Field Day 1997 Report
This year four members of SWSA, Steve Bosbach (KG5BR), Crystal Bosbach (N5LEQ), Ben Thornton (WD5HLS) and one other ham, operated Nude Field Day number 2, this time from Bluebonnet Naturist Resort, just outside Decatur, TX. Bluebonnet has the right combination of easy access and hill top location with enough open space for launching balloons without running into trees. Did you say balloons? Yes, that was the plan, but the best laid plans of mice and men often go.........bang! My idea was to lift dipoles to incredible heights above ground on 80 and 40 using helium weather balloons. There were a number of unforeseen problems with this, unmentioned in the sparse literature about balloon launched antennas. More on this later.
Even before we could get on the air, a thunderstorm moved into the area and robbed us of at least 90 minutes of air time. We retreated to the camp site to set up tents before the deluge hit. With tents up and rain flys on, we mingled in the clubhouse as the skies opened up and soaked the grounds for the next half hour. After re- connecting coax with the last storm cell in retreat, we started piling up the contacts in earnest. 20 meters was in good condition as was 15 meters, and even 10 meters was productive for much of the day. We all rotated through the operator position taking turns operating, logging, and duping. When we weren't busy at the rig, we were free to swim, walk the nature trail, soak in the hot tub or take in some of the fine cooking from the kitchen of the club house.
Although we started with QRP, we soon abandoned it as our antennas were compromised on the lower bands. Ben had brought his 10-20 meter vertical which worked great from the hill top. We used a mobile antenna for 40 meters as the other bands went to bed, but by 1 AM both solar powered batteries were down to 11.2 volts and I dared not push them any further. Transmit audio was also probably beginning to sound pretty rough as the battery ran low. We shut down the operation and retired until the sun came up. I turned the van around so the solar panels could face the morning sun and we all went for a swim in the pool and soak in the hot tub as the batteries recovered. By 9 AM the voltage had come back to 13 volts and we were back on the air. We even held a frequency for a while on 15 meters, clicking off two contacts per minute!
Just a note about our charging system. I use two 22 watt solar panels on
the roof of the van charging two 100 amp hour gel cell batteries, one of
which is the van's starter battery. Although the batteries need much longer
than a couple of hours to charge, with full sun on the panels, I have a
net gain in charge even while operating with 100 watts out! By the time
the contest ended at 1 PM, I had a full charge again on the batteries!
Getting back to the balloon project, there were several things that should have been done differently. One mistake was to fill the balloons before we really needed the antenna. We also made the mistake of lowering them to near ground level when a thunderstorm moved in. They would have been safer at maximum height above ground where they couldn't make contact with anything! The balloons didn't last through the afternoon as they got slammed around by the thunderstorm winds into a ground littered with sticker burrs! We also discovered that old, surplus weather balloons are very fragile. We actually blew a hole right through the rubber material of the balloon with the force of helium from the fill tank! Be careful to position the balloon so that the jet of helium escaping from the tank is aimed at the center of the balloon interior and not the edge! We had also used wire ties to fasten the antennas to the balloons and probably lost our one remaining balloon to a sharply trimmed edge on a wire tie. All sharp edges must be covered!
We also had a problem with the balloons lifting the combined weight of
the antennas and coax. Even with about 80 cubic feet of helium in two balloons,
it was just barely able to support our 40 meter dipole made from copper
clad #14 and fed with RG58. We either need to go to a much larger balloon
or use a lighter arrangement. Going to a larger balloon not only entails
the purchase or rental of a large balloon, but helium is not cheap either,
and the larger size will eat into your pocket. I purchased 120 cu. feet
of helium for $37.50 with a $100.00 deposit on the tank. This is just enough
to inflate two 6 foot weather balloons. A single eight foot balloon however,
uses over 230 cu. feet! My plan for next year is to use full size wire
J antennas for 40 and 80. They could be made very light with #18 copper
and 450 ohm ladder line for the 1/4 wave matching section, keeping all
the coax on the ground. The matching section doesn't have to be lifted
either, as only the antenna above the matching section radiates. Tall stand-off
insulators shoved in the ground could support the ladder line and provide
part of the transmission line distance back to the transmitter.
The final result of our Field Day effort was only 738 points, 269 voice contacts including 38 states and 1 Canadian province. Even with the low score, it was a lot of fun doing Field Day at a Naturist site, and the hams in Hill Country Nudists would like to begin planning for a larger operation for next year at the same site, Bluebonnet Naturist Resort. We would like to invite any hams in the region or Naturist SIG across the country to participate with us in Field Day 1998.
