Tom McAlee wrote:
> I wanted to improve that also. I called and spoke with Bob Locher, W9KNI,
> at Butternut. He said the voltage wasn't the only issue and that the N750
> doorknobs would become less stable at higher power because of their
> temperature rating. He suggested not only increasing the voltage, but using
> NPO-rated doorknobs.
>
> I put a few together to come up with the same capacitance but at 30kV with
> NPO doorknobs. After that, I was able to run legal limit with no problems.
>
> Tom, NI1N
The best way to attack the problem is to search hamfest fleamarkets for
those old fashioned bakelight cased mica transmitting caps. I don't
mean the jobs with the solder lugs or those with threaded holes in the
end, I mean the kind with brass screw terminals and nuts. These have a
flange mount base with a hole on either side for a screw. These will
allow you to use the HF-2V at the legal limit without drift (or
explosion as is the case with the originals). I used 'em at J52US and
9L1US with good results. I also replaced the upper section of tubing on
my HF-2V with stouter material so that I could move the top loading
wires up near the very top of the antenna. I used four wires, somewhat
longer than suggested, attached to the antenna by a garden variety hose
clamp. These made the antenna useless on 40m (the resonant point
dropped to about 6.7 MHz, even with all of the coil shorted) but made it
work pretty well on 80 and 160m.
There's always a secret though. In J5, I had the antenna mounted atop a
five storey building. From 9L it was on a three storey building on a
400 foot hill overlooking the Atlantic. There were many, many radials
in use at each location.
The HF-2V is not an ideal antenna for 160m but it'll allow one to work
some DX from a small piece of real estate.
Dave Heil K8MN
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