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[Amps] 8877 Input network testing

To: amps@contesting.com
Subject: [Amps] 8877 Input network testing
From: jeff millar <wa1hco@adelphia.net>
Date: Thu, 15 Jul 2004 21:54:14 -0400
List-post: <mailto:amps@contesting.com>
I'm restoring an 8877 on 2M and it needs a better match on the input network. I've designed several input network options and now need to test them. Here's some questions that I hope someone can answer...

* According to the data sheet, an 8877 has a Zin of 54 Ohms and 34
pF in parallel. For testing, I've soldered a 51 Ohm resistor from
cathode to ground (close enough), drive a bit of power and tune
for minimum reflected . Does this work? Can I expect the input
capacitance to remain the same even with the tube off?
* How much additional stray capacitance comes from the tube socket? The matching network isn't working as expected and I'm not sure why.


thanks in advance...

jeff, wa1hco
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