[R-390] Post to list

[Cecil Acuff]

Jack and List,

        My experience, though limited, with the R-390 and the info I have 
heard from others is that cap replacement is not usually needed nor 
recommended.  The failure rate of the caps in the R-390 is orders of 
magnitude lower than that of the R-390A.  Even the filter caps don't seem to 
fail. (because they're of a different design)  I have tested those filters 
and various electrolytic type caps and found them to be well within specs in 
the last two I have had through the shop...one on the bench now.  I would 
suggest you do a spot check of several that are easy to get to and make your 
judgment from there.  Make sure you check them at their rated voltage.

You will find it very difficult fitting Orange Drops into the places they 
have put the high quality bypass and coupling caps...many in snap in 
stainless steel brackets...

I would be more concerned about out of spec resistors...especially under the 
regulators, rectifiers and in various places in the audio deck.  Beyond that 
they don't require much!

Cecil.....
----- Original Message ----- 
From: "Jack Sullivan" <jsullivan10512000 at yahoo.com>
To: <R-390 at mailman.qth.net>
Sent: Monday, May 02, 2005 6:10 PM
Subject: [R-390] Post to list


> On R-390 (not "A" version), I am about to replace most
> all paper condensors (we now call them capacitors, of
> course), probably with polyprop. orange drops.  I see
> that these types of  condensors in this set are metal
> covered, and look to be of very high quality (military
> spec., I am sure, is reason for that).  Are these
> metal covered, numerous ones are .01, .1, .22, 1. mf,
> really paper caps, as I suspect?  I have replaced a
> gazillion paper caps in civilian radios, but have no
> experience with military radios/electronics, and have
> never seen metal covered ones like this before.
> Anyone know much about the quality of these metal
> covered condensors, how smart it is to replace them,
> etc.?  I will replace, too, any electrolytics that I
> find not testing well (the 50 mf., 50 volt unit will
> be first to replace, as it is shot, for sure, as
> tested), while two 10 mf are in great shape, and I
> will leave them in place.  Best,  Jack
>
> <P>&nbsp;</P>
>
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