To start…
Some time ago, a rather shabby, but still sometimes properly working OCEAN 209 receiver fell into my hands. Judging by the condition, the receiver flew from the table to the floor as much as a highly qualified pilot flew.
In principle, the thing is not bad - 5 HF channels, there are SV and LW, and, most valuable, VHF. In addition, the receiver has an AFC system - automatic frequency control. But, enough chatting about what is and what is not, let's proceed to the analysis.
Parsing?! - it's fast!
As one fairly good radio engineer 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 that you don’t destroy the device in a fit of rage).
So, unscrew the 4 screws on the back and remove the cover.
Next, we need to unhook the range switch knob. It is held on by two pins. We unscrew the studs and pull out the handle with a sharp movement. Now freely remove the wooden case. Only the front side remains.
Remove the control knobs (if they still exist). We unscrew 4 aluminum ties and a screw that connects the antenna input terminal with the antenna. Next, carefully remove the front cover.
It remains only to unscrew the speaker, and that's it.
Then you can go to the very essence: what we want from him. For example, I originally wanted to do 5 things: replace the speaker, crank up the amplifier to 10 watts, improve the backlight, convert VHF1 to VHF2 and bring it into a godly form.
Of course, subsequently the amplifier left the native one, but replaced everything variable resistors.
VHF 1 to VHF2
To get started, stock up on literature: Radio magazine for 1977 No. 10, page 36. There is a description and diagram of the receiver.
There are 2 VHF bands - respectively VHF1 and VHF2. Modern radio stations for the most part sit on VHF2 (FM) - 88-108 MHz. Rebuilding a VHF unit to FM is no 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 in a query like "VHF to FM to Ocean 209" into a search engine, and as a result, a bunch of topics will come up on how it's all done. Basically, this is soldering extra containers, replacing some with other denominations and adjusting the contours by twisting the cores. There is a replacement of one of the cores with a ferrite one (for reference: they are all brass there). 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 one frame).
Scheme of the VHF block
I strongly advise you to follow this link: Rebuilding 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 redoing the VHF unit, I noticed that the unit may be structurally different from what is drawn in the diagram.
By the way, while you haven’t sorted anything out yet, I want to give advice: the system for tuning to a specific radio station is old (that is, with threads). So that there are no problems later, it is better to fix it on the rollers with adhesive 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 - an excessive load on the transformer did not bring anyone to good.
Positive voltage is applied to the common wire (chassis). Be careful.
Sounds of radio waves
Didn't change the acoustics. I changed the old variable resistors to new ones - this will increase the life of the radio (in short, I will not look there soon).
Now the speaker of the device. Take it off and take a look at it. If the speaker cone is torn, it is advisable to replace it with a new one - any one that is suitable in size, with a power of 1-2 W, with a resistance of 8 ohms. It can also be supplied with a resistance of 4 ohms, but it is possible that the output stages will heat up in a terrible way, which over time can lead to failure of the output stage transistors.
I was not lucky. The previous owners of the receiver managed to slam the speaker into nothing. I don’t know how it still works, but you still have to change the speaker.
If the speaker magnet does not quite fit into the case and touches any parts, then it is better to completely cover it with an insulating material.
If the built-in amplifier does not suit you, then I advise you to assemble on such microcircuits that have an 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 not negative, but vice versa! Make no mistake when designing!
Appearance - the most interesting.
The most interesting - 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 it will not be what you need. Therefore, I left the old case - just as it should, washed it off any dirt, restored the front grille (in the process, the speaker suffered from the plug), screwed all the control knobs into place.
By the way, about the handles. 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 the repair of this receiver, it is aimed at encouraging the repair and restoration of Soviet technology and only directs where necessary. If you still have problems - write to the profile or leave comments here on the site.
And for the repair of a stylish Soviet hi-fi amplifier"Radio engineering U-101 stereo"!
I'll start with a quote from a forum on a site recently discovered (accidentally) on the Internet "Domestic radio engineering of the twentieth century" :
“Spring has begun, I go to the country. 20 km from the city. "Ocean", rebuilt by me, also confidently accepts everything, as well as in the city. I remember taking it with me BEFORE perestroika ("Ocean") and listening to VHF stations, so in the kung he did not receive anything, and now he catches everything in the kung .... Satisfied.
This statement by a radio amateur from Kaliningrad was preceded by a discussion on forum topic “Ocean-209. Rebuilding VHF to FM". The problem, as you can see, is not new - although such topics became especially relevant only in the 90s, when many stations appeared with FM in the range of 87.5 - 108 MHz: it is also VHF-2 or FM band (although the last abbreviation for the words F requency M odulation is not entirely correct, because it translates as “frequency modulation ...”)
Cheap imported (often made in China) receivers do not allow you to get high-quality sound reproduction (in a word, “soap dishes”), and the “old” receivers of Russian (Soviet) production did not have the above range, although some, according to acoustic data, will give odds to many imported samples. For example, a number of class 0-1-2 radios had a wooden case (the same Okean-209, Meridian-206 or Leningrad-002), which, of course, gave a gain in playback quality ... I'm not talking about reliability and maintainability of our "mastodons" ...
Their time has passed. And it's a shame to throw it away. Especially for radio amateurs. And you can remake (rebuild) to amateur bands. And maybe not amateur. For example, I don't know of analogs from a number of imported receivers that would be able to sound a small suburban area using a 1-2 watt speaker with acceptable playback low frequencies. And "Oceans", "Meridians", "VEFs", "Speeds" ... - they can. And the cucumber harvest is better ...
As an example, I will give a method for restructuring the Okean-209 VHF unit from the range of 65.8 ... 73 MHz to the range of 87.5 ... 108 MHz.
On the site, the address of which is given at the beginning of the article, in addition to the alteration that I got, there are other options for alterations according to the schemes of different years of production, including the data of the VHF-2-2C (E) block for receivers manufactured for export .
The designations of the elements changed in the process of alteration in the VHF unit on all the principal and wiring diagrams of Okeanov-209 known to me do not differ. However, it is best to use the circuit that came from the factory with a particular receiver (when purchased). If the passport scheme has not been preserved, then you can use any other one downloaded from the Internet, or from those that are given on the forum. In many reference books, diagrams and descriptions of receivers with a VHF-2-2C unit are more often found. At the time of the most massive production of "Oceans-209" (late 70s - early 80s), the Minsk software "Horizont" most often completed them with a block VHF-2-2E-03. Figure 1 shows a diagram of this block.
Fig.1
So, without going into theory, I will briefly outline the essence of perestroika.
The task is to receive at the receiver FM band(hereinafter, for convenience, we will call the range 87.5 ... 108 MHz exactly like that - the FM range ...)
The circuit is superheterodyne, the intermediate frequency is 10.7 MHz. There is an IF, a detector and an ultrasonic frequency converter in the receiver, they do not need to be adjusted or rebuilt.
To get an IF for the FM band, you need to rebuild the mixer in the receiver (in the VHF unit) combined with the GPA on transistor T2 to these same 10.7 MHz above the band frequency (circuit L4, C16, C7). That is, so that the local oscillator tuning frequency is in the range from 98 to 118 MHz. In addition, for the FM frequency band, it is necessary to tune the broadband input circuit (L2, C1, C2) and the resonant UHF circuit at T1 (L3, C6, C7) to a higher frequency.
To do this, it is necessary to change the capacitances in the indicated circuits (it's easy - to replace the capacitors with others, with a different rating) and inductance (by rotation, shortening, selection of ferrite or brass cores, or unwinding the turns of the circuit coil - one or two turns, no more).
To increase the operating frequency, which we need to do, both the capacitance and inductance of the circuits should be reduced. There are other features, such as, for example, stretching the range (“laying” the stations of your region “on the scale”, changing the capacity of interstage communication, AFC ...). We will not go into such details - who wants (or knows) - he will figure it out. For simplicity, I will only indicate the "prescription" data - which radio components should be replaced. With some comments.
So, in the VHF-2-2E-03 block, we change:
Capacitors:
it is desirable to replace it with the same type as in the block, but CD is also possible. Possible replacement with a nominal value in the circuits and communication circuits +/-5%, TKE - M47 or blue or gray.
C1, C2 - 10 and 30 pF, respectively. Who will experiment with this capacitive input circuit divider - C2 must be at least three times larger than C1. When setting up the circuit where they stand, turn out the L2 core as much as possible);
C4 - remove (in the original circuits, its value can be different: either 22 or 10 pF). The remaining mounting capacitance and capacitance C6, C7 allows the circuit with the L3 coil to operate at a higher frequency;
C6 - 180 pF. With its help, stretching-laying of the range is carried out - the overlap coefficient changes;
C8 - 10 pF. This coupling capacitor affects the gain and input capacitance of the next stage. Therefore, C8 can be increased, within reasonable limits (there are examples of an increase to 22 pF - information seist from the forum).
C16 - 47 (or 30) pF. Recommended by the forum Ripatehnik the turn of the L4 coil is unwound, a ferrite core is screwed into the circuit (there may be no generation at all for the required restructuring without a core). To fit in the range during the adjustment process, it may be necessary to shorten the core, for this you can bite off about 2 mm of its length. Due to the installation of this ferrite core at C16 \u003d 30 pF, C17 may not be needed;
C17 - 8.2 (or remove if C16 = 30 pF);
C19 - 5.6 pF. Initially, in different circuits, the value of this capacitor may be either 8.2 or 13 pF. This capacitor works to “capture the signal” of the station when the AFC is turned on - the smaller the capacitance, the narrower the capture band, because. the connection with the GPA circuit is reduced. This is important for us - on the FM band, the density of stations is higher and it is required that the AFC work correctly ...
Circuit coils:
L3 - screw in a ferrite core 100НН 2.8x14 mm instead of the standard brass one;
L4 - unwind 1 turn from above + screw in the same ferrite core (cores can be taken from the circuits of old, including tube, receivers. You can experiment with the permeability of the core - use 600НН).
Resistors:
R1 - 1k;
R5 - 3k;
R12 - 0. Put a jumper instead. On the wiring diagram from the side of the details, it is often not shown. It is located (not always) just under C6 from the bottom of the circuit board (on the side of the printed conductors). As an option: if you put a jumper, closing R12 together with part of the coil L3, then it will turn out " as if rewinding "1-2 turns from above it. The circuit is built in resonance with a ferrite core, while C6 \u003d 100 pF (data Ripatehnik from the forum).
R9, R11 - 3.9 k each (if they exist at all in the VHF-2-2E block diagram). R9, R11 were absent in the scheme of a specific converted unit VHF-2-2E-03 - the APCG varicap is powered from the T2 base.
Soldering the elements in the VHF unit is best done by removing it from the receiver. This may require the removal of the vernier cable. After soldering the elements when installing the vernier mechanism, use the above diagram (Fig. 3) - it helped me a lot (I posted it on the forum seist from Saint-Petersburg).
Fig.2
It is also necessary to remember (it is better to sketch) the soldering of the conductors to the terminals of the block for subsequent restoration.
At the very beginning, after opening the receiver, check the voltage that is supplied from the stabilizer to the VHF unit (pin 1). You may need to adjust R40 on the main board of the receiver - the voltage is “not adjusted” at the factory, anyway, they say, according to GOST +/- 20% is permissible. It should be slightly less than -4.4 V. This affects the operation of the unit (sensitivity, gain). With this "new, correct" voltage supplying the unit, measure the modes in control points schemes for direct current- after alteration, they may need to be installed ...
When closing the aluminum cover of the block, do not forget to push the control (signal for tuning) conductor into the hole intended for it - it often happens that the converted opened block and the receiver do not work due to the short circuit of this conductor to the case. It is better to do this by putting on (lengthening) a piece of PVC tube on the conductor in advance before assembly.
Thus, in the above embodiment, the brass cores in L3, L4 were removed and ferrite cores were installed. Because of this, the variant differs from others, previously known, only in denominations. With ferrite cores, the sensitivity is higher (data Ripatehnik from the forum). It seems that the circuits with them are more resonant, the signal amplitude is higher, hence the higher amplification of the cascades, both UHF and heterodyne - in mixers, this results in a larger IF signal at the output ...
How to build? By ear, and according to the indicator (with the maximum extended antenna and the maximum deviation of the arrow of the receiver indicator, with a control receiver, better with a central noise ...)
First, they are determined with the highest frequency VHF station in your region. This can be done with a monitoring receiver or with an officially published frequency schedule.
The rotor C7 is brought out slightly less than the maximum position (reserve for the edge of the range) and the core of the L2 circuit is turned out as much as possible. By rotating the L4 core, they are tuned to the selected station according to the maximum undistorted signal of the station (volume) and the deviation of the indicator arrow.
Further, also and according to the same criteria, the circuit with the L3 coil is adjusted. The same manipulations are carried out by receiving the lowest-frequency FM station in your area. The input broadband circuit with L2 is not so critical to tuning. Therefore, the core that is maximally turned out, but firmly held in the coil frame, can be left without rotating ...
The above part of the article mainly used materials posted by the author (
DV ) in their posts on forum . As well as edited materials from the posts of other conference participants:Ripatehnik from Kaliningrad andseist from Saint-Petersburg. Respect to them from the SMR administration.Unfortunately, the profiles on the site do not contain the names of the authors of the posts behind the specified nicknames.
If you notice, in the splash screen photo in the announcement on home page another "Ocean" is shown, in the name of which there is a proud "RP-222". This is one of the first Soviet class 2 radios with a quasi-sensor range switch and fixed settings. For radio amateurs-reworkers, it is interesting in that the FM block contains a complete path consisting of an input circuit (elements L1.1, L1.2, C2, C4, VD2.1); RF amplifier (cascade on transistor VT1); local oscillator (cascade on transistor VT2); mixer (cascade on transistor VT3); preliminary IF on transistors VT4, VT5; electoral system on the Z filter; IF limiting amplifier and FM detector on a 174UR3 microcircuit, circuits for suppressing side settings and silent tuning (cascades on transistors VT6, VT7 and VT8); UZCH cascade on transistor VT9.
As items electronic tuning VD2 varicaps are applied. The restructuring is carried out by changing the tuning voltage applied to them U H from 1.8 ... 2.5V to 4.6 ... 5V. Varicap VD3 works in the AFC system. The block diagram of the VHF radio receiver "Ocean 222-RP" is shown in Fig. 3.
Fig.3
That is, in practice, a radio amateur has a VHF receiver on a separately made board, which can be used either in the receiver or in the tuner as part of a household audio complex. Our task, let me remind you, is to rebuild the VHF-1 radio range to the FM range.
Converting "Ocean RP-222" (and similar "Veras RP-225" - the schemes are identical) to the FM band can be done using the same method that has already been applied in "Ocean-209" and is given in the first part of the article.
To increase the operating frequency, the capacitance of the capacitors C1, C9, C19 included in the circuits should be reduced. Experimentally selecting their value, it turned out that these capacitors can be excluded altogether - for the circuit to work, the mounting capacity is sufficient. To facilitate work, only one end of the capacitors is soldered from the board - the upper one, the capacitors themselves remain in place. Laying in the FM range is carried out by rotating the brass core of the L4 coil (it may need to be replaced with a ferrite one) and increasing the capacitance of the C18 * capacitor to 47-68 pF (for "stretching" the range). The coils of the L1.2 and UHF L2 input circuits are tuned to the maximum signal by rotating their cores.
With the help of such alterations, it will not be possible to cover the entire FM range. Therefore, it is recommended not to turn off the loop capacitors, but to solder the conclusions lower according to the circuit to the cathodes of the varicaps (capacitances C4 and C12 will increase). Thus, the overlap in frequency will increase.
It is good if the FM radio stations of interest are in the blocked area, but, as practice shows, this is not always the case.
There is another method of alteration - according to the magazine "R / L" No. 3 - 2000, p.15. The value of this alteration is that the VHF-1 band is preserved and, thus, another band (FM) appears in the receiver. It is practically impossible to place the frequency band of the two VHF-1 + VHF-2 (FM) bands on one scale.
The conversion technique differs from the one given above in that, along with changing the values of the loop capacitors and inductance available coils, into the local oscillator circuit another one is introduced coil. This must be done due to the fact that the inductance of the circuit and the quality factor of the varicap local oscillator block VHF receiver insufficient for tuning the FM band to a width of 20 MHz.
Of course, by adding another coil to the VHF unit, you can only choose single band option(Fig. 4). In this case, the conversion method is as follows. The input circuit and UHF circuits are redesigned as described above.
The VFO frequency should be lowered so that the receiver tuning on the FM band is carried out on the second harmonic of the VFO. In this case, the tuning range of the local oscillator should be 49 ... 59 MHz, and the second harmonic should be 98 ... 118 MHz, respectively. To do this, in series with the coil of the local oscillator circuit L4, another coil L4´ is introduced. This coil can be taken from any block of VHF transistor receivers, preferably a heterodyne one (the one recommended in the article by A. Zherdev, from the PTK, was not at hand).
Fig. 4 shows a fragment of the circuit with an added L4´ coil, and Fig. 5a shows a photo of the applied coil from the Aelita-102 VHF radio unit (UKV-1-05S).
Fig.4
Fig.5, a Fig. 5, b
On the board of the VHF unit, the coil L4´ is installed next to L4 in place of the resistor R7 and capacitor C19 transferred to the reverse side of the board (from the side of the printed conductors) (Fig. 5, b). To stretch the range, the capacitance of the capacitor C18 * may need to be increased to 68 pF.
For implementation 2-band option apply the scheme shown in Fig.6. You can switch coils (old L4 and new L4´) in two ways: electronic, like A. Zherdev, using KD409A diodes, or using a relay. These options are shown in Figures 6, 7, 8.
As practice has shown, the circuits highlighted in green in the diagram (Fig. 6) can not be used, but simply disconnect the upper terminals C2 and C9 from the circuit, with the cores turned out, the broadband input circuit is enough for two ranges ..
Fig.6
One group of parallel contacts on the board of the VHF S1.2 "BShN" block is carefully separated from the other with a cutter along with sections of foil. In the future, this switch S1.2 will work as a range switch - that is, it will switch either diodes or control the switching on of the relay. The remaining group of contacts is soldered in the switched on BSHN mode (Fig. 8). In the photo, the soldered part of the board with the relay turned out to be poorly readable. Therefore, you should be guided by the installation diagram shown in Fig.6. It shows the version with the relay. Of all the previous ones tested, it turned out to be the most acceptable.
You should strive to select a relay with a minimum operating current - accordingly, the power consumption and heat transfer will be minimal for it, which is important for the thermal stability of the adjacent L4 and L4´. With the specified parameters, frequency drift during long-term operation of the receiver (many hours) is not observed.
Coil L4´is installed in place of R11 and C7. Together with them, as already mentioned above, R7 and C19 were transferred to the other side of the board (from the side of the mounting conductors) (Fig. 8).
The capacitance C7 may be overestimated by the manufacturer (in my case there was a 100 pF capacitor instead of 18, as required by the circuit) - because of this, the local oscillator in the converted circuit may not start in the VHF-1 range ...
The piezo filter Z can be replaced by FP2P-307-10.7-18, the IF bandwidth decreases and the sensitivity increases accordingly.
The method for setting up the converted VHF unit does not differ from that used when setting up Ocean-209. The only thing that is additionally required is to adjust the UHF circuit for maximum gain by rotating the L2 coil core.
V. Kononenko, RA0CCN
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George. FM on Ocean 209
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