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Early
notes on the Pennant
By Earl Cunningham, K6SE
Flag and Pennant mail list, November
3, 2000
When I initially tested the computer model Pennant design in the
real world (and after detuning my 160 and 80-meter verticals), the
F/B tested on-the-air with a local ham about 5 miles away almost
exactly as it did in the computer, about 35 to 45 dB F/b.
The coax came straight down to the ground from the feedpoint of
the Pennant and then along the ground to the shack at right angles
to the Pennant. There were some ferrite beads on the coax at the
feedpoint end, but probably not enough to make much difference.
The transformer was in a rectangular refrigerator plastic
box measuring about 2" wide by 4" long by 2" deep.
The point of the Pennant was attached to two terminals (screw studs)
coming out of the sides of the box and the coax and the SO-239 coax
connector came out of one end of the box.
The box was mounted vertically on the wooden post supporting the
point of the Pennant 13 feet above ground, with the coax connector
facing downward.
(Actually, there were two Pennants installed point-to-point with
a DPDT relay in the box to switch the hi-Z winding from one Pennant
to the other to facilitate F/B measurements. The control cable for
the relay routed the same way as the coax.)
Although it is good practice to run the coax horizontally
away form the antenna in the plane of the antenna, this can't always
be done in practice. In my case, running the coax straight down
to the ground and then over the the shack seemed to be ok, as the
F/B test results indicated.
It seems to me that the same physical arrangement of wire/coax connections
on the box for K0FF's proposed transformer box design would work
in either case (coax routed away from the antenna horizontally or
straight down to the ground). |
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