Dear Topbanders,
The K6SE "DXpedition" to Koehn Dry Salt Lake appears to be a success in
demonstrating what excellent soil conductivity means for a vertical
antenna on topband.
We arrived at the site at about 8:00 AM local time and had the antenna up
by 10:00 AM. Most of that time was spent installing the screw-in guy
anchors because the salt, which was very wet a few inches down, was
rock-hard. We were very concerned about the predicted high winds for
southern California which would prevent us from installing the antenna,
but only a slight breeze prevailed during installation. After the
antenna was up, the breeze subsided and it stayed calm all weekend, with
high temperatures during the day in the 60s (F).
The antenna used was a 70-foot (21.34m), U.S. Army surplus 5-inch
(12.7cm) diameter push-up mast which is quite easy to install, even for
one man (if there is no wind). Three 50-foot (15.42m) equally-spaced
top-loading wires were attached to the top of the mast, each sloping
downward at a 45-degree angle. Modeling showed that this configuration
would be 1/4-wave resonant at 1830 kHz.
The top loading wires served as guy wires. Three other sets of guy wires
were used which were insulated from the mast
The modest ground for the antenna was only three short radials. The
outer ends of the radials were connected to the metal guy wire anchors
which were 32 feet (9.76m) from the base of the antenna.
A slant-wire shunt feed system was used, with the slant wire attached to
the mast 11 feet (3.35m) above ground and the bottom end of the slant
wire about 10 feet (3.05m) from the base of the antenna. Two vacuum
variable capacitors in an omega match configuration were used to match
the antenna to 50-ohm coax. A 1-foot (4.72cm) metal stake was driven
into the ground at the feedpoint with a wire running from there to the
base of the antenna mast.
A 700-foot (213.4m) Beverage made of high-loss steel wire was installed 3
feet (0.91m) above the salt toward W1/W2-land. We were also interested
in seeing how a Beverage would perform above highly-conductive soil.
After we got the antenna tuned and the station set up in the motor home,
we immediately heard an s7 noise level on the band. Our 6kw diesel
generator had heavy-duty line filters on it and the Beverage, whose
feedpoint was only a few feet from the generator, was quiet with no
noise. It is now thought that our noise was simply "band noise", which
was 2 S-units "quieter" than the home QTHs of K6SE and K6NDV!
When the contest started, our first QSO was with N6CMF at 0200Z while we
were running 50 watts. Encouraged, we fired up the Alpha 91B and ran
about 1300 watts output for the rest of the contest.
Problems developed almost immediately. We forgot to bring an extension
cord with multiple outlets, so the 6kw generator 117VAC output was
connected directly to the motor home. The FT-1000MP and laptop computer
(used for logging) periodically would lose power because the circuit they
were plugged into was on a ground-fault interrupter circuit breaker that
kept tripping. The last time this happened (1-1/2 hours into the contest
and about one hour before sunset), the FT-1000MP would go solid key-down
whenever we tried to send from the laptop computer. Keying was okay
directly from the paddle to the MP, so either the computer or the
interface (2N2222 transistor) was bad.
We tried another laptop, but the keying problem prevailed, so I sent all
CW manually using the paddle and with the other hand I entered the QSOs
into the log on the laptop. Anyway, 1-1/2 hours was lost in transferring
the log files from one computer to the other and correcting the power
problem.
Will, K6NDV had to run home to take care of other commitments while this
took place, and after dark it became quite cold. We didn't know how to
turn on the furnace in Will's motor home, and the radio gear was not
enough to warm us up, so my fingers started to freeze and it became
increasingly difficult to manipulate the paddle and the keyboard. I
finally gave up at 2:00 AM (1000Z) and retired to my tent trailer where
the thermometer read 21 degrees F (-5 C), and snuggled up in my sleeping
bag. Will woke me up at 5:00 AM when it was a chilly 16 F (-9 C). He
had returned and turned on the motor home furnace and brought another
keying interface, so I got another 1-1/2 hours of operating in before
sunrise at 1445Z. (It was still COLD!!!)
Despite the large loss of operating time, 235 QSOs were made the first
night.
The second night began for us about 1/2 hours before sunset. Will had to
go home again because of other commitments, but he turned on the heat
before he left. I actually had to take off my winter coat, hi. Things
went quite well from then on until it became cold enough to put my coat
back on. The furnace couldn't keep up with the rapidly falling
temerature outside, so I had to take frequent breaks to stretch my legs
and warm up my hands by the furnace. 238 more QSOs were made the second
night, however.
Although we had planned a multi-op effort, Will had those other
commitments and our other planned operator (KR6C) also couldn't make it,
so we ended up being in the single-op category with K6SE as the sole
operator.
The preliminary final totals are 473 QSOs in 64 sections and 4 countries
for a total of 70,920 points.
DX worked was XE, ZF, UA0 and JA. The JAs were unbelievably strong the
first night, but very few of them. Any JAs heard on the second night
were already worked, but this time they were very weak.
FO5N?? answered one of our CQs the second night and gave us a report, but
he QSYed before we could get his complete call, so he didn't get logged.
I heard a W5 on 1814 kHz the second night desperately trying to get the
call of VK6HDE ???? correctly, but he never did. I strained to hear
VK6HD, but never heard a trace of Mike.
The Beverage turned out to be quite useful on the first night, despite
some criticism about its usefulness over highly-conductive soil. Early
into the contest, the Beverage was poorer than the vertical, but after
about 11:00 PM when I tried to identify a K1, I switched to the Beverage,
and there was Jeff, K1ZM solid copy! After working him, I switched back
and forth between the two antennas and there was no doubt -- the Beverage
was considerably better. This lasted for about two hours, when the
vertical again became the best receive antenna for the east coast. The
vertical outperformed the Beverage throughout the second night. I assume
that the changing angle of arrival of signals was the reason for this
interesting phenomenon.
A Beverage over highly-conductive soil likes to hear signals arriving at
a high angle. The top-loaded vertical used has a max-signal elevation
angle of about 25 degrees over "average" soil, and 8 degrees over salt
water. Our soil conductivity, even in the far field, was better than
salt water!
During operation, one W9 in Illinois commented "wow, big sig". Another
in Texas said the same. I never get those kind of reports from the home
QTH, so I have the distinct feeling that a simple vertical over salt
works better than my phased towers with rusty radials over desert soil.
E-mail comments received after the contest:
VE3OSZ (ONT): "Up to s6, only W6 heard"
N5UL (NM): "S9 +15. 1 or 2 other W6s were stronger at times."
K1PX (CT): "S5 to s7. Other west coast best sigs were s3 to s4."
W1TO (WMa): "At least 2 s-units stronger than any other west coast
station I was hearing at the time of our QSO."
W0OPW (MN): "S9 on my meter, a very big sig. Comparable to the W8s and
W9s. Heard N6AA later at s3."
K2WI/K2TOP: "K7RAT s3-4, N6SS s3, K6SE s1".
K7RAT is in Oregon and N6SS is in Arizona with a 4-square. Don't know if
Rob heard any other W6s to compare us with.
Jim, K1PX also suggested that we put up a 4-square at the site. We are
indeed considering that possibility using balloon-supported full-size
1/4-wave verticals!
We wish to thank the U.S. Bureau of Land Management (BLM) for giving us
the permission to use the site. Their main concern (other than harming
the desert tortoise population - we saw none) was low-flying aircraft
from nearby Edwards AFB or China Lake NAB. Apparently both bases fly
their fighter jets on training missions in the area, but we saw none
during the weekend (although we heard many sonic booms).
It was an experience, to say the least, and we enjoyed it despite the
problems. We are planning to return there for the Stew Perry using
Will's call.
A photo tour of the "Saltdale DXpedition" is available on K6NDV's Web
site at:
http://www.angenent.org/Koehnhtml/saltdale1.html
I'm sure the photos of the site and antenna will interest you.
73, de Earl, K6SE
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