[AMPS] SB220/SB221

[Rich Measures]

>> 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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