"Roger Basford" wrote in message
...
I'd say, that as it was working fine on the lower bands, there is a
good chance that the neutralisation wasn't set right for Ten and the
amplifier went into self-oscillation, destroying one of the 572s.

Roger/G3VKM

Being a cathode driven amplifier, Heath did not use neutralization in the
SB-200. My best bet is a bad switch.

73, Barry WA4VZQ