Date: Wed, 19 Sep 2018 02:03:09 +0200
From: "Peter Voelpel" <dj7ww@t-online.de>
To: <amps@contesting.com>
Subject: Re: [Amps] PASSIVE NEWORK CATHODE INPUT
<Of course it works on the GS35b and also flawless on Henrys 8K ultra.
<With 3KV on the GS35 anode gain is slightly more then 11dB.
<73
<Peter
### The passive input on the henry 8 k ultra is a dogs breakfast at the best
of times.
The 3CX-3000A7 is already 50 ohms. So what are they trying to match ? You
also
have 38 pf between the grid and the cathode..which is directly in parallel
with the drive.
Put a 38 pf cap across a T connector at the input of a dummy load and see what
happens. ,
esp on the upper 20-10..and also 6m bands.
## They cut one too many corners on the 8 K ultra. The cold sides of the
relays they used
to pad both tune and load would burn up. Blower used is the wrong unit. You
always end up
with some swr on the input of the 8K ultra. Then they tell you not to use
the auto tuner in the xcvr..
as it will try and track..and fails. There are several other issues with the
8 k ultra. The entire B+ supply
is right out of a 1954 hand book.
The suppressor / plate choke setup was another dogs breakfast... that finally
got sorted out on the
very last production units made.
## JA6TAY got the relay switched PI nets down to a fine art on his latest
production runs of his now
available commercially made 3x3 160-10m amp.
## You want some flywheel action with a tuned input..and a passive input
wont provide that.
With any PI tuned input, that 38 pf of grid to cathode C is simply
absorbed into the C2 cap on
the pi tuned input....ditto with any other GG triode.
Later.... Jim VE7RF
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