On Mar 8, 10:49*pm, K1HL wrote:
My SB-200 works perfectly 80-15 meters. *10 M opened the other day and
I found the SB-200 would not tune. *Within 30 seconds one of the
572B's blew out and the breakers both tripped. *My exciter, when used
without the SB-200, tunes perfectly on 10 - very low SWR, etc. - so
it's not an antenna issue.
It's got me stumped. *Built the linear in 1970 and never had a problem
til this.
Tnx - Harry

Had you ever used the SB-200 on 10 meters before?

For a good length of time, the FCC required that amps fail to operate
on 10M (really 11M was the target of the law but 10M got swept into
it) until a specific (available to "hams only" as if anyone else
should have a linear) mod had been applied. I forget when that law
went into effect but could it have been as far back as 1970?

Anyway when 10M opens up, 100W will generally do wonderfully (just my
two cents :-)!)

Tim.