I just wanted to report that I have been almost successful at converting
my SB-200 with 572B's to 6 meters. I originally wanted to replace the tube
with a GI-7B (and still may do so), but decided that I should give it the
effort to at least try the 572's to "see what happens". I removed several
plates from the tune cap and at the moment, I have a jumper on the output
coil at the 1 turn mark - this coil looks like it "might" be original, but
not sure since this amp was previously modified for ...ahem... 11 meters.
With 30 watts in, I'm seeing ~500 watts out on the bird. Not sure about the
accuracy though because the slug I'm using is for 2-30MHz. I plan on
connecting up the amp to the digital wattmeter tomorrow to see how close I
actually am to the 500 watt mark - it's getting late. I'm also hoping the
signal is clean - I don't have an analyzer. Guess some on-the-air testing is
needed during off-season.
One quick question for you guys who are running modified 6 meter amps -
does the amplifier draw more line current after the mod? I seem to have
allot of output for little input, and when I approach 70 watts in, I run the
risk of tripping the breaker in the house. I'm happy with the 500 watts (if
accurate), but wanted to hear someone else's experience.
Oh, by the way - I didn't touch the suppressors on the anodes. They're
still 3 turns around a 47 Ohm Carbon Comp resistor. I have ~300ma grid
current with ~500ma plate current at 500 watts output.
73's... Larry N1MIW
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