[Amps] Blocking capacity identity?

Karl-Arne Markström sm0aom at telia.com
Sun Nov 4 12:47:19 EST 2007


My junkbox also contains such a capacitor.

It comes out of the 5 kW Granger Associates 172-2 MF/HF transmitters which were assembled by KW,
and was used as the plate blocking capacitor between an Eimac P290A pentode final
and the output pi-L network.

The RF current capacity was certainly sufficient to handle the 5 kW output that these transmitters were able to
produce in their happier moments, and they did not break down even when careless tuning produced 7 - 8 kW
key-down at MF frequencies.

73/

Karl-Arne
SM0AOM





----- Original Message ----- 
From: "John E. Cleeve" <g3jvc at jcleeve.idps.co.uk>
To: <amps at contesting.com>
Sent: Sunday, November 04, 2007 1:14 PM
Subject: [Amps] Blocking capacity identity?


> Following the blocking capacitor thread, I wonder if any one can specify the
> RF current capability of a large ceramic disc capacitor that I have. The
> ceramic form colour is light brown, the dimensions are 3 inches in diameter,
> and 0.75 inches thick. The metal disc on either side is 2.25 inches in
> diameter, and silver plated. The fixing is by a 2BA threaded hole at the
> centre of each disc. There is no manufacturers name (but possibly Plessey),
> but there is a cat/part number printed on the edge of the ceramic form,
> which is 110-0551, the capacity is printed as 2000pf + 40-20%, the voltage
> rating is 12kv, another number, 612, is shown adjacent to the voltage
> rating. The original source of this component was KW Electronics in the UK,
> and it was used in their commercial transmitter construction.  I purchased
> the capacitor as a "useful" component many years ago, when they had their
> closing down sale. I would be most grateful for any information that may be
> forthcoming...regards, John. G3JVC.  
> 
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