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Re: [Amps] Plate Impedance, ARRL

To: craxd1@verizon.net, amps@contesting.com
Subject: Re: [Amps] Plate Impedance, ARRL
From: jkearman@att.net (Jim Kearman)
Date: Tue, 11 Apr 2006 21:04:01 +0000
List-post: <mailto:amps@contesting.com>
From: "Will Matney" <craxd1@verizon.net>
> Class AB, K = 1.5

My understanding is that this value of K applies to triodes, where Ep can swing 
nearly to zero. For tetrodes, Ep cannot swing below the screen voltage. IIRC, 
this has the effect of increasing K. 

It's useful to consider the consequences of slight errors in component-value 
selection. Assuming your variable controls (plate tuning and loading) have 
enough range to get a close match, the negative consequence would be a Q 
different from what you calculated. But if you give yourself enough range in 
tuning and loading Cs, you should be able to tune for _best linearity_ (more 
important than best efficiency) and still get enough Q to reduce harmonics 
below FCC requirements. 

If you calculate a range of plate loads by varying K from 1.5 - 1.8, and then 
calculate tank circuit values based on a Q range of 12-15, you should come up 
with tuning and loading cap values that will do the job. 

73,

Jim, KR1S
http://kr1s.kearman.com/
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