[AMRadio] Low modulation Gates BC-1T


SBJohnston at aol.com SBJohnston at aol.com
Sun Feb 25 22:42:56 EST 2007


Deep in the bowels of my junk I found some resistors for a test of the whole 
modulation section of the Gates BC-1T.  I put five large-ish (each like a roll 
of quarters, maybe 50 watts?) 800-ohm wirewounds in series across the 
secondary of the modulation transformer.  Thaty would seem a good load: 4000 ohms.  I 
put an RMS voltmeter across one of the resistors in the stack.

Applied tone to the input... enough drive to produce 200 mA of combined 
modulator current produced about 100 volts across the one resistor.  400 mA got me 
about 200 volts.  And the tube plates were medium-glowing at 0.2 A (what I'd 
consider normal for 833 modulators) and quite brightly glowing (more than I'd 
like to see on an 833) at 0.4 A.

Didn't run it too long, but after I shut it down the resistors were hardly 
warm at all.  

Steve WD8DAS


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