[Collins] 516F-2's updated

[Gerald]

On Sun, 2005-07-10 at 16:53 -0400, Cam and Juli Hedrick wrote:
> Hi all, 
> First of all I thank you each and every one from the bottom of my heart.  I
> replaced every cap and the selenium diodes today and all was well.  After
> powering up the C1 replacement fried after two minutes into a contact.  I
> promptly pulled it and after testing the factory caps and finding them to be
> in spec. reinstalled them.  I went back on the air and checked into the
> Maritime Service Net and all went well.  The cap used to replace C1 is as
> specified in the service manual, but alas could not take the heat.  I was
> somewhat concerned when I installed the cap due to its small physical size,
> and found that to be well founded.  I imagine that others may have had this
> experience, so what make should I go with to get the results I seek....PSK31
> type duty. 
> I'll stick with the originals for now.
> Thanks,
> Cam
> WA4JKW
> 
Polarity on the electrolytics was critical. In this circuit positive is
grounded.

How did you check the existing caps? They need to be tested for leakage,
capacitance and maybe power factor. When abused from the AC leakage of
the selenium, they will have high leakage and poor power factor and
probably will have a short continued life. And if they blow (though R7
should keep them from blowing), they may fill the chassis with shredded
foil and conductive electrolyte mixed in conductive crepe paper.

I've suggested the Sprague Atoms from Mouser as being appropriate parts,
knowing they sell other parts that are far more compact, but not like
the originals.
-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer