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[AMPS] AB1 and output tank Q?

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Subject: [AMPS] AB1 and output tank Q?
From: (Rich Measures)
Date: Wed, 11 Mar 98 09:50:37 -0800
>Stupid Question (my personal specialty):
>If I'm running an AB1 class amp (e.g., 4CX1000A), it seems obvious that you
>don't *need* a tuned input stage with a minimum Q of 2 (to quote Eimac).
They recommend a bit higher Q, however, 2 will do.  
>But...isn't the same true in the output?  
-   For one thing, to meet the fcc spurious emission spec. you need a 
tank with a minimum Q of c. 10. 
>I'm not sure you could wind a
>broadband transformer at those impedance/voltage levels, but even with the
>proverbial ol' pi-network it seems you should be able to get away with some
>pretty low Q's, and make your component life easier (at least to the extent
>that the output capacitance of the tube lets you).
>Or am I missing something obvious?
-  The Z transformation ability of a tank is determined by it's Q.  Not 
enough Q means no tune.  I would not try to go with a Q of less than 9 
with a low RL tube (high I, low V).  
-  cheers, Scott


R. L. Measures, 805-386-3734, AG6K   

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