Amps
[Top] [All Lists]

Re: [Amps] low Q output matching

To: amps@contesting.com
Subject: Re: [Amps] low Q output matching
From: Manfred Mornhinweg <manfred@ludens.cl>
Date: Sun, 11 Nov 2012 17:59:26 +0000
List-post: <amps@contesting.com">mailto:amps@contesting.com>
Carel,

Hi, I was wondering what else, besides bad harmonic suppression, will happen
when I design my (single band) output matching network (PI-L)  with low Q
(lowest Q needed to get the match done) ?

I can't really see any problem, except less good harmonic suppression.

But maybe you haven't realized that on the high bands you often have no option but to use high Q, because of the tube's internal capacitance. The lowest Q you can use is dictated not only by the impedance transformation ratio, but also by the sum of the tube output capacitance and the circuit stray capacitances in that area. When you push a tube with rather high capacitance to a relatively high frequency, you can end up forced to use a Q of 20 or 25 or even higher, just to absorb that high tube capacitance!

Manfred

========================
Visit my hobby homepage!
http://ludens.cl
========================
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps

<Prev in Thread] Current Thread [Next in Thread>