[Amps] Tuned input design / measurement questions

[Jim Thomson]

Date: Tue, 16 Apr 2013 19:15:05 +0200
From: "Peter Voelpel" <dj7ww at t-online.de>
To: <amps at contesting.com>
Subject: Re: [Amps] Tuned input design  / measurement questions

The RF cathode current is anode RF current + grid RF current.
The return path imho for it is through the input impedance and chassis
ground, not through the transceiver.

73
Peter

##  draw us a diagram, cuz I still don’t get it.   The explanation below makes more sense and has been
in all the orr books since day 1.   Are u saying all the cathode pulses  ( which is typ triple the dc plate current)
+ peak grid current all some how return to the cathode via the  chassis then up through to the grid, then back to the cathode ? 

##  IMO, it all starts at the cathode and has to end there, its just a loop.   The C2 cap in any  PI tuned input is the return for the
rf cathode current.  Without the tuned input, the only other path is via the braid of coax back to xcvr, then back down the 
center conductor to the cathode..completing the loop, 

Jim  VE7RF 



-----Original Message-----
From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of Vic K2VCO

If you don't have a tuned input circuit in the amplifier, then the return
path for the RF cathode current is through the coax and the transceiver
output tank. This causes the performance to be dependent on the cable
length. It also might damage components in the transceiver.