Thanks for your help Will as well as others,
I am using James Hawkins Pi program. The programs default value for QO
is 12. I know the plate resistance and freq; I just don't know how to
derive at the correct QO value?
Chris
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com]
On Behalf Of Will Matney
Sent: Thursday, January 06, 2005 9:40 AM
To: amps@contesting.com
Subject: [Amps] PLATE RESISTENCE
Chris,
The Q is of the tank circuit and is added in the formula after you find
the plate impedance. You are correct that the impedance will be 1/2 of
one tube. A Q of 10-12 is used for the proper action of the tank circuit
as a filter for harmonics, etc. There's an Excel spreadsheet available
at several websites for determining pi and pi-l tanks. I think Rich
Measures has it on his website. Just input the plate impedance, the Q,
and frequency, it will determine the Tune C, Load C, and L. Then for L,
use the air coil formula in most text books. The coils wire diameter
needs to be sized for the power out and the frequency to hold the Q you
want. This wire size is in a chart in most ARRL and radio engineering
books. You will see that the gage raises with the frequency. 12 to 10
meters and up will use tubing for legal limit output. About 6 meters and
up is where using a coil will stop and striplines are used.
Will Matney
Question,
In a 2 tube design the plate Z ohms are cut in half when in parallel
right? Another words the tube plate Z of 1100 ohms is now 550 ohms
correct? How about QO? I have a QO of 12, what would that be?
Thanks for the help
Chris
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|