[Amps] 2m W6PO input T network tuning.

[Peter Voelpel]

Hi Hugh.

In to what impedance did you terminate the T-network when you did the test
with the analyser?
The cathode impedance of a triode in GG, your 8877, is depending on drive
and grid current.
So if you did not use a resistor as a load the cathode impedance is much
higher without being driven

73
Peter
 

-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
Behalf Of Hugh Duff

I'm trying to get the L-C-L  "T network" input circuit of my newly built
W6PO 2m amp to look like 50 ohms at 144 MHz.
The network consists of two series inductors with a variable shunt capacitor
in the middle to ground. The 8877 tube is installed and the input circuit
was constructed per the article. Using my MFJ-259B analyzer I find that the
circuit looks best like 50 ohms with low SWR at
108 MHz.