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Re: Topband: Need for capacitor

To: daraymond@iowatelecom.net, topband@contesting.com
Subject: Re: Topband: Need for capacitor
From: Gary K9GS <garyk9gs@wi.rr.com>
Date: Fri, 28 Dec 2018 16:09:34 -0600
List-post: <mailto:topband@contesting.com>
Hi Dave,
Take a look here:
https://www.alpharfsystems.com/?s=75+pF&submit=Search
They have both the individual caps, now 18 kV, and the 5 capacitor assembly. 
Good luck






73,
Gary K9GS
-------- Original message --------From: daraymond@iowatelecom.net Date: 
12/28/18  3:16 PM  (GMT-06:00) To: topband@contesting.com Subject: Topband: 
Need for capacitor 
Greetings topbanders. . .

While CQing early this morning I began noticing a faint but troubling smell in 
the shack.  It smelled like over heated wiring or electrical components.  It 
continued to get stronger as I realized the odor was coming from the Alpha 99 
amp.  Indeed, a few moments later it tripped out.  I dug into it this afternoon 
and discovered a leaky 75 pF/6 kV cap which is one of five such caps in a 
parallel bank that is pulled in on the band switch to achieve tank resonance 
only on 160m.  I have removed the bad cap making the amp operational once again 
with the air variable tuning cap making up the lost C (and there’s still a 
little C to spare on the air-variable).  After some searching I cannot find a 
75 pF/6 kV cap.  Mouser does not have anything even close in terms of the high 
voltage rating (hopefully I didn’t something).  The closet thing Newark has is 
47 pF which I have ordered.  I’m guessing the 47 pF is probably OK but how 
important is equal current distribution across the five caps?  Maybe I don’t 
need to be concerned about it?  If I really do need the correct 75 pF/6 kV cap 
does anyone have ideas of a source?    Replying privately is fine.   See you 
all in the Stew.        73. . .Dave, W0FLS
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