[AMPS] Blown TL922A... What to do?

[Paul Christensen]

> This sort of action smacks of what happened to Walt Maxwell's
> material and his reputation as a result of an approach to the
> ARRL by a famous former Collins Radio amplifier engineer.

That incident was another terrible shame.  I believe the issue presented was
whether a conjugate match exists at the output of a vacuum tube-based
amplifier at a condition of maximum power transfer.  After the Collins
engineer wrote the article in QST, I went back to Walt's book,
"Reflections," in an effort to determine the root of the inconsistency.
Walt placed a caveat in his text which was consistent with the Collins
engineer's opinion on the relationship of the conjugate matching theorem and
tube-based amplifiers.  However, one had to dig to find it.

Two problems as I see it: the man never completely read or absorbed Walt's
material, and secondly, Walt could have presented the material a bit more
clearly but in all fairness to Walt, I believe he was trying to deliver the
concept to an "amateur" audience.  Nevertheless, Walt's thrust with
conjugate matching in his book emphasized the need to cancel reactances in
the *antenna system* (transmission line + antenna) in order to effectuate
maximum power transfer between the source and its load.  Somehow, the notion
of conjugate matching to achieve maximum output power reached back to the
internal mechanics of the amplifier.  For the intent, purpose and level of
understanding Walt was trying to convey to his readers, any reference to the
amplifier mechanics was probably unnecessary.  As a result, Walt's text was
taken out of context and he is no longer an authoritative source in the eyes
of the League's technical staff.

I'd bet a paycheck that if George Grammer was living and back on the
League's staff at the time of either publication, he would have never
allowed these incidents to occur.

-Paul, W9AC



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