Why not be interested? It is an interesting project.
I built the active antenna two years ago, not for use with VLF but as an
antenna to use with old broadcast AM radio receivers. I had found that my
old Philco, which was designed to use a random wire antenna, picked up more
hum than than anything else and I needed to place an effective antenna well
above the electric fields existing in my living room and then bring the
signal down to the radio through coax where I could then use a conventional
step up transformer to match the antenna input of the receiver. There are
probably easier ways to make the old Philco perform but I was interested in
the concept of using a short whip, remote amplifier, and coax to suck
signals out of the air. Anyway, it worked well. I found that it was
effective up to about 7 MHz although performance fell off gradually about 4
MHz.
The special power transformer (wound with very low capacitance between
primary and secondary) may be a cost issue. I made my own by stripping the
secondary off a cheap RS transformer and adding a new secondary with a *lot*
of insulation between the two windings to reduce the capacitance to very
near that reported in the qst article for the purchased version of the
transformer.
Don K7FJ
Well after all of the variations of URLs and browsers, I finally clicked
on the Active LF Antenna article and was told "You are forbidden access to
this page....I guess I'm not interested after all :-( ....K4TO
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