Rich Measures name has come up, as well as purported comments from Eimac
about his advice. The date of Rich's first article on parasitics was April
1986, in Ham Radio. Notably, it said nothing about nichrome.
The title was "Grounded-Grid Amplifier Parasitics (Simple cure extends
amplifier life).
In the article, Measures mentions that his first writing on the subject was
in "ham notes" in October of 1982. In those notes, he claimed that he
copied the Collins grid suppressor circuit and the amplifier did not
oscillate. In the 1986 article, he claimed he was smarter and found that
using 3 paralleled R-C supressors on the grid of each tube, using 3 x 47-75
pf caps and 3 x 75-100 ohm resistors on the grid of each 3-500 tube
eliminated parasitics. He also recommended a series connected R-C
combination in the cathode, comprised of a .01 cap and 3 x 10 ohm
resistors.
He wrote that when he applied these remedies to a 4-1000 amp that was
unstable at 4,000 volts, the amplifier showed no sign of instability even
when run on 9,000 volts.
At the conclusion, he gave a detailed explanation of why these remedies
solved the parasitic problem.
I can only assume that he discarded these remedies when he came up with his
later remedies, and usually remedies are discarded when they do not work as
well as promoted. It is possible that Eimac made their "alleged" statement
about Rich Measures after these first remedies were applied, and maybe they
were not talking about his later remedies.
73, Colin K7FM
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