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[AMPS] Blown TL922A... What to do?

To: <amps@contesting.com>
Subject: [AMPS] Blown TL922A... What to do?
From: 2@vc.net (measures)
Date: Tue, 5 Sep 2000 20:08:01 -0700
>
>> Ä  One of the debators tested the 922's cooling ability, and one debator
>> probably only pontificated about it.  //  The Grate Parasitic Debate is no
>> longer controversial.  The missing piece of the parasitic puzzle was how
>> does the VHF potential from the anode get stepped up to roughly double the
>> anode supply voltage, thereby resulting in bandswitch and/or  Tune-C
>> arcing?.  The answer is that when there is a VHF series-resonance in the
>> Tune-C at a frequency Near the parasite, the Tune-C acts as a Z-step-up
>> L-network instead of a low-Z path to gnd.  The person who made this
>> important discovery is Mr. Rauch.  Congrats, Tom.  Unfortunately, he is
>> seeming too embarrassed to discuss it with any of us in public.  
>
>Rich, you are amazing!
>
>The series resonance actually makes the input impedance of the 
>tank look like only a few ohms!
>
This is true only when the series resonance is not offset from the 
parasitic freq.  L-networks are never resonant.  When the resonance is 
Near but not dead-on the parasitic freq., the L-network effect comes into 
play and the potential is substantially increased.  

>It actually makes it impossible for the tube to drive significant 
>voltage at the tank at VHF! 
>
?  You seem to have missed the word "Near", Tom.  

>Thanks goodness for that, because if the tuning capacitor did allow 
>significant VHF or UHF voltage the amp would be a TVI nightmare.
>
?  Which TV station is on 120MHz? 

>Nice try though! A for effort!
>
?   "A" for Avoidance of reality.   
>
later, Tom. 

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


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