In a message dated 1/13/2007 9:36:33 P.M. Eastern Standard Time,
cgalbrai@umich.edu writes:
I am currently modifying an SB-220 for use on 6 meters by changing the 10
meter section as per the QST article (SB-220 0N 6 METERS) and leaving the
rest of the amp band positions unchanged on HF.
The Sb-220 Plate tune "C" capacity is too high at its minimum point for
operation on 6 meters. You can get it to work, but be prepared to have a
"hairy"
time tuning it up. You have to move the plate tune cap so slowly to find
the "sweet spot" that the motion of your breathing will take it out of
resonance. Also, you'll probably smoke the original parasitic suppressors. I
don't
advise this mod. Using the proper value caps and the right tank circuit, the
Sb-220 makes a great 6 meter amp, but as a retrofit to the original design
its a compromise at best. Been there done that. 73 Lou
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