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[Amps] Grid Bias Supply followup

To: <>, <>
Subject: [Amps] Grid Bias Supply followup
From: "Steve Flood" <>
Reply-to: Steve Flood <>
Date: Sat, 22 Mar 2008 05:25:53 -0600
List-post: <">>
As a followup to my question about the grid bias supply on the G.E. Ham News 
813 amp (and the B&W LPA-1 is nearly the same design):  

The bias supplies for these amps use a 120:120 transformer, half-wave diode 
rectifier, C/RC filter (40uF/500 ohms/40uF) and a 500-ohm, 25-w rheostat load 
for the adjustable bias.  These supplies are said to provide zereo to -100v 
bias.  Yet, the settings for CW and SSB only use -19 volts and -5 volts.  Why 
then, is it necessary to have -100 volts available?  Seems like a much smaller 
supply would suffice.

Thanks, Steve KK7UV
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