I'll start with a quote from a forum on a site recently discovered (accidentally) on the Internet. "Domestic radio engineering of the XX century" :
“Spring has begun, I go to the dacha. 20 km from the city. "Ocean", rebuilt by me, accepts everything as confidently as in the city. I remember taking him with me BEFORE perestroika ("Ocean") and listening to VHF stations, so he did not receive anything in the box, but now he catches everything in the box ... I'm satisfied. "
This statement by a radio amateur from Kaliningrad was preceded by a discussion at forum of the theme “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 FM stations appeared in the 87.5 - 108 MHz range: it is VHF-2 or FM (although the last abbreviation of the words F requency M odulation is not entirely correct, because it translates as "frequency modulation ...")
Cheap imported (more often China-made) receivers do not allow obtaining high-quality sound reproduction (in a word, "soap dishes"), and "old" Russian (Soviet)-made receivers 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 "Ocean-209", "Meridian-206" or "Leningrad-002"), which, of course, gave a gain in the quality of playback ... I'm not talking about reliability and maintainability of our "mastodons" ...
Their time is gone. And it's a pity to throw it away. Especially radio amateurs. And you can convert (rebuild) to amateur bands. Or maybe not for amateur ones. For example, I do not know of analogs from a number of imported receivers that would be able to sound a small summer cottage with the help of a 1-2 watt speaker with acceptable low frequency reproduction. And "Oceans", "Meridians", "VEFs", "Spidols" ... - can. And the harvest of cucumbers is better ...
As an example, I will give a methodology for restructuring the Okeana-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 schemes of different years of release, including the data of the VHF-2-2S (E) unit for receivers manufactured for export ...
The designations of the elements changed in the process of alteration in the VHF unit on all the schematic 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 specific receiver (at the time of purchase). If the passport-scheme has not been preserved, then you can use any other downloaded from the Internet, or from those that are presented on the forum. Many reference books often come across diagrams and descriptions of receivers with a VHF-2-2S unit. At the time of the most massive production of "Okeanov-209" (late 70s - early 80s) Minsk PO "Gorizont" most often completed them with a block UKV-2-2E-03... Figure 1 shows a diagram of this particular block.
Fig. 1
So, without going into theory, I will briefly outline the essence of perestroika.
The task is to get in the receiver FM band(hereinafter, for convenience, we will call the range 87.5 ... 108 MHz just like that - the FM range ...)
Superheterodyne circuit, intermediate frequency 10.7 MHz. There is an amplifier, a detector and an ultrasonic frequency amplifier in the receiver, they do not need to be tuned or rebuilt.
To get an IF for the FM range, you need to rebuild the mixer available in the receiver (in the VHF unit) combined with the VHF on the T2 transistor to the same 10.7 MHz above the frequency of the range (circuit L4, C16, C7). Ie, so that the frequency of the local oscillator was in the range from 98 to 118 MHz. In addition, for the FM band, it is necessary to tune the wideband 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 capacitance in the indicated circuits (it is simple - to replace the capacitors with others, with a different value) and inductance (by rotation, shortening, selection of ferrite or brass cores, or by unwinding the turns of the coil of the circuit - one or two turns, no more).
To increase the operating frequency, which is what 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 (“packing” the stations of your region “on a scale”, changing the capacity of interstage communication, AFC ...). We will not go into such details - whoever wants (or knows) will figure it out himself. For simplicity, I will only indicate the "prescription" data - which radio parts 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 you can also use the CD. Possible replacement with a rating 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 divider of the input circuit - C2 must be at least three times more than C1. When adjusting the contour where they stand, unscrew the L2 core as much as possible);
C4 - remove (in the original circuits, its value may 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 blocking capacitor affects the gain and input capacitance of the next stage. Therefore, C8 can be increased within reasonable limits (there are examples of increasing up to 22 pF - information seist from the forum).
C16 - 47 (or 30) pF. On the recommendation from the forum Ripatehnik a turn of the coil L4 is uncoiled, a ferrite core is screwed into the circuit (there may not be any generation for the required tuning at all). To fit into 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 = 30 pF, C17 may not be necessary;
C17 - 8.2 (or remove if C16 = 30 pF);
C19 - 5.6 pF. Initially, in different circuits, there may be a rating of this capacitor or 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 bandwidth, because communication with the GPA circuit decreases. This is important for us - on the FM band, the density of stations is higher and it is required for the AFC to work correctly ...
Loop coils:
L3 - screw in a ferrite core 100НН 2.8x14 mm instead of the standard brass core;
L4 - unwind 1 turn from the top + screw in the same ferrite core (cores can be taken from the circuits of old receivers, including tube ones. You can experiment with core permeability - use 600NN).
Resistors:
R1 - 1 k;
R5 3 k;
R12 - 0. Put a jumper instead. It is often not shown on the wiring diagram from the side of the details. Located (not always) just under the C6 on the bottom of the circuit board (from the side of the printed conductors). Alternatively: if you put a jumper, closing R12 together with part of the coil L3, you get “ as if rewinding "1-2 turns from above her. The circuit is built in resonance with the ferrite core, while C6 = 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 VHF-2-2E-03 unit being converted - the APCG varicap is powered from the T2 base.
It is better to re-solder the elements in the VHF unit by removing it from the receiver. In this case, it may be necessary to remove the vernier cable. After re-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 (better sketch) the soldering of the conductors to the block terminals 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). It may be necessary 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 at the control points of the DC circuit - after alteration, you may need to install them ...
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 reworked 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 tubing before assembly on the conductor.
Thus, in the above version, the brass cores in L3, L4 are removed and the ferrite cores are supplied. Because of this, the option 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 amplification of the cascades, both UHF and heterodyne - in the mixers, a larger IF signal is obtained from this at the output ...
How to build? By ear, and by the indicator (with the maximally extended antenna and the maximum deviation of the receiver indicator arrow, with a control receiver, better with TsSh ...)
First identified with the highest VHF station in your region. This can be done with a monitor receiver or with an officially published frequency schedule.
The rotor C7 is brought out a little less than the maximum position (margin for the edge of the range) and the core of the L2 contour is turned out as much as possible. By rotating the core L4 tunes to the selected station according to the maximum undistorted signal of the station (volume) and the deviation of the indicator arrow.
Further, also 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 L2 input wideband circuit is not as critical to tuning. Therefore, the core, turned out as much as possible, but firmly holding in the coil frame, can be left without rotating ...
In the above part of the article, materials posted by the author are mainly used (
Dv ) in their posts on forum ... And also edited materials from the posts of other conference participants:Ripatehnik from Kaliningrad andseist from Saint-Petersburg. Respect for them to the administration of the SMR.Unfortunately, the profiles on the site do not contain the names of the authors of the posts behind these nicknames.
If you have noticed, the splash photo in the announcement on the main page shows another "Ocean", in the name of which is the proud "RP-222". This is one of the first Soviet class 2 radios with a quasi-sensor range switch and fixed settings. It is interesting for radio amateurs-converters because 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); heterodyne (cascade on transistor VT2); mixer (cascade on transistor VT3); preliminary UPCH on transistors VT4, VT5; an electoral system on the Z filter; an IF limiter amplifier and an FM detector on a 174UR3 microcircuit, circuits for suppressing side settings and silent settings (cascades on transistors VT6, VT7 and VT8); cascade of ultrasonic frequency converter on transistor VT9.
Varicaps VD2 are used as elements of electronic tuning. The restructuring is carried out by changing the setting voltage U H applied to them in a value from 1.8 ... 2.5V to 4.6 ... 5V. Varicap VD3 works in the AFC system. The diagram of the VHF radio receiver "Ocean 222-RP" is shown in Fig. 3.
Fig. 3
That is, practically at the disposal of the radio amateur there is a VHF receiver on a separately made board, which can be used either in a receiver or in a tuner as part of a household audio complex. Let me remind you, our task is to rebuild the range of the VHF-1 radio receiver to the FM range.
It is possible to remake “Okean RP-222” (and similar “Veras RP-225” - the schemes are identical) to the FM range using the same technique that was already used in “Okean-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 installation 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. Stacking 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 of the 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 disconnect the loop capacitors, but to re-solder the lower terminals according to the scheme to the cathodes of the varicaps (the capacities C4 and C12 will increase). Thus, the frequency overlap will increase.
It is good if the FM radio stations of interest are in the blocked area, but, as practice shows, this is far from always the case.
There is another method of alteration - according to from the magazine "R / L" No. 3 - 2000, p.15. The value of this rework lies in the fact that the VHF-1 band is retained and, thus, another band (FM) appears in the receiver. It is almost impossible to place the frequency band of the two VHF-1 + VHF-2 (FM) bands on the same scale.
The alteration technique differs from that given above, in that, along with changing the ratings of the loop capacitors and inductance available coils, in the local oscillator circuit another coil. This must be done due to the fact that the inductance of the circuit and the Q-factor of the varicap of the local oscillator of the VHF receiver unit is insufficient to reorganize the FM range 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 alteration technique is as follows. The contours of the input circuit and the UHF are redone as described above.
The VFO frequency should be lowered so that the receiver tunes in the FM band at 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. For this, one more coil L4´ is introduced in series with the local oscillator circuit coil L4. This coil can be taken from any block of VHF transistor receivers, preferably a heterodyne one (such as recommended in the article by A. Zherdev, from the PTC, was not at hand).
Fig. 4 shows a fragment of the circuit with the added L4´ coil, and in Fig. 5, a photo of the applied coil from the VHF unit of the radio tape recorder "Aelita-102" (UKV-1-05S).
Fig. 4
Fig. 5, a Fig. 5, b
On the VHF unit board, the L4 'coil 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 C18 * capacitor may need to be increased to 68 pF.
To bring to life 2-band option apply the circuit shown in Fig. 6. There are two ways to switch the coils (old L4 and new L4´): electronically, 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 bandwidth of the input circuit is enough for two ranges ..
Fig. 6
One group of paralleled contacts on the board of the VHF S1.2 "BShN" unit is carefully separated from the other with a cutter together with foil sections. 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 sealed in the ON mode (Fig. 8). In the photo, the soldered part of the board with the relay turned out to be hard to read. Therefore, follow the installation diagram shown in Fig. 6. It shows a variant with a relay. Of all the previous ones tested, it turned out to be the most acceptable.
One should strive to select a relay with a minimum operating current - accordingly, its power consumption and heat transfer will be minimal, which is important for the thermal stability of the adjacent L4 and L4´. With the specified parameters, the frequency drift is not observed during long-term operation of the receiver (many hours).
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 overstated 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 ...
Piezofilter Z can be replaced with FP2P-307-10.7-18, the IF bandwidth decreases and the sensitivity increases accordingly.
The tuning technique of the converted VHF unit does not differ from that used when tuning the Ocean-209. The only thing that is required additionally is to adjust the UHF circuit for maximum gain by rotating the L2 coil core.
V. Kononenko, RA0CCN
To start…
Some time ago I got my hands on a rather shabby, but still sometimes properly working receiver OCEAN 209. Judging by the state, the receiver flew from the table to the floor as much as a highly qualified pilot did.
The thing is, in principle, 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, stop chatting about what is and what is not, let's get down to the analysis.
Analysis ?! - it's fast!
As one pretty good radio technician said: “I disassemble any device with three tools: a screwdriver, a sledgehammer and a crowbar. Only without further 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 4 screws from the back and remove the cover.
Next, we need to unhook the range knob. It rests on two stiletto heels. We unscrew the studs and pull out the handle with a sharp movement. Now we freely remove the wooden case. Only the front side remains.
We remove the control knobs (if they are still there). Unscrew the 4 aluminum ties and the screw, which is the antenna input terminal with the antenna. Next, carefully release 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, turn up the amplifier up to 10 W, improve the backlighting, remake VHF1 to VHF2 and make it a little divine.
Of course, the amplifier later left the original one, but replaced all the variable resistors.
VHF 1 to VHF2
To get started, stock up on literature: magazine "Radio" for 1977, No. 10, page 36. There is a description and diagram of the receiver.
There are 2 VHF bands - VHF1 and VHF2, respectively. Most modern radio stations are on VHF2 (FM) - 88-108 MHz. Rebuilding the 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 in a search engine a query like "VHF on FM in Ocean 209" and as a result, a bunch of information about how to do this will come out. Basically, this is the removal of excess containers, replacing some with other denominations and adjusting the contours by twisting the cores. One of the cores is replaced with a ferrite one (for reference: they are all brass there). The range adjustment is carried out by the L 4 circuit, the sensitivity adjustment by the L 3 circuit, and the input adjustment by the L 1 and L 2 circuits (if I am not mistaken, they are wound on one frame).
VHF block diagram
I strongly advise you to follow this link: Rebuilding the Ocean on FM. There is a complete and accurate description of actions on the VHF unit.
And further. When I was disassembling and reworking the VHF unit, I noticed that the structural unit may differ from what is drawn in the diagram.
By the way, while you haven't figured out anything yet, I want to give advice: the tuning system for a certain radio station is old (that is, with threads). So that later there will be no problems - it is better to fix it on the rollers with adhesive tape or adhesive tape.
And he is alive and glows ...
The backlight can be made with LED. It is brighter and consumes less, but do not overdo it - the excessive load on the transformer did not bring anyone to good.
A positive voltage is applied to the common wire (chassis). Be careful.
Sounds of radio waves
I did not change the acoustics. I changed the old variable resistors for new ones - this will increase the service life of the radio receiver (in short, I will not look there soon).
Now the speaker of the device. We remove and carefully examine it. If the speaker cone is torn, it is advisable to replace it with a new one - any suitable in size, with a power of 1-2 W, with a resistance of 8 ohms. It can be supplied with a resistance of 4 ohms, but perhaps the output stages will warm up in a terrible way, which over time can lead to the failure of the transistors of the output stage.
I was not lucky. The previous owners of the receiver managed to turn the speaker off. 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 build on such microcircuits that have inverted input and output (for example: TEA 2025 b, TDA 2822, etc.) and the power supply does not exceed 9 V.
Do not forget! The common wire has a polarity not minus, but vice versa! Make no mistake when designing!
Appearance is the most interesting thing.
The most interesting thing is, as always, at the end. (Oh, and the article will be over 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 all dirt, restored the front grill (the speaker suffered from the fork in the process), screwed all the control knobs into place.
By the way, about the pens. A fairly large assortment of control knobs is sold in radio component stores, so this shouldn't 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 just directs where necessary. If you still have problems - write to your profile or leave comments here on the site.
And for the repair of the stylish Soviet Hi-Fi amplifier "Radio Engineering U-101 stereo"!
The video shows the state of the receiver, its appearance, performance. also shown a modified VHF block diagram for the transition to FM waves.Changeover to FM for everyone from Andrey Rostovsky. Ocean 209, scheme
Ocean 209 FM tuning
This video shows the algorithm for restructuring the VHF unit of the Ocean 209 radio receiver to the modern FM range 94-108 MHz Translation of the Soviet Ocean-209 receiver from VHF to FM "Meridian 246" radio review. transfer from VHF to FM
The video shows a method of converting the Meridian 246 radio receiver to FM frequencies. See also a small overview of the receiver. Ocean - 209, FM conversion.
Rebuilt the Soviet VHF band to FM. I did not touch the coil. Capacitors and resistors only. Reconstruction of the UKV-1-05S unit. Secrets of the Old Radio Mechanic.
Instead of a generator - a Chinese transmitter !!! The process of restructuring the VHF-1-05S unit to FM 88-108 MHz is shown in full.
With the participation of the dog Jack !!!
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George. FM on the Ocean 209. Information for the "constriction" of the VHF unit
Factory VHF unit of export Ocean 209 at 88-108 MHz, part 1
First video. To be continued. The Ocean-209 radio is in perfect condition, rebuilt by me on FM.
Sold. Ocean209 alteration of VHF to FM
The simplest FM conversion without equipment at home Radio receiver Ocean-209. Review and repair
The Ocean-209 radio receiver stopped catching radio stations. A cursory examination revealed that the antenna was to blame. How to fix this small malfunction, as well as an overview of the radio, see this video.
And also do not forget about the VK group:
Ocean-209 rebuilt to FM
Ocean-209 rebuilt to FM. Perfect condition.SOLD!
Is there life on short waves? Ocean-209 receiver overview
Ocean 209 - Setting the LF Input. We do it together with Zhora Minsky.
15 minutes - Introduction ... can rewind))) In this video, I show how I make the LF input in the Ocean 209 receiver. it can also be installed in any other receiver. We talk a lot about electronics ...HERE is a technique for restructuring VHF blocks to the FM range.
Ocean 209. 214-216, Ocean 222. Veras 225. VHF units in Leningrad 006. Riga 104, A little on tube receivers. Factory instructions for setting 209 and 214. The total information is about 2GB. The technique is paid.
Who doesn't like my videos - to the garden!
Fight, cats, dogs, ass and no accidents!
HOUSE 2 on another channel.
Ocean-209 radio, rebuilt to FM
Factory VHF unit of export Ocean 209 at 88-108 MHz, part 2
In this video, I check the values of the resistors and capacitors. I forgot to show the capacitor C4 separately in the video. In the Selenovsky VHF block, in fact, there is a permanent ceramic tubular 10 pF. In the shown oceanic one, it is also the same, but with a face value of 22 pf.Rebuilding VHF to FM. Ocean 209. Help for buyers of my method.
A small fragment from the Video, on the restructuring of Ocean 209 (Ocean 214-216) from VHF to FM - as a help - for those who do not succeed, I show the problems that arise, how to solve them, I share my experience.The main video (long) at the link is intended for buyers My methodology for rebuilding VHF blocks on FM, radio receivers such as Ocean 209, Ocean 214-216, Riga 104, Leningrad 006, Veras 222, Ocean 225, and others in which there are similar VHF blocks ...
Video about what is included in this technique Watch HERE
Ocean 209 Tuning to FM ... About My Method, about battery power ...
Paid methodology - mail [email protected]here about My method of tuning to FM ..... in 25 minutes !!! showing the next ocean 209, with a yellow scale, the receiver is still in operation, talking a little ... about the battery power system ... a little about electronics ...
