[AMRadio] Re: B&W 5100B Audio Mods

ne1s ne1s at neandertech.com
Wed Oct 20 12:56:22 EDT 2004

i am not familiar with the 5100B, but I would be VERY surprised if the 
screens weren't modulated as well as the plates - it is absolutely necessary 
to achieve 100% modulation of tetrode, pentode, or beam-power calss C RF 
stages. This is usually done with this class of transmitters (~100W 
commercially-manufactured ham AM rigs)with a screen droping resistor from 
the modulated plate supply. It can also be done with a dropping resistor 
from the unmodulated B+, or an audio choke from a voltage source equal to 
the desired screen voltage; in these cases, the screens self-modulate. 


Tom Elmore writes: 

>     Does, anyone know of a source for audio mods for the B&W 5100B
> transmitter. I wonder if anyone has tried to modulate the screens in
> addition to the plate of the finals. It appears the screens use a different
> power supply than the plates of the finals. 
> Thank You
> Tom Elmore KA1NVZ
> Anchorage  Alaska 
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