[Amps] Tune cap at minimum

[Carl]

Manipulating the 15M coil should have little effect on 20M and none that 
will be noticable on the other bands. In all cases the full tuning ranges 
should be fine.

If it is way off then moving a tap is needed. What I dont understand is "I 
was thinking of squeezing or spreading the coil turns on the 21MHz inductor 
closest to the tube"
Do you have more than one 21MHz inductor?

Carl
KM1H


----- Original Message ----- 
From: "Glen Zook" <gzook at yahoo.com>
To: "Dave Hachadorian" <k6ll.dave at gmail.com>; <amps at contesting.com>
Sent: Friday, October 04, 2013 8:40 PM
Subject: Re: [Amps] Tune cap at minimum


To lower the inductance, the turns need to be farther apart. However, that 
will affect the other bands as well. It would be better to move the 15-meter 
tap so that less turns are selected. I would start with 1-turn less.

Glen, K9STH


Website:  http://k9sth.com


________________________________
 From: Dave Hachadorian <k6ll.dave at gmail.com>
To: amps at contesting.com
Sent: Thursday, October 3, 2013 12:17 PM
Subject: [Amps] Tune cap at minimum


I have an amplifier that tunes up on 21 MHz with the tune
capacitor at minimum value.   It acts like the capacitance should
be even lower for max efficiency and output on 21 MHz. All of
the other bands, 10 through 160 are fine. The output network is
a pi-L, and the tubes are a pair of GU-74b's.

I was thinking of squeezing or spreading the coil turns on the 21
MHz inductor closest to the tube, but I can't find the dang
formulas to figure out which way to go.
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