Stew Perry Topband Challenge
Call: K7IA
Operator(s): K7IA
Station: K7IA
Class: Single Op HP
QTH: DM62 (NM)
Operating Time (hrs): 1:31
Summary:
Total: QSOs = 80 Total Score = 319
Club:
Comments:
We purchased this NM canyon QTH in 1996 first, and THEN I discovered contesting!
The surprise has been how well one can do on higher bands with directional
antennas and modest power (1 KW--all off grid, solar power here). But such has
not been the case on 160 meters despite a shunt fed, top loaded (2 el 40m) 92
foot tower with 66 quarter wavelength radials and bidirectional Beverages for
EU/ZL and JA/S. America. Our canyon runs nearly NNW, is broad at the
ridgelines (about 3/8 mile), and is about 500 feet below the ridgelines.
House, shop and tower bases are about 250-300 feet below ridgelines (which are
10-12 degrees above tower bases). Not many ops can inspect the TOPS of their
yagis as they drive down their access lanes, but we can.
Both Beverages are 550 feet in length and employ 450 ohm ladder line. But the
canyon terrain is "uneven." The JA/SA Bev's contour undulates within
25 feet of a level line, and it works fairly well in both directions. But the
EU wire is nearly parallel to the canyon's direction, and therefore, it crosses
perpendicularly the little ridges and ravines ("draws" in local
speak). No part of the ladder line is level--only a tangent at a point. Near
the reflection end, 200 feet of the ladder line crosses a wide draw that is
about 50-60 feet deep. I have laid grounded counterpoises across the draw, six
feet below the ladder line. but I think all that did is to convert 200 feet of
Beverage from an antenna to a transmission line.
Summary:
1. Nothing ventured, nothing gained, nothing learned.
2. Beverage Rx antennae are far quieter than a vertically polarized Tx
radiator used for receiving and therefore far easier on the ears in QRN as in
this weekend's event.
3. Canyon terrain is no doubt responsible for the generally poor
directionality of my Beverages, because the canyon ridgelines
"filter" low angle incoming RF signals, which are the ones
responsible for directionality of Bevs built on level ground.
4. The literature recommends grounded counterpoise wires (making a
groundplane) for "modest" dips in earth's terrain.
"Modest" is undefined. My draw under the EU antenna is beyond any
notion of modest, proven by experiment here!
5. If you must choose a canyon location, then choose a flat-bottomed canyon
whose nearest ridges are at least 100 miles away. It isn't wise to construct a
contest station in a hole in the ground.
This TBDC was a disappointment, compared to past years. I was limited to
S&P and made most of my meager Q-count that way. I prefer running, of
course, but the EU Bev just couldn't make enough microvolts for me to copy
complete callsigns or grid squares. I was an alligator, and I left more chaps
hanging than I was comfortable with, so I swept the band in S&P and hung up
my spurs. My apologies to the stalwarts who tried again and again to complete a
QSO. We are off grid and have no line noise, and there are no nearby neighbors,
so I have no excuse other than poor ears.
I am toying with the idea of a Shared Apex Loop Array (the Array Solutions
SAL-30). Unlike city dwellers, who use them because their footprints are
smaller than Beverages, there's plenty of space here, but it's the
"wrong" space. However, there is a nearly level "bench" on
the mini ridge about 400 feet south of the shack that would accomodate an
SAL-30. It would have to be elevated to about six feet to allow the deer and
cattle to wander through it. If anyone reading this has some SAL experience to
offer with the above discussion in mind, I would be grateful to hear from you!
Otherwise, it looks like 160m will be kaput for me...
73, dan
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