Happy holidays to all on the amps reflector. I have an off topic question
about a loop antenna so if it is not appropriate please remove it or respond to
me directly via email. I am asking here because there are so many experienced
and knowledgeable people on this reflector and the info I receive will be very
useful.
My situation: I currently have a full sized 40 meter delta loop @ 30 ft and
it is horizontal to the ground. I use it on 40 thru 10 with good results. The
antenna exhibits a good SWR on 40 and an SWR less than 2.5:1 on 20 thru 10
meters so the internal auto antenna tuner in my Icom solid state amp can handle
the mismatch. What I would like to do is use it on 75 meters but dont have the
room for a full sized 75mtr loop. The loop is to small for 75 and has an very
high SWR, to much for the internal tuner to deal with. So far I have tried
splitting it in the middle, essentially a full sized 75 meter dipole folded
back
on itself. It works ok, but not a stellar performer. It also lost the advantage
of being a quiet receiving antenna, a characteristic loops are known for.
I have a couple ideas that I want to try but figured I would ask before I go
climbing tress out in the cold. The first idea was to add another full turn to
the loop, separated by a few inches. Essentially it would be a 2 turn loop,
totalling about 260 feet, but only taking up the space of a 40 meter loop. The
other idea was to add a large inductor in the middle of the loop. I have a
large, silver plated, flat wound inductor from a broadcast transmitter that
would
do nicely. I also have a vacuum relay that I could use to short it out for 40
thru 10 mtrs.
My main question is will the two turn loop work? If so will it be better than
the inductor?
I realize that I could use a large roller inductor tuner in the shack but
that defeats the purpose of my lazy hams push button station. My solid state
kilowatt is silent and automatic and it is my goal to keep the station totally
push button.
Thanks for any and all advice- It will save me many trips up the tree and
there is snow in the forecast. Why didnt I do this in the summer?!?!?!
73,
Jim W3ATV
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