[R-390] To swap or not to swap those aging "reddish" rectangularmica caps

[Jordan Arndt]

P.S.

You can dissasemble the variable caps and clean them internally, but it can 
be a rather delicate operation. It's much easier after you've done a few.

I don't have a link right now, but there are illustrated articles on how to 
restore/rebuild those variables...

agn, 73, Jordan VE6ZT


----- Original Message ----- 
From: "jkharvie via R-390" <r-390 at mailman.qth.net>
To: "R-390 Mailing List" <r-390 at mailman.qth.net>
Sent: Thursday, July 04, 2024 1:13 PM
Subject: [R-390] To swap or not to swap those aging "reddish" 
rectangularmica caps


> Guided discovery continues as I make progress on the RF sub chassis.I 
> received C327 replacement for "high Q" 100pf, 1,000 volt mica capacitor to 
> install on the primary output of T207.I received group input that the 
> green mica mold caps provides acceptable operational service with very low 
> failure rates, and the "reddish" color caps are older generation and 
> appear to have a statistically higher failure rate, and should be replaced 
> with new high q mica caps.Two examples in the receiver, (1) with all 
> reddish mica capacitors, and (2) 1 out of 2 reddish capacitors.My course 
> of action is to keep the green, replace the reddish capacitors.
> Or does the group make the case that while the patient out and ready for 
> surgery to replace both capacitors while opportunity is good?
> Thanks in advance to your vast repository of deep informed knowledge as I 
> work my first end to end refurbishment on this magnificent receiver.Happy 
> 4th of July, celebrate independence day.
> John N3JKE
>
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> Sent from AOL on Android


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