[Amps] Plate Impedance, ARRL

[Will Matney]

Jim,

I'm not knocking using 1.8 as that's what I use and it works. The reason I broought all this up is that they do not make it clear from what I read that these factors are for triodes only that I seen. Also, the terms differences that we use where they say the plate load resistance is the same as plate impedance.

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On 4/11/06 at 9:04 PM jkearman at att.net wrote:

>From: "Will Matney" <craxd1 at 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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