The SB-220 is a near optimum design for it's intended power and size.
Trying to obtain higher power seems to run one right into the limits of
other components such as the power supply filter capacitors, variable
capacitor breakdown, and bandswitch breakdown. Adding 160M operation has
been done, but is not easy. The plate and filament
chokes are a bit small for optimum low band operation.
Power output on 10 and 15 meters is down from other bands...any
solutions floating around out there?
It has occurred to me, as an owner of several SB-220's that an
interesting alternative would be to create an optimum designed
high band amplifier (20/17/15/12/10) with 1200 watts output on all
5 bands, and an optimum designed low band amplifier for 160/80/40/30/20
meters, using the SB-220 as the basic chassis.
I've never gotten sufficiently motivated to do this but think the idea is
worth developing. Perhaps someone would like to bring this out as
a kit (are you listening Carl?)
de Tom N4KG
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