[Lowfer] L.F. LOOPS

[Chris Trask]

Rick,

>
> Hi all,
> I was just looking for opinions on feedlines for small loop antennas.I
built a
> 3 ft square loop with about 24 turns .I plan to to tune it from  about
160 -500
> khz. It wil be placed outdoors.I havent decided how to feed it yet.Should
I link
> couple or direct couple it?Should I coax feed it or use twisted pair.? I
have
> some nice 22 ga. shielded twisted pair.
> I will also be remote tuning it using varicaps.
> Any input would be greatly appreciated.I have read too many loop articles
recently
> only to become more confused!
>

    Funny you should bring this up as I'm going to put a paper about
varactor tuned loops for HF on my webpage soon, maybe as early as tomorrow
if everything goes well.  I'll post a message on this group when I do.  Even
though it's oriented towards HF receiving loops, you may find information in
it that will be useful for what you're doing.

    I found that coupling to the loop balanced, operating the varactors
balanced, and keeping the impedance stepping balanced until the very last
stage before going to coaxial cable does wonders for reducing harmonics and
intermodulation problems with AM BCB stations.  The transformer construction
is a critical item for good performance, and I used a combination of
powdered iron toroids and ferrite balun cores to get good results and keep
the cost down.

Chris

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