Even in smaller transmitters, similar metods had to be used.
The very "temperamental" 5 kW PEP Granger 172-2 MF/HF transmitters
had several Morganite 100 ohm resistors placed around the anode cooler of
the P-290A final, with one end grounded.
They damped out VHF parasitic resonances
in both the tube mounting and its connecting leads.
Without them, a VHF power oscillator resulted at certain settings of
the tune and load controls.
----- Original Message -----
From: "Peter Chadwick" <email@example.com>
Sent: Saturday, July 14, 2007 11:00 AM
Subject: Re: [Amps] suppressors
> Carl said:
> >However there are instances, for whatever reason, that a resistive material
> solves the problem.<
> Very definitely. There's a book now out of print called 'Radio Transmitters'
> by Brown of Marconi. He has quite a lot on parasitic suppression in big
> transmitters - and points out that the box can be a VHF resonant cavity
> (we're talking 50 -100kW transmitters or more) and resistive loading by
> having such a thing as an 80 ohm carbon resistor - Globar type, 12 inches
> long, 1 inch diameter - with one end connected to the anode and the otehr in
> free space can privide enough resistive loading to kill a VHF parasitic. Or
> even several of them at various angles.
> Rather out of our legal power levels.......
> Peter G3RZP
> Amps mailing list
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