Re: Center-fed antennas
Posted by
Wes Stewart-2 on
Oct 11, 2019; 12:32pm
URL: http://elecraft.85.s1.nabble.com/KX2-Antenna-Curiosity-tp7655612p7655656.html
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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