|[AMRadio] Antenna Tuner Wonderings|
bcarling at cfl.rr.com
Thu Dec 23 05:44:55 EST 2004
DON - you were ROARING IN to Florida on 160m a few months
back. Strongest signal on the band. I had assumed that you were
using a full-sized vertical. Seriously!
I was considering a homebrew "Carolina Windom" for my
On 23 Dec 2004 at 0:03, Donald Chester wrote:
> >What kind of "crappy" antennas are you using, i.e., doublets fed with coax,
> >open wire lines, etc., or end-fed wires? Or, some combination of types
> >Rather that building up a bunch of tuners you might consider putting your
> >efforts into erecting a set of antennas that all worked directly off a 50
> >or 75
> >ohm coax feedlines. Half-wave dipoles, one for each band, for example, or
> >or more of the multi-band arrangements (G5RV, fan and trap dipole, etc.).
> I think the best solution would be to erect one good dipole, as high as you
> can get it, for the lowest frequency band you operate. If you don't have
> that much space, consider a shortened dipole for the lowest band. Feed it
> with open wire line and a balanced tuner (not one of those bogus jobs with
> unbalanced T or L network coupled to the balanced line via a balun). I
> prefer to make my multi-band tuners using plug in coils and split stator air
> variables. You should be able to transform the driving impedance of that
> antenna to 50 ohms nonreactive on about any amateur frequency, without a
> forest of separate dipoles growing out of the shack. Then couple whichever
> transmitter you are using to the tuner.
> At present I use a system a little more complicated. I still use one dipole
> for all bands, but a separate tuner for each band. That way the tuner is
> pre-tuned to frequency and all I have to do is load the appropriate
> transmitter into it and switch the feedline to it.
> The dipole is cut for 80m, but I can load it up on 160 as a quarterwave
> dipole with fairly good results. It is about 110 ft. high, so the height
> somewhat compensates for the shortness of it on 160.
> I use a separate L-network to match the the quarterwave base-insulated
> vertical on 160, which is my main topband antenna.
> 73, Don K4KYV
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