[Collins] Bucking Voltage

[Dr. Gerald N. Johnson, electrical engineer]

Tony, the variac works, but for how long? As it has a sliding contact
that may need to be rubbed occasionally to keep it clean, it may not be
perfectly reliable as a set and forget. A bucking transformer is more
compact than the variac and there's no way a visitor can crank it up
beyond normal line voltage or way down either way. Though one could
solder a wire to the variac variable surface to solve both problems.

To be really gentle on the radio, it might be nice to start by bringing
up the variac over a period of tens of seconds to apply power gentle.

But the biggest hazard with the variac is the fact that it is adjustable
and unless hidden away may be adjusted by unauthorized visitor. Or the
dog's back or the operator's shin bone.

A multiswitched outlet strip is a fine idea to save on the tender rotary
switches in the radios. A multiswitched outlet strip also works for
keeping computers and TV's quiet when not needed and saves on the power
of instant on circuitry.

A new 10A variac can't be had for $25, their prices have gone up a lot
more rapidly than fixed winding buck/boost transformers made for the
service of changing voltage. Made to be wired as an autotransformer.
Follow my instructions for their most efficient operation. But when
there's 10 volts of 3 amp windings not used in the 516F2 when its
converted to solid state those windings will work too, when wired
correctly as I've already posted in detail.

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