[Amps] Tune cap at minimum

[Glen Zook]

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.