There was a considerable reaction/discussion on this reflector after the
publication last fall in QST of the technical correspondence criticizing
the previous articles by Rich Measures, AG6K, dealing with fixing parasitic
oscillation problems in amplifiers.
I experienced this problem first hand during the cqww cw when one of my
AL-1200s abruptly began spitting and popping and "pegging" the grid current
meter. I franticly called Rich and he gratiously walked me through the mods
(I already had the retrofit materials lying around waiting for an excuse to
be installed!) and we were back up in a couple of hours. I was relieved to
find that the tube was not kaput! This amp was three years old and had never
been a problem in this regard before. I have since installed similar mods in
the other AL-1200 (including removal of the toroidal inductor and other
neutralization circuitry) and it too has been quiet and much smoother tuning.
I obtained the accompanying unpublished rebuttal to the technical
correspondence from AG6K who asked me to diseminate it on the internet.
It is a rather large (20K) file but I am posting it since I received nearly
100 requests for a copy. I have not edited it in any way except to convert
it to a text file.
73 Bill, N6CQ
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