[R-390] Post to list

[Bob Camp]

Hi

I seem to be the poster child for changing capacitors around here.  
The only parts I have seen with a problem are epoxy coated parts. I  
have not seen problems with the metal jacketed parts or with the  
yellow mylar covered parts. It's easy enough to check one or two  
capacitors for leakage resistance and see if they are in  
specification or not.

A simple test is to put about 50 or 100 volts on the capacitor and  
see how much current it pulls at DC. The specification on most of  
these parts is in the several hundred mega ohm region. A leakage  
current in the sub micro amp region would indicate a capacitor that  
is in specification. Changing out parts that are working ok is not a  
necessary thing.

One thing to be careful of is dirty parts. A part with a bunch of  
crud on it will leak weather it's a capacitor or not.

     Take Care

             Bob Camp
             KB8TQ




On May 2, 2005, at 7:10 PM, Jack Sullivan wrote:

> 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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