Topband Folk:
I've just returned from a stay at the Signal Point station
on Curacao, and noticed something interesting during the
ARRL 160 Meter Contest.
I took parts for a pair of phased pennants to use during
CQWW CW and the ARRL 160 Meter Contest, but the space
constraints allowed the installation of only one pennant
rather than the pair.
There was a tropical storm in the area, and noise was fierce.
On Friday night, noise was 40 over on the transmit antenna, and
+15 to +20 on the Beverages. By backing off of the RF gain,
minimizing the preamp, cranking in 18 dB of attenuation, and
using the filters, EDSP, and IF shift, I was able to maintain
some sense of sanity and still work 400 stations Friday night,
although it was two or three characters at a time. Not fun!
A surprise was that the single pennant, although preamplified
to make it's signal output about the same (to the ear, before
the storm) as the Beverages, seemed to be far less responsive
to this storm noise than were the Beverages, while presenting
usable signals! I don't recall having seen a previous report
of this, but it bears some investigation.
Does anyone have a theory? Was this just an "observational
anomaly", or is it a useful characteristic? Could it be due to
the loop nature of the pennant, or the difficulty in getting
a good ground for the ends of the Beverage on the coral/rock
land of Curacao?
The pennant was pointed at the US East Coast (~350 deg) and
the US/JA Beverage (650 feet) was pointed at around 330 deg, a
difference that should be insignificant. It was located 400
feet from the station and the transmit antenna, and was fed
with new RG-8X. The mast used was heavy-duty fiberglass
military surplus sections, originally found on eBay but
eventually purchased for just $3 per 44-inch section. It's
installed with the bottom six feet above ground level. A
diagram of the pennant and a photo are at
http://home.columbus.rr.com/jmaass/Radio/PJ2T_Pennant.htm
It was nice to be able to have the pennant pointed to the Pacific
for CQWW CW, and then rotated around to the USA for the ARRL 160
Meter Contest by just walking the pointy end around and re-guying,
a five minute project (try that with a Beverage!). The "trapezoid
shape" in the photo is caused by needing to take out slack in the
wire caused by differences in the ground level when rotated.
73,
Jeff Maass K8ND
Caribbean Contesting Consortium - PJ2T
http://www.pj2t.org
http://home.columbus.rr.com/jmaass/Radio/PJ2T_Aerial.htm
_______________________________________________
Topband mailing list
Topband@contesting.com
http://lists.contesting.com/mailman/listinfo/topband
|