>> From: Rich Measures <measures@vc.net>
>
>> During a telephone conversation with Mr. Rauch in late-1990, he told me
>> that he had seen plenty of parasitic damage in the 400 SB-220s that he
>> had repaired. Mr. Rauch did not design the SB-220.
>
>Nonsense Rich. You distort everything you hear to support your kit
>sales.
...the profits of which supposedly go to the svelte, gorgeous, 22-year
old secretary who allegedly licks more than Rich's envelopes, on and on.
>I did tell you very clearly that the 220 had a problem with VLF
>parasitics ...snip...
Indeed you did mention this scenario. However, it didn't wash because
there is no VLF resonant circuit in the anode, and the 50uH HV-RFC has
rather low reactance at VLF.. IMO, the VLF issue looks like yet another
rauchian smokescreen.
>> If your amplifier arced mysteriously, it might be interesting to measure
>> the resistance of the VHF parasitic suppressor resistor.
>
>Heat any carbon comp resistor to 150-200 degrees C for years and
>measure it. Carbon composition resistors change value from long term
>temperature exposure, anyone in electronics for a period of time
>should know that much.
>
True enough, Mr. Rauch, however the suppressor resistors that were being
promptly damaged in my amplifier were essentially shorted out by several
inches of #16-gauge copper bus-wire - - and the fatal damage was
happening during operation at 7.25MHz.
>It's pretty darned hot up at the anode connectors. That's why the
>resistors change.
There is a gale of fresh cooling air at that spot in the SB-220. The
changes were typically taking place in less than a minute. .
>It matters not what the heat is from, nor can you
>tell some time later what did it. All you know is it was heat.
Hmmm. So the changing resistance causes the tune capacitor to
intermittently arc over?
. . And on the starboard side, passengers can see part of the site of
ancient Thebes. Its pharaonic remains include the Great Temple of Amen
and a massive structure begun by Amenhotep III. On and on.
... ...
Rich...
R. L. Measures, 805-386-3734, AG6K
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