms at the IF - IF points, the local oscillator voltage is zero. The conductivity of the diodes in the ocean 209 radio receiver changes in time with the local oscillator frequency so that zero and maximum conductivity values occur simultaneously, therefore the signal current between the IF - IF points changes in magnitude (with the local oscillator frequency). As a result of this, the balance of the circuit is disrupted and components of the difference f g -fc and total fg + fc frequencies appear at the output of the mixer (IF-IF points). The oscillating circuit L52C78C79, inductively coupled to the coil L53, is tuned to the frequency fg -fc, i.e. 465 kHz. Therefore, only the difference intermediate frequency voltage will be supplied to the base of transistor V2 of the first stage of the AM amplifier.
The use of such a mixer made it possible to significantly increase the noise immunity of the AM path and ensure good isolation of the local oscillator from the input of the radio receiver. In addition, such a mixer circuit makes it possible to exclude a filter for attenuating signals with a frequency equal to the intermediate one from the radio receiver circuit.
The intermediate frequency amplifier of the AM path consists of three amplification stages and is assembled using transistors V2, UZ, V4 of the GT322A type according to a common emitter circuit. The load of the first stage is a four-circuit lumped selection filter (FSS) L57C84, L58C89, L59C90, L60C95C96 with external capacitive coupling through capacitors C86, C88 and C93. From capacitive divider C94, C95 of the last FSS circuit, the IF signal voltage is supplied to the base of transistor V3. A single-circuit bandpass filter L63C101C102 is connected to the collector circuit of this transistor in series with the FM filter. The IF voltage in the capacitive divider C101, C102 is supplied to the base of transistor V4 through the tap of coil L64. The load of this cascade is the L67CV13 circuit with the L68 coupling coil. An AM signal detector assembled on a V13 diode of type D9B is included in the circuit according to a sequential circuit. The low audio frequency voltage from the divider R52, R51, R53 and through the capacitor C115 is supplied to the volume control R60.
The intermediate frequency amplifier of the FM path consists of four stages. The signal from the output of the VHF unit goes to the base of transistor VI. The load of the cascade is the bandpass filter L49C71, L51C76, coupling coil L50 and coupling capacitor C75. The collector circuit of the second stage of transistor V2 includes a bandpass filter L54C81, L56C92, a coupling coil L55 and a coupling capacitor C87. Subsequent stages are assembled on transistors V3, V4. The loads are, respectively, filters L61C98 and L64C105, coupling coil L62, coupling capacitor C100, filters L66C111, L69C118, coupling coil L65 and coupling capacitor CJ16. The connection of the IF filters with the collector of the previous and the base of the subsequent transistors is weakened due to the fact that voltage is supplied and removed from part of the turns of the coils. In the collector circuit of all four transistors, resistors R18, R26, R37, R49 are turned off, which reduce the detuning of the primary circuits of bandpass filters at large signals at the input of the cascade and increase the stability of the operation of the amplifier cascades.
The frequency detector of the radio receiver Ocean 209 is assembled on diodes V14, V15 of type D20 according to the circuit of a symmetrical fractional detector. The detected FM signal is removed from the midpoint of resistors R55 and R58 and through the pre-emphasis chain R56С142 and the separating capacitor C117 is supplied to the ULF input. From the same point, the direct component through the R90C143 filter is supplied to the V2 varicap of the VHF unit to automatically adjust the local oscillator frequency.
The Ocean 209 radio receiver uses a highly efficient combined AM-FM AGC system based on the relay principle. It covers the RF amplifier for AM signals and the IF amplifier. The AGC detector is assembled on diodes V11 type D103 and V12 type D9B according to a voltage doubling circuit. An alternating voltage with a frequency of 465 kHz or 10.7 MHz is supplied to the AGC detector from the output of the IF amplifier. The rectified voltage of the Ocean 209 AGC radio receiver is supplied to the base of transistor V3 through filter R47C110C106 and resistor R44. When receiving weak signals, diodes VII and V12 are open. When the amplitude of the alternating voltage supplied from the output of the IF amplifier to the diodes exceeds the constant forward bias across them, the diodes close and the AGC begins to work. In this case, as the signal increases, the bias at the base of transistor V3 changes so that its emitter current and the gain of the stage on this transistor decrease. The decrease in current is recorded by an IP dial indicator connected to the emitter circuit of transistor V3. From resistor R28 in the emitter circuit of transistor V3, the voltage resulting from a change in the emitter current is supplied through filter R23C77 and resistor R21 to the base of transistor VI, and through filter R25C74 and resistor R17-: to the base of transistor V18, the gain of the stages on these transistors is also reduced .
To ensure normal operation of the HF and IF paths of the ocean 209 radio receiver at a reduced supply voltage to 5...6V, the AM local oscillator, the entire VHF unit and the base circuits of all transistors in the HF-IF unit are powered by a stabilized voltage. The voltage stabilizer is assembled on transistors V6 type MP35, V7 type MP39 and diode V10 type 7GE2A-K. The regulating element in this circuit is transistor V7. Diode V10 serves to stabilize the reference voltage at the emitter of transistor V7. A stabilized voltage of 4.4V is removed from the collector of transistor V6.
The ocean 209 low-frequency radio amplifier is six-stage, assembled with eight transistors. The first two stages are assembled on MP40 type transistors V10 and VII. Regime and temperature stabilization of these cascades is carried out due to deep negative feedback on direct current by resistors R61, R62 and R66. The third and fourth stages are assembled on transistors V12 type MP40 and V13 type KT315B, connected according to a common emitter circuit. At the input of the third stage, tone controls are turned on for the upper (resistor R71) and lower (resistor R68) audio frequencies.
The pre-terminal stage of the ULF - phase inverter on transistors V14 type MP40 and V15 type MP37 is built according to a sequential push-pull circuit. Phase inversion is carried out through the use of transistors with different conductivities.
Final stage radio ocean 209 assembled on transistors V16 and V17 type P213B according to a sequential push-pull circuit with a transformerless output. Its load is the dynamic head of a loudspeaker type 1GD-48. The connection between the pre-terminal stage and the final stage is direct, which improves the frequency response of the amplifier in the low-frequency region. Resistors R84 and R85, respectively included in the base circuits of transistors V16 and V17, partially compensate for the influence of the spread in the parameters of these transistors on the operating mode of transistors VT3 and V.14. To balance the push-pull part of the circuit, use a variable resistor R82. Temperature stabilization of the final stage mode is carried out by thermistor R81, connected to the circuit of the base divider of the phase-inverted stage. The low-frequency amplifier contains intra-stage feedback, as well as a number of decouplings along the power supply circuit that stabilize its operation.
Negative DC feedback of the radio receiver Ocean 209 is carried out from the ULF output through resistor R83 to the emitter circuit of transistor V12. To reduce the harmony coefficient, AC feedback is introduced using the R80C136 chain. The required drop in the frequency response is carried out by feedback capacitor C135, connected between the base and collector of transistor V13. The bias at the base of transistor V12 is set by variable resistor R78. The R75C133 chain acts as a filter.
To power the Ocean 209 radio from a 127/220V AC mains, it includes a power supply, which is a full-wave rectifier assembled on D226D type V1...V4 diodes using a bridge circuit with a C66 capacitive filter and an electronic voltage stabilizer. A DC amplifier is assembled on transistor V9 type MP39, and a control cascade is assembled on transistor V8 type P213A. The feedback voltage is supplied to the base of transistor V9 from variable resistor R8. Using this resistor, a stabilized voltage of 9V is established in the Ocean 209 radio. The stabilized voltage is removed from the emitter of transistor V8. Switching between 127 and 220V networks is carried out by rearranging the block, which is located on the back wall of the radio.
You can connect a tape recorder to the Ocean 209 radio receiver through a standard low-frequency connector of the HZ type SGZ, connected to the output of the detector, for recording or playback through the dynamic head of the loudspeaker. Also, in the Ocean 209 radio receiver, you can connect a small-sized TM-4 telephone through the X6 socket, while the loudspeaker head of the Ocean 209 radio receiver is automatically turned off.
This experience is for a beginner who has achieved the moral right to be called a “teapot” from electronics. That is, someone who already knows how to turn on a soldering iron, who understands the differences between radio components, well, at least in appearance, and who knows that these are electronic components. At the same time, he has an enduring desire to bring “to life” one of the electronic devices gathering dust in his closet, and with the condition of obligatory success. Let's start with an old Ocean-209 radio, perhaps even an antique one. It works, but it's simply not possible to use it anymore. The reason is, for example, not entirely adequate sound reproduction. The first thing you need to learn and remember throughout the entire event is that you can’t complete the repair “in one sitting,” so do everything thoroughly and as the repair progresses, don’t really rely on your excellent memory, but take notes and even a photo of what will have to be done in the process. I started by searching the Internet for information, and in full, about the radio receiver being restored. These are operating instructions, a diagram of the arrangement of blocks and components on the chassis of the radio receiver, a circuit diagram, wiring diagrams of printed circuit boards and a list of components and parts used in it.
After reading the instructions and studying the radio diagrams, I unscrewed the screws and removed the back cover, side housing and front panel.
I didn’t burden myself with super-complicated tasks, but simply, as most electronics luminaries advise, I decided to check the serviceability of electrolytic capacitors and variable resistors and replace the unusable ones. To do this, I removed separate low-frequency amplifier and power supply units from the chassis. When performing this operation, it is best to cut the connecting wires in half and put a piece of cardboard with a written serial number on each end. There will be two cards, but the number on them is the same. As for the wires, you still need to install new ones during assembly.
I started with the power supply, as the most understandable unit. From the circuit diagram it is clear that its transformer is designed to work both with a mains voltage of 220 V and 127 V. I did not live at the time when sockets with a voltage of 127 V were encountered, so this “function” of power is perceived by me as an insidious legacy, from which you need to get rid of :)
Having measured the resistance of the input windings of the transformer, I identified the middle tap for 127 V, bit off the bare end, wound it in a ring and insulated it. The presence and location of electronic components is especially clearly visible in the wiring diagram. There is only one electrolyte that interests me. I unsolder it, discharge it and measure the capacitance - it’s not enough to reach the norm of 60 uF, but the ESR probe shows the minimum allowable resistance. Therefore, I decide to put it in place and, in parallel to it, solder another capacitor with a capacitance of 100 μF, slightly larger than the missing one, but for the same voltage - 25 V. Before installation, the new component is necessarily checked to ensure that the capacitance corresponds to the nominal value, and ESR to acceptable value. I did it, applied 220 V mains voltage to the power supply and measured the output received - everything is normal, the power supply is working.
Now the sound amplifier. It's getting more serious here...
On the board I find seven electrolytic capacitors K50-12, very ancient in appearance. I move the wiring diagram closer to me and unsolder one leg from the board for each container. Naturally, where possible. Where not, the capacitor is completely soldered off.
You can unsolder everything completely, there is an installation, but it may not be there, and then it will save a lot of time and nerves.
