I have a HB 2-element 20 meter beam that I have used for years. Had to
play with the element length a bit to get it on frequency, but it works
very well. Better than the TH-3 that it replaced that changed SWR every
time it rained.
I have mine spaced at 1/4 wave with a reflector. Never modeled it or
anything, just put it up, tuned it and use it. 73
Tom W7WHY
On Sun, Oct 24, 2021 at 5:45 PM N4IJ <dougn4ij@gmail.com> wrote:
> I have a friend that wanted a small yagi for 10m and wanted direct feed
> with no beta or gamma feed for simplicity.
>
> I found some old Hygain element to boom clamps I had as surplus.
> To make a long story short, I didn't have any of the Hygain insulators so I
> tried, as an experiment, just a rubber sleeve, about 1/8 inch thick to
> insulate the driven element from the clamp. In testing, the resonance was
> way to high (200khz) from basic modeling I did, and impedance was more than
> 100 ohms. Modeling showed should be close to 50 ohms.
>
> Question is, do you think I introduced series capacitance to the dipole,
> raising the freq? This is all I could think of, since the Hygain insulators
> have a fairly thick spacing between the element and the clamp.
>
> 73 Doug N4IJ
>
>
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