I don't suppose your callsign has anything to do with the success of your
antennas.:-)
Wes N7WS
On 10/10/2019 10:54 PM, Vic Rosenthal wrote:
Things I’ve learned by experience:
In 63 years as a ham, I’ve had several :-) HF antennas. The ones that gave me
the greatest overall satisfaction have been balanced, horizontal antennas. The
worst have been verticals with inadequate radial systems or low random-length
wires. Inverted Vs with angles less than 90 degrees between the wires are not
much good, either.
There is no simpler way to make an efficient multiband antenna than to feed a
dipole of at least 1/2 wavelength at the lowest frequency with open wire line.
With some care in choosing the length of the line, a 1/4 wave dipole can work
almost as well. I’ve worked over 300 countries on CW in the last 5 years on the
bands from 40-10m with a 10m long rotary dipole, in an urban area (it is up 35m
on a building and I run a kW, I admit). I regularly bust pileups on 40m with it.
1:1 baluns work to feed open wire lines, but can become inefficient in some
circumstances and heat up. It’s possible to solve this by compensating for
reactance with a pair of capacitors or inductors before the balun, but a better
solution is a true balanced antenna tuner.
“True Ladder Line” is a good product, but it’s easy to make your own, and you
can use no. 12 (2 mm) wire for lower loss.
Sometimes a 4:1 balun may give a better match, but it will be less efficient
(heat) and do a poorer job of keeping RF out of the shack.
Nothing has worked better for me at cleaning up RF in the shack than an old
Johnson Matchbox, a true balanced tuner.
Victor 4X6GP
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