>> >>If you look at the Heathkit Warrior and Gonset 811A PA, you'll see
>> >>they are neutralized. So is the AL-811H.
>
>> The Warrior and the Gonset were thought to be neutralized. However, they
>> were not and they were not stable. The SB-200 and the SB-220 were not
>> "neutralized" because someone at Heath came to their senses.
>
>The SB-200 was not neutralized because it was only two 572B tubes. ...snip...
The Ameritron AL-1200 uses only one tube. An acquaintenace owns two
Ameritron AL-1200 amplifiers. The older AL-1200 was not neutralized.
The newer one came with Mr. Rauch's alleged "neutralziation" circuit.
This circuit is not found in *Care and Feeding of Power Grid Tubes*.
The acquaintenance telephoned me and ordered a suppressor retrofit kit
for a 3CX1200A7. I asked him which amplifier was having problems. If
you guessed that it was the allegedly "neutralized" version,
congratulations.
I liked Ian White's comment that, due to phase shift, every
negative-feedback [neutralization] circuit (at the fundamental frequency)
becomes a positive-feedback [regeneration] circuit at some higher
frequency. In my experience, I found that such resonances can readily
discovered with a dipmeter. Mr. Rauch's rejects, out-of-hand, all
resonances discovered with dipmeters. In my un-"expert" opinion, Rauch's
explanation does not wash.
Rich---
R. L. Measures, 805-386-3734, AG6K
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