Doug DeMaw had an article on adapting the SB 200 for 160m in Sept. 1979
QST. I utilized the input circuit only per the article to allow operation
on all bands 80 through 10 including the WARC bands. The 15m position works
for 17m and 12m while 30m works when the 40m position is selected. (Before
you comment, it is perfectly legal to use the amp on 30m if the input is
limited to 200W.) The article had a major error which doug confirmed. That
is: the input and output connections of the broadband toroid are reversed
as shown in the article. You'll get a 9:1 input SWR unless you correct it
(reverse the connections to C16 and RL1). Although I haven't tried it, I
have every reason to believe, based on Doug's typically fine work, that the
mod for the plate circuit for 160 shown in the article will work. I've had
the input circuit mod installed for over 18 years with zero problems. Nice
to know that the plate choke isn't resonant in the WARC bands.
73, Steve WB6RSE
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