[R-390] The OD discussion (Dead Horse Walking)

[Don Reaves]

 Craig said,

> For some reason, the engineers which designed our beloved 
> R-390/A chose not to use ceramic disc caps for bypassing, 
> etc. There has to be a reason why it has such a large ...

I've always wondered if the original designers had Sprague ODs commonly
available to them at the time if they would have specified them in the
receiver.  My hunch is they would have, where appropriate.  

Most of the 40 to 50 year old electronics that get a bit of time on my
workbench have bad caps.  Rarely do I find a bad tube, and most resistors
are only slightly out of tolerance unless they have overheated.  So, Mouser
and the other capacitor vendors are bookmarked for frequent orders. 

I just ordered a few original style Mallory FP twist-lock electrolytics
offered by tubesandmore.com.  These are new, not new old stock, and built
with the original Mallory equipment that tubesandmore purchased.  These
should be drop in replacements for my 75A-4, 75S-3, and 51S-1.  All three of
these receivers have developed moderate hum and I don't want to risk
destroying the power transformers, and they offer a 10% December discount on
orders.  Unfortunately they don't stock a new plug-in type as used in the
R-390A.  

The capacitor thread periodically erupts, and some folks take them way too
seriously.  Remember we need a civil discourse here; there is no need to don
the asbestos suits yet again.  

---
Don Reaves W5OR R-390 list administrator
<mailto:r-390-admin at mailman.qth.net>

R-390 Mailing List Rules:  
1.  Stay on topic, or at least don't stray too far, too long. Things that
are on topic:  R-390 and all the variants (388,389,391,392) and all things
relating to using and repairing and appreciating those receivers.

2.  Be civil - no flame wars tolerated here. 
---