[Amps] PASSIVE NEWORK CATHODE INPUT

[Peter Voelpel]

I use only SS transceivers myself as well as other users of amps which I had
my hands on.
The return path for the RF current is closed already via the cable
capacitance between linear and transceiver or IPA.
The shortest cable is 6m long, some are much longer.
However, the input resistances of the tubes used in the amps are all between
40 and 70 ohms.
Most are 3CX3000A7 in modified Henry 3000D decks, others 2-3 QB5/1750 in
parallel.

73
Peter, DJ7WW



-----Original Message-----
From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of Jim Thomson
Sent: Montag, 24. September 2018 11:49
To: amps at contesting.com
Subject: [Amps] PASSIVE NEWORK CATHODE INPUT

Date: Sat, 22 Sep 2018 20:10:49 +0200
From: "Peter Voelpel" <dj7ww at t-online.de>
To: "'Jim Thomson'" <jim.thom at telus.net>, <amps at contesting.com>
Subject: Re: [Amps] PASSIVE NEWORK CATHODE INPUT

<I dont see a reason for it.
<And I make no use of it with my GG amps.
<I dont use a passive input neither with GG amps, only with grid driven
<tetrodes.

<73
<Peter

-----Original Message-----
From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of Jim Thomson


##  You want some flywheel action  with a tuned input..and a passive input
wont provide that. 

............................................................................
......................................


####  Ok, so you dont  use  either  a passive input   nor a  pi  input, nor
a T input. 
I have not had much luck  driving the cathode directly  when using a SS
xcvr. 
Follow the return  rf current  of the GG  triode tube.  Without a PI input,
the
only return is via the braid of the  coax  back to the xcvr, through one of
the caps
in the LP filter, then back down the center conductor of the same coax,
completing
the loop. 

##  I use what works.   I don't have any  tube type  xcvrs anymore. 

Jim  VE7RF
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