Thanks for the input Ron. The open-wire fed antenna has really captured
my interest. I have not had any luck get the 90' antenna to load on
80/75 meters. My balun us switchable between 1:1 and 1:4. I just
switched it to 1:1 after reading about baluns on the DX Engineering
website. Perhaps that will make the difference. I have plenty of room
so the 135' of wire is no problem. I could also go much larger - 260'
or more. Just trying to weigh practicality with performance.
Considering how well it is working so far, I may drop the collection of
trap dipoles in favor of a single open-wire feed system.
Doug -- K0DXV
Ron D'Eau Claire wrote:
> -----Original Message-----
>
> I was looking for the specs for the KAT3 tuner option for the K3. Just
> wondering what the tuning range is and if it will fully replace the LDG
> AT-200 I'm currently using. After years of coax fed dipoles I finally
> got around to experimenting with open wire fed dipoles. I'm quite
> impressed with the results. I'm currently using about 90' of wire fed
> dead-center with 450 ladder-line into a 1:1 current balun. The LDG
> AT-200 seems to tune it just fine on everything from 40 to 10. The next
> one will be 135'. Hoping the KAT3 will handle it so I can have one less
> piece of equipment on the desk.
>
> Doug -- K0DXV
> Clark, CO
>
> -------------------------
>
> I don't know the LDG so I can't answer your question about the matching
> range but I can say that your 90 foot wire will work as well as a 130 foot
> wire on 80 meters. Crunching a few numbers, the "loss" caused by the
> shortening is less than 0.2 dB. Indeed, you'll find virtually no additional
> penalty operating it on 160 meters at that length.
>
> If the tuner won't handle some frequencies, adjust the length of your
> antenna (or feed line if that is easier). You should be able to find a
> length that the tuner can match on all the bands without significant
> penalty, at least on 3.5 MHz or higher.
>
> The impedance gets quite low when the antenna gets down near 1/4 wavelength
> or less and might exceed the KAT3's range. Assuming a height of 40 feet, the
> impedance at the center of a 90 foot wire at 3.5 MHz is about 13-j600 ohms
> while at 1.8 MHz it drops down to only about 0.6-j1800 ohms. The feeder will
> tend to raise that impedance, assuming it isn't more than 1/4 wavelength
> long.
>
> Ron AC7AC
>
>
>
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