[AMPS] Suppressors, measurements, and acrimonious blather
Thu, 3 Aug 2000 17:07:27 -0500
> In commercial industry, the topic simply does not come up. If your
> measurements demonstrate that you need a suppressor, you use one. Why it
> occupies so much email bandwidth in this circle is really quite a puzzle to
Unfortunately, the average casual amp home-brewer has nowhere near the
test equipment necessary to determine the need for a suppressor in his
particular lay-out. He is constantly in search of a device that works like a
low-pass filter, perventing all VHF oscillations from 30 mhz up.
Many got on the "nichrome bandwagon" hoping that a 'cure-all"
had been found. Most of us have personally witnessed or have first
hand knowledge of successful "nicro-exorcisims" in unruly amps.
Many of us have been led down the rosey path of duplicating designs
described in construction articles and found in handbook projects.
Unfortunately, these designs were duplicated from looking into an
old Collins or Johnson radio and "counting the turns" rather than testing
and producing a device unique to the lay-out presented in the article.
We have all assumed that duplicating a suppressor in a Collins 30L1
should be good for any project using 811A's or 572B's. We have assumed
that looking into an Alpha 77; measuring the strap and reading the color
code on the resistors will be good for any 8877 project. Fortunately, the
pendulum is swinging in our favor, as the newer generation of tubes are
much more forgiving and easier to deal with.
Carbon resistors were used in many places that they shouldn't have been
in amps because they were cheap, almost non-inductive, and commonly
available. Like their sisters, the paper capacitors, the wheel has turned,
and it is time; it is time for them to go!
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