sokol: RP204 (RP 204);

I recently had a SOKOL RP204 in for repair - the oscillator mixer transistor had failed. Not having any Russian devices I ascertained that TR1 was Silicon PNP type & function RF. I fitted a BF423. Radio did not function - voltage readings showed that current through BF423 was too high. I added 10,000 ohms from base to ground to correct the bias. Radio then functioned perfectly. I have added a simplified circuit for this stage of the circuit in .jpg format to assist in servicing this first stage of the radio. Attachments:

• Simplified circuit of Mixer/Oscillator stage (71 KB)

To thank the Author because you find the post helpful or well done.

Hello Colin,

That's very good !  I have ordered a load of Russian Germanium transistors from a collector in Russia so should you ever need an original transistor for a Soviet radio I might be able to help.

Howard.

To thank the Author because you find the post helpful or well done.

Hello Howard,

if you still have the RP-204, could you scan the schematic from the original paper, and upload it to Radiomuseum ?

as I can see it on your picture.

Best Regards.

Didier THOLOMIER

To thank the Author because you find the post helpful or well done.