Hi Topbanders: I was thinking of reconfiguring my base loading arrangement
on a MFJ-1792 80/40M vertical GP for 160m after reading J. Sevik's article
"Simple Broadband Matching Networks" (1978 Antenna Anthology ARRL). Jerry
used a stack of four T200-2s @ u =10 powdered iron cores, but I see Amidon
has a rather stout T400A-2 that is u = 10. It looks like 24 Turns of soft
3/16 inch copper tubing would fit nicely on such a core to get the 233 ohms
of reactance needed for a 1/8wave vertical match. I can do the fiberglass
tape wrap and put teflon heat shrink over the copper tubing. That would
allow the loading toroid to fit in a sealed NEMA box with a vac variable
and unun feed, which is MUCH more compact than a large airwound tubing coil
that is setting on the bench and would have to be mounted outside the NEMA
box. Question is how well that T400A-2 would handle the KW power level,
as my prior B&W coil stock was heating up and melting the styrene binding
strip material. Is this a practical approach or am I unwittingly putting an
induction oven at the antenna feed?
Mike WA3TTS
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