P.S. If your vertical has a good set of radials, you will see about 35 Ohm
feedpoint impedance. You may want to wind your own unun using Jerry Sevick’s
cookbook
http://www.introni.it/pdf/Amidon%20-%20Transmission%20Line%20Transformers%20Handbook.pdf
or buy a readymade 35 to 50 Ohm unun from balundesigns.com
The third option is to build a coax transformer per PA0FRI.
Rudy N2WQ
Sent using a tiny keyboard. Please excuse brevity, typos, or inappropriate
autocorrect.
> On Dec 5, 2020, at 8:37 AM, David Aslin G3WGN <david@aslinvc.com> wrote:
> I'm building a contest station and the time has come to make a choice of
> 160m TX antenna. Looking at DXE Thunderbolt I note that the capacity hat
> extends to a significant distance down the vertical section. It's my
> understanding that will shield some of the radiation from the upper part of
> the vertical. Alternatives like a vertical tee would not have this issue.
> Is my understanding correct?
>
> I'm considering a commercial antenna as high strength telescoping antenna
> tubing is unobtanium in UK. My QTH is an exposed windy location so strength
> matters!
> 73, David G3WGN M6O
>
>
>
> Sent from my Galaxy
>
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