Hi,

I have an old Pioneer SX-202 receiver that have an issue with the FM, all stations are duplicated a few khz apart and both signal are mono.
I tried the alignment procedure with no luck.

Anybody know what could cause that kind of behavior ?

Thanks
A.

 

The bandwidth of the input and IF tuning is about 200kHz for low distortion stereo. An ordinary bunch of tuned LC circuits would make a bandwidth that is too narrow then maybe this receiver tunes some LC circuits at -100kHz and tunes other LC circuits at +100kHz but it causes peak sensitivities at these separated frequencies.

 

Do you have the service manual, looking at the circuit diagram, there are two filters F1 and F2 in the FM I.F. section, these could help with removal of adjacent channel noise.

Service manual..
https://elektrotanya.com/pioneer_sx-202.pdf/download.html

 

Yes, those are 2 ceramic filters so I can't do much with them.

Thanks
A.

Do you have the service manual, looking at the circuit diagram, there are two filters F1 and F2 in the FM I.F. section, these could help with removal of adjacent channel noise.

Service manual..
https://elektrotanya.com/pioneer_sx-202.pdf/download.html

 

Sounds like the IF filter section is out of whack.

 

I just tried my car radio. On weak stations it will pick up a noisy signal on two adjacent frequencies, 200 KHz apart. On stronger ones, it only picks them up on one. Weird.

Bob