rlm wrote:
>>We could program a server to just dump
>>the archives to the list every six months and you could not tell the
>>difference.
>
>** Not quite. In December, 1996, just before Wes, N7WS, measured
>various parasitic suppressors on the bench with a HP Model 4191A RF
>Impedance Analyzer, the method was hailed as a benchmark by both sides
>of the issue.
So it was. We all believed that Wes's measurements on the suppressors
would answer all the questions.
But during the debate that followed, we found out that it isn't as
simple as we'd believed.
There is no way to evaluate the performance of a suppressor without also
knowing a few things about the amp in which it will be installed: the L
and C of the VHF parasitic resonant circuit (or more practically, C and
the resonant frequency).
Without that extra information about the amp, you cannot work out the
damping resistance that the suppressor will place across the tube, at
the parasitic frequency. In other words, you cannot determine the
effectiveness of a suppressor by making measurements on the suppressor
alone.
> Now that Eric has proposed an encore measurement, Mr. Rauch says it's
>really and truly a bad idea because we need to be looking at "the
>system". However, a Z-analyzer rather obviously can't be used to
>evaluate a system since it evaluates individual lumps of R-C-L, so the
>system arguement appears to be another ploy.
>
The need to know about the "system" - the suppressor *and* the amp in
which it will be used - is not a ploy. It's that thing we learned, the
last time we tried this game.
"Those who cannot remember the past are condemned to repeat it."
-George Santayana, 1863-1953, American philosopher
--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
Editor, 'The VHF/UHF DX Book'
http://www.ifwtech.co.uk/g3sek
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