>> >Rich, the problem with getting old and having a number of amplifiers is
that
>> >I sometimes forget what I have. My wife claims I have too much stuff.
But
>> >your comment reminded me that I do have a Collins 30S-1 amplifier. It does
>> >not have parasitic suppressors.
>>
>
>
>I do not have all of the editions, but it was after the fifteenth edition of
>Bill Orr's
>Handbook that parasitic suppressors started appearing on ceramic tube amp
>projects therein. There are even projects in the fifteenth edition that
>have no
>suppressors on 4-250A/4-400A tubes. Somewhere between the sixteenth and
>twentieth editions did suppressors appear on all amp project articles. This
>includes a few 8877 articles that had no suppression devices.
>
>My guess is that things became progressively squirrelly as we added 160m and
>WARC bands,
** adding new bands or adding 160m has no effect on a HF amp's vhf anode
resonance and on its vhf gain.
>and especially as anode voltages increased above 2500-2700 volts
>to 4000 volts on the 8877 and other tubes.
** More anode V undoubtedly means more gain.
>Also, the "miniaturization" of amps
>from large racks to bread-box size played a part in this.
** More compact layouts would seemingly tend to move the anode's
resonance up since the lead length between the anode and the Tune-C would
probably be shorter. I'm not sure what the effect would be on vhf
stability.
>
cheers, Phil_
- R. L. Measures, a.k.a. Rich..., 805.386.3734, AG6K,
www.vcnet.com/measures.
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