Topband: Need for capacitor

[daraymond at iowatelecom.net]

Wow. . a bunch of excellent responses including Alpha even offering the cap 
bank as an assembly (I understand there may have been some failures of this 
part).  Anyway, I think I got some answers and several good options. 
Thanks for sharing the knowledge.     See you all in the Stew. . .73. . . 
Dave, W0FLS
P.S.  The cap is a ceramic disc.

-----Original Message----- 
From: daraymond at iowatelecom.net
Sent: Friday, December 28, 2018 3:16 PM
To: topband at 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
_________________
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector