Has anyone tried shunt feeding by running the shunt wire up the center of
Rohn 45 instead of the more common way on the outside of the tower?
If this would work it would allow me to side mount some beams. I am
presently shunt feeding 80' of Rohn 45 for 160m. My feed point is 15' above
ground. I have 24' of mast sticking out the top of the tower with a 402cd at
104'. This seems to load quite well with a series vacuum variable at the
feedpoint.
By the way, I tried reversing the feed. I grounded the coax shield to the
tower at 15'. I hooked up the center of the coax to the 4 - 1/4 wave
elevated radials. Loaded 1.1:1. Looked good, but turned out to be a great
dummy load. I know some of had success with this method, but not me.
Before I did the shunt feeding of the tower, I dropped a wire from the top
of the tower to the ground with 1' spacing to the tower. Hooked the top of
the wire to the tower and the bottom of the wire to the bottom of the tower.
Made a loop at the bottom. Inserted a grid dip meter. Got a dip at 1.35 MHZ.
When I had an 80m delta loop spaced 8' from the tower, I put a variable
capacitor in series with the wire. I could change the resonance of the delta
loop from cw to phone by adjusting the trimmer in this wire. Figured that
was a lot of interaction with the tower. Delta loop didn't work for beans
either.
Still looking for the magic buttons to make all my antennas play correctly -
hi
Tony
N2TK
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