I've been searching for some hints as to what may be in the resin-encased
amplifier used on the Wellbrook loops without much luck. Their power demand
of 130 mA at 12 volts is kind of high for any FET diff-amp, PNP level shift,
into a balanced to unbalance output transformer arrangement. I'm using that
configuration right now on a tuned loop that only requires 17 mA at 9 volts.
Any ideas or links to useful information?

Thanks,

Chuck, w6pkp