logo elektroda
logo elektroda
X
logo elektroda
Advanced Search
logo elektroda

Interior of an old Polish radio receiver UNITRA Sniezka R-207

p.kaczmarek2 14202 97
ADVERTISEMENT
Treść została przetłumaczona polish » english Zobacz oryginalną wersję tematu
Reply Cool? Ranking DIY | New topic
Notify about new articles
  • #91 20218624
    kris8888
    Level 39  
    szejker89 wrote:
    And using a ferromagnetic core on the power cable would make any sense?
    .
    It doesn't make sense because a sufficient "obstacle" to the HF interference from the mains side is the power transformer.
    This buzzing you are writing about is during reception on the AM bands? If so, there is nothing you can do about it, it will depend on the position of the antenna, the radio and even the feeder cable in relation to the antenna. This is industrial and domestic interference from many modern appliances.
  • ADVERTISEMENT
  • #92 20218882
    szeryf3
    Level 29  
    Koderr wrote:
    szeryf3 wrote:
    has minor problems with strong station reception.
    .
    What is meant by the term "problems with strong station reception"?
    Are stations with a strong signal being poorly received (overdrive),
    or is the signal of the received stations in general "weak"?

    As I wrote the problem is where the radio is located.
    I have a place in the kitchen where the radio picks up nicely, but the spouse is against the radio standing there.
    Besides, I would have to install an external antenna, but again the spouse.
    The radio receives my favourite stations, but when I want to turn up the volume or change the station, I have to stand on a chair to do it, because the radio is on a furniture chimney.
  • ADVERTISEMENT
  • #93 20219489
    NegativeFeedback
    Level 14  
    pawelr98 wrote:
    And why do I like equipment from the USSR ? Because it is different. A different view of technology, different components. It's not as boring as in unitra, that every other radio has the same head and has 1:1 western components.
    And I happen to have a lot of parts from the former USSR so repairing is no problem for me.


    There is no greater technical junk than equipment from the USSR.
  • ADVERTISEMENT
  • #94 20219537
    szejker89
    Level 14  
    glass2 wrote:
    This radio has a light bulb, I suggest disconnecting it for testing. It should help.
    If this is the case, I suggest routing the power supply to the bulb differently.

    Greetings
    .

    Thank you :) The bulb is connected to a different power switch pin and when I press the switch, the radio plays and the bulb turns off. The buzz is then lost. Actually, the power to the bulb runs together with the volume potentiometer cable. Thanks again for the hint :) .
  • ADVERTISEMENT
  • #95 20220419
    szeryf3
    Level 29  
    @glass2 I didn't think the bulb could , "litter".
    I guess I too will take a peek at my radio at my leisure and correct where the bulb feeds into.
  • #96 20220738
    glass2
    Level 12  
    That's right, and I was surprised. Rubens on YT presented it nicely.
    I hope this voice can be useful somehow
  • #97 21345573
    szejker89
    Level 14  
    Hey :) It's been 2 years since I saved the R-207 and everything is fine. The only thing is when a radio station starts to receive a little worse, there is a hum. Now I got a Unitra Sudety, tuned but with a problem such that when it plays quietly, the sound seems to want to fade. I think I'll start by checking the capacitors. However, and this surprised me, there is a 0.47uF capacitor added in the Sudety on the rectifier diodes, on the path side. There is no such capacitor in the Snow R-207. Why? Is it worth adding it? And what type of capacitor is it, polyester? And I also have such a question, is it worth reviewing other capacitors in Unitra equipment that get damaged with age? I've heard something about film capacitors causing problems, and many people overlook them. And something else that surprised me is that in the Snowball all the Elwa electrolytics are in perfect condition. The 1000uF capacitors have an ESR of 0.00ohm!!!

    Printed circuit board with a 0.47uF 100V capacitor soldered on the paths .
  • #98 21345583
    kris8888
    Level 39  
    szejker89 wrote:
    What surprised me, however, is the added 0.47uF capacitor on the rectifier diodes, on the path side, in the Sudeten. There is no such capacitor in the Snow R-207. Why? Is it worth adding it
    .
    Such a capacitor suppresses the high-frequency interference that can be generated by rectifying the current at the diode's p-n junction. It is worth adding it. A simple polyester one for 100V will suffice.
    szejker89 wrote:
    And another thing that surprised me is that in the Snowball all the Elwa electrolytes are in perfect condition. The 1000uF capacitors have an ESR of 0.00ohm!!
    .
    This does not surprise me. The capacitors from Elva, the higher capacitance ones, are usually in very good condition. Unless the radio has sometimes been in very cold or damp conditions, then things can be different.
Reply Cool? Ranking DIY | New topic
Notify about new articles
Report a violation of the law

Topic summary

The discussion centers on the UNITRA Sniezka R-207, a Polish radio receiver from the 1980s/90s, focusing on its interior, tuning, and restoration. The radio features a veneered chipboard case with a plastic front panel marked "Snow Diora," mechanical tuning via a large knob, and a volume potentiometer. Users share experiences rescuing and refurbishing these radios, noting their durability and historical value despite modest sound quality and selectivity. Technical details include the use of air coils (L2, L3, L4) with specific winding turns (e.g., L4 at 3.5 turns with a half tap), and the heterodyne coil requiring careful tuning or rewinding to cover the CCIR band (87.5–108 MHz). The power amplifier often uses UL1481/UL1482 or equivalents like TBA810, with suggestions to replace transistors (e.g., BC211/BC313 with BD139/BD140) and speakers for improved performance. Common issues include a 100 Hz hum caused by power supply grounding design, which can be mitigated by additional grounding wires or disconnecting the incandescent bulb circuit. Electrolytic capacitors, especially from Elwa, generally remain in good condition unless exposed to adverse environments, but some users recommend checking and replacing those with high ESR. Modifications such as adding a 0.47 µF polyester capacitor across rectifier diodes help suppress high-frequency interference. The discussion also covers tuning techniques using frequency indicators, RTL-SDR devices, and voltmeters on the FM demodulator output. Some users caution against invasive tuning that alters original parameters, suggesting band converters for adapting to different frequency standards (OIRT vs. CCIR). The thread includes comparisons with other Polish models (R-208 Sudety, R-206 Snowbird, Taraban series) and mentions stereo decoder modifications using UL1621 ICs. The overall consensus appreciates the radios' simplicity, durability, and cultural significance, despite limitations in audio fidelity and component quality compared to Western equipment of the era.
Summary generated by the language model.
Popular Topics
ADVERTISEMENT