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See Photo above "A"
The major change is an
adjustable coupler
instead of the fixed one in the original. Ten tapped turns per side
provide
simultaneous tap-switching at 2,4, 6, 7 8 and 10 turns on both windings
via a
2-pole /6 position rotary switch.
This allows control over
sensitivity/loudness and some further control over selectivity used
along with
the antenna coupling adjustment.
See Photo above "B"
Other detail
changes include a 165/46 litz
fig-8 wound detector coil, a mini- porcelain insulated terminal post
for the
"hot" side of the detector tank, and remounting the antenna and
detector resonance coils on lo-loss styrofoam pads. All these changes
further
reduce distributed capacitance & leakage losses.
Notes:
12+12 turn
1st
version of the coupler,
tapped every other turn. I subsequently cut off 2 turns of each winding
and
re-ordered the tapswitching as previously outlined. The switch rotors
are
joined & grounded, clockwise switching increases the # of turns
in-circuit
and thus coupling factor.
I've moved the metering jack to
the center
apron of the chassis to make the panel hole location available for the
coupling
unit.
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