Topband: Need for capacitor

[Mike Waters]

Thank you, Gary! Now I know where I can buy a spare plate choke bypass
capacitor for my homebrew dual-833C linear amp. :-)

73, Mike
www.w0btu.com

On Fri, Dec 28, 2018 at 4:10 PM Gary K9GS <garyk9gs at wi.rr.com> wrote:

> 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 at iowatelecom.net Date:
> 12/28/18  3:16 PM  (GMT-06:00) 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
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