That tube also neeeds 3000-3500V before it shows good efficiency.
My 2M 3CX1000A7 needs 80W for 1800 out at 3000V but it was a pull when I got
it with socket 35 years ago and still runs the same.
Carl
----- Original Message -----
From: "N1BUG" <paul@n1bug.com>
To: "'Amps'" <Amps@contesting.com>
Sent: Monday, May 01, 2017 4:50 PM
Subject: Re: [Amps] 144 MHz GS35B update
There we go. After reviewing pictures of several other amplifiers using
this tube I removed one more turn from the coil on the tube side of the T
match. Input SWR is 1:1 and the amp is making over 600 watts out with 25
watts in. I plan to run it this way for a while before I go for the real
QRO.
Paul
On 05/01/2017 02:40 PM, N1BUG wrote:
I'm seeing more RF output with the new configuration, about 500W for
somewhere around 25W drive. It appears I am going to have some fun
getting the input SWR down but I guess everyone does. That's
probably why there are so many slight variations on coil dimensions
among the various plans.
My first try with both coils having 5 turns 15mm ID, 20mm long
resulted in minimum SWR of 3:1. My second try with 4 turns 15mm ID,
20mm long got it down to about 2.6:1. I am not sure whether to take
another turn off both coils or perhaps just the one on the tube
side. Many pictures of amps I have seen appeared to have less L on
the tube side although I don't see this mentioned in any
accompanying text.
Paul
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