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[AMPS] Power Handling of Resistors

To: <amps@contesting.com>
Subject: [AMPS] Power Handling of Resistors
From: 2@vc.net (measures)
Date: Wed, 8 Mar 2000 11:04:44 -0700
>
>Hi Dave,
>
>If you can take time out of insulting Jon for a moment, I have a 
>question. 

Jon insulted himself by ignoring the most potentially destructive source. 
 
>
>> What I am saying here is, that if the capacitor bank in a 5KW, 4000 VDC
>> power supply, with 16 or 32 uF of capacitance discharges through an arc
>> (however it is initiated) into a bandswitch or other component, the
>> discharge will take place  so quickly that it will be totally unexpected
>> (unanticipated) with a resultant bang and explosion with accompanying
>> light that all that will be left are crispy critters .  Obviously this is
>> the result of currents and voltages of such magnitude and such  short
>> duration as to vaporize metal.  
>
>Please explain how the energy moves freely from the filter 
>capacitors to the bandswitch, or to any other point in the circuit, 
>without a component failure that occurs BEFORE the big bang.

Since the DC blocking cap is not shorted after the event, we know it can 
not be DC that did the damage to the bandswitch.  My guess is that VHF RF 
does the contact damage because the open 10m position is the one most 
typically damaged.  In the photo of a TL-922 bandswitch on page 33 in the 
October, 1990 *QST*, from left to right, the 10m contact is the most 
heavily burned, the 15m contact is less burned and the 20m contact is 
least burned.  The 40m contact is not burned.  //  So, how does VHF RF 
get past the Tune-C?  The Tune-C is supposed to be a very low Z at VHF.  
.   Tom Rauch expertly  provided the answer when he mentioned that the 
AL-80 has a Tune C resonance that is just above the AL-80's anode 
resonance at c. 155MHz.   This was the missing piece of the puzzle in 
"Parasitics Revisited" in 1990.  Thanks, Tom.  
>
>Can you do that, or is this just blind faith? If it is blind faith, I can 
>accept that as an answer.
>
Methinks the most amazing thing about denial of reality is that it is 
very like being intermittently blind.  

... and to all a good night.  
.

-  Rich..., 805.386.3734, www.vcnet.com/measures.  
end


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