I would say something slightly different. Firstly I am assuming the PA is on.
It might help to measure the input, especially if it is a valve amplifier.
If it is solid state the input match is more likely to be RF power
dependent, but if the match is really bad at low power it is not likely to
Thanks to all who have replied.
The amplifier that I have in mind is an old Dentron GLA-1000B that I am
restoring. It is a grounded grid sweep tube amplifier and uses fixed pi
networks (a different network for each band, selected by the band
switch) at the input. It is supposed to have a
Steve,
The KPA100 will tolerate a 2:1 SWR with no problem. That is not
uncommon with solid state amps.
If you do have a HI SWR problem with the input circuit, it would likely
indicate a defective component in the input circuit (most likely a
capacitor).
My GLA1000 is not up and running
Steve,
It sounds like you have a good handle on all of the issues. I have the same
problem with my old Swan 1200X sweep tube amp that I have used with my K2
and with my current K3. This amp has no input matching networks at all! I
also have an old SB200 Heathkit amp that does have input
Fellow Elecrafters:
Is it possible to measure the input impedance of a linear amplifier by
using an antenna analyzer (such as the Pal Star) at the input of the
amplifier in place of the rig?
Would the amplifier input impedance be the same for the very small
signal that the analyzer generates
think it will
tell you anything useful. With power on the amp, it might.
Willis 'Cookie' Cooke
K5EWJ
--- On Mon, 1/26/09, Stephen W. Kercel kerc...@suscom-maine.net wrote:
From: Stephen W. Kercel kerc...@suscom-maine.net
Subject: [Elecraft] Amplifier Input Impedance
To:
Cc: elecraft
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