[Collins] Bucking Voltage

[Dr. Gerald N. Johnson, electrical engineer]

With 12 volt filament transformers uncommon, its easier to find a
Buck/Boost transformer made for the task. They come in two sets of
voltages: 12/24 and 16/32 with a dual voltage primary 120/240. For
something like a 3 amp load of a 516F2 and 12 volts drop, you need the
35 or 50 watt size of the 12/24 with primary windings connected in
parallel and secondary winding connected in parallel. Then you want to
put the primary and secondary windings in series so with the primary
excited you get more voltage across the two windings in series. The
boost connection for full primary voltage. But to make the buck/boost
run cooler and more efficiently you want to apply the high line voltage
to the series connected terminals and take off the load voltage from the
primary terminals. That way the buck/boost transformer has the benefit
of the reduced voltage too.

73, Jerry, K0CQ, Technical Advisor to the CRA.
-- 
Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.