Noise when tuning in/through signal

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Perhaps the noise is coming from a dirty wiper on the tuning capacitor.  I can't remember how the sections are used on the SX-62 capacitor and whether there is a separate section on the gangs used for the highest range.

There is no AFC circuit in the 62 and the usual discriminator detector defects would also show up after tuning.  But if it is only on FM and not because of the tuning capacitor then I suggest replacing the mica caps in the discriminator can.  I have a SX-42, 3 members of the SX-62 family, and a S-36a and all 5 had leaky mica caps in the discriminator can.

Pete, WA2CWA:
Check the FM IF alignment along with possible FM discriminator component issues.

Edward Cain:
Thanks guys. I'll check the discriminator and do the alignment and see what happens.


Could be any number of things, but one problem I found on a SX-42 was EVERY silver mica capacitor in the IF cans was bad.  You could have one that's intermittently leaking and causing trouble.

Doing an alignment will tell the story.  The alignment should reveal nice, relatively sharp peaks when you're adjusting each xformer.  If you go a couple of turns on the xformer without a definite peak, the caps in the xformer have gone bad (or you have an intermittent coil).

Even experienced pros do not shotgun a recap, especially the 44 in a SX-62. Test after about every 3 replacements to be sure you didnt screw something up.  Of course do the Audio and PS first; its pretty hard to mess those up. Those radios also usually need 12-16 resistors replaced.

What is the FM audio like with no signal or a very weak one?

John, early run SX-42's have not had the SMD in my experience.



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