[R-390] Replacement Capacitors

[Ken Harpur]

I am in favour of replacing all the paper caps...my attitude is 'do it once, do it right'.  After recapping my radio I like the peace of mind from knowing I'll never have to touch those caps again...rather than just replacing the obvious leaky ones only to sit back and wait for the next one to go bad...

I did a full recap of one of my R-390As, I ended up having to replace many of the mica caps too as they were bad. It's made a very noticeable difference in performance although sensitivity on some bands is a lot worse than others...for that I am suspecting the crystal osc deck...

But anyway...I used the 716P caps and I have to say I don't want to use them again...I just don't like the way they look in there. So I have been trying to find an axial Polypropylene Cap. I'll never use metalised film in tube equipment for the reasons that have already been outlined in previous posts.

Sometimes trying to do research in the archives can do your head in...in some cases there is conflicting information or schools of thought (not dissimilar to this cap discussion)...one example is the topic of the Aerovox caps as used in EAC R-390As...some say they are good caps that generally don't go leaky while others say most of them in their EAC receivers were bad. Another one is the infamous cap for the Filters...everyone generally agrees that this should be replaced because it is now deemed unreliable, yet the same type of cap is used in the R-390 (non-A) and it is generally accepted the caps in the 390 were of good quality and don't require replacement.

An idea I thought of recently was to try using either Ceramic or Mica caps as replacements for the bypass Paper caps and Polypropylene for the coupling caps...finding values high enough might be a challenge though...

Regards,
Ken