[Philcofan]

I just bought one of these and awaiting it's arrival. I see on the schematic #17 and #20 are a 1650uf and a 3500 uf semi fixed condensers. What are these and do I need to replace them? Also is it good practice to change the mica condensers also or let them be?

thanks
Chris

[TA Forbes]

Not sure what you mean by "semi-fixed condenser."

The mica condensers are usually ok, and do not need replacing.

[Philcofan]

I have never seen that either but that it what it says on the schematic. Was unsure if it just another mica one or not.

[morzh]

They are NOT uF. They are pF (uuF). Big difference.

I would measure them just im case, usually they stayut.

[codefox1]

Take a nice clear shot of the RF section when you get the set. These appear to be trimmers, but are not mentioned in the alignment instructions on the ARF scan of the Riders on this set. Agree, probably OK. I'd leave them be until after the restoration is done and see if alignment goes well.

You can get a much better schematic and notes set from Chuck's site
http://www.philcorepairbench.com/schematics.htm

[Radioroslyn]

As I look at the diagram it looks like the 1650mmfd cap defiantly will have an effect on the osc fq. The 3500mmfd seem like a pretty large value considering the fq, I'm thinking it's a bypass.
Terry

[Ron Ramirez]

Codefox nailed it. They have the appearance and construction of trimmer condensers (capacitors), but they are not meant to be adjusted. They were adjusted to a certain value in pF at the factory and were meant to be left alone from then on.

[Philcofan]

Great thanks guys. Still waiting for radio to be shipped. hope it arrives in one piece!

Chris