Hi Mike,
Highest output
is still obtained with the Load control on 10.
Most amplifiers do not have enough capacitance in their variable loading
capacitor to operate much lower than on about 14 MHz. Fixed capacitors
are switched in parallel for the lower bands. An air variable of high
enough capacity to work on 160 or 80 meters, without paralleling some
fixed capacitors, would be huge, and the amplifier cabinet would have to
be much larger to accomodate it. My guess is that in your amplifier one
of the fixed capacitors that should be paralleled with the variable
loading capacitor has failed, become disconnected, or changed value, so
that when you're on 80 meters, your pi-net really does not have enough
loading capacitance. Could be a burned contact in the band switch or a
loose screw terminal on a doorknob capacitor.
Disconnect all power and short the HV to ground before checking it out.
DE N6KB
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