[AMPS] 50MHz 8877 amp. plate circuit

[Steve Thompson]

-----Original Message-----
From: Phil Clements <philk5pc@tyler.net>
To: Chris Tran GM3WOJ <gm3woj@talk21.com>; amps@contesting.com
<amps@contesting.com>
Date: 08 May 2000 18:53
Subject: Re: [AMPS] 50MHz 8877 amp. plate circuit


>
>Hi Chris,
>Duplicate the design at http://user.super.net.uk/~equinox/8877.html
>I have used this design several times, and it worked every time.
>The plate choke is very critical here...that may be messing up your
>anode circuit.
>Good luck!
>(((73)))
>Phil, K5PC
I've just got dragged in to trying to fix an amp which is a 'chinese' copy
of the ICD design, and which won't tune nicely. What supply voltage and
power do you run at?

My initial look came up with two points - the Cout of the tube imposes quite
a high network loaded Q and the physically large loading cap used in the one
I'm going to try and fix is probably above self resonance at 50MHz, and
acting as a variable shunt inductor.

When I get it on the bench, I'll report on what the network analyser
indicates.

Chris - if you have the gear, put 2k2 from anode to ground and sweep the
aerial input to see where it's doing the matching.

Thanks,

Steve




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