[ARC5] replacing C3 and C8 of BC453A

[Kenneth G. Gordon]

On 30 Jan 2015 at 11:56, Mike Feher wrote:

> Right now I do not know where C3 and C8 are, however, I have seen a lot of
> defective mica caps. 73 - Mike/N4FS

C-3, 100 pfd, is the white tubular capacitor on the bottom of the "socket" for 
the antenna coil behind the tuning cap. It couples the tap on the antenna coil 
to the RF amp tube's grid.  

And C-8, 200 pfd, is the white tubular job mounted on the bottom of the 
mixer-tube's socket. It couples the HFO's coil, L-4, to the trimmer capacitor. I 
have never (yet) found either one of those to be bad. (So far.)

Yet. After many years, what takes place in some silvered-mica caps are 
small silver "whiskers" which extend outwards from the silver layer and which 
eventually short-out "plates" internally.

We are finding more and more mica and silver-mica caps going defective.

If Peter has to replace those, using modern silvered mica caps would be 
appropriate.

Ken W7EKB