I took a week-and-a-bit off from work and traveled to ... home. Loved the accommodations and the meal package! I also made a pretty big dent in the to-do list, mostly on the antenna section.
The antenna to-do list was a little longer than before due to the recent
"wind storm". In addition to a number trees (most already dead), the
wobble-stack took a bit of a hit. This was due, undoubtedly, to the crappy guying job that was in place prior to May 10. In addition to resurrecting the VHF antennas and making the wobble-stack decidedly less wobbly, the wire antennas were worked on as well.
In the case of the wire antennas, one of the dead trees that came down ended up leaning against a live tree that supported the
Spi-Ro D-52 40-80 dipole, so we started there. The tree that fell, or tried to fall, was where the support rope for the dipole terminated. The tree it fell into is the one whose crown supports the rope that supports both the 40-80 and WARC-band dipoles.
We thought it best to lower the antenna (from the other end) lest too much tension snap something especially during the tree removal process. Since the 40-80 crosses the 80-10, we lowered that, too. The 10-m dipole has been supported at one end by the wobble-stack, so that was already down. At this point, the WARC-band dipole was still up.
We borrowed the neighbor's tractor (and the neighbor) and got the dead tree moved to a safer horizontal axis. That done, we got the 40-80 and the 80-10 back in the air. I still saw SWR issues on the 40-80, though, which I thought I'd blogged about but haven't. So a little diversion.
I started having trouble with the
Spi-Ro D-56 (5-band trap dipole) back in 2008. See
here and
here. Basically, one of the traps that makes it resonant on the 10-meter band is dead so I needed a new antenna. Having had good service from it and the Spi-Ro D-314 WARC dipole, I thought I'd get another Spi-Ro. Unfortunately, they neither answered the phone nor email. They did have an eBay site (through a third party, as far as I can tell) so it appeared that they still sold antennas. Looking at their site, they had a D-52 trap dipole that promised coverage from 80 through 10 with only two traps and 20 or so more feet of copper. So I ordered one.
Well, it seems they were
WAY optimistic on covering 20-15-10 meters. I eventually put up a home-brew dipole for 10 and continued to use the D-56 for 15 and 20.
With that many antennas, switching bands was becoming a hassle, so I acquired an Ameritron RCS4 switch. Within a few months, I had trouble, namely weird SWR issues that
I initially blamed on the switch. It wasn't the switch.
Anyway, back to the story. SWR was wonky on the 40/80. Worse, it was really bad on the 80-10. OK, but I had other things to do.
With the 40-80 and 80-10 back up, I got the 10-m dipole off the ground (it had been supported at one end by the aforementioned wobble-stack) and supported by the Davis weather station's tripod on the roof. This meant that 1) the antenna was now higher leading to better signal reports on the weekly 10-m net and 2) it needed more that the 25' of feedline that it had so that it wasn't pulled horizontally. I left the latter for another day.
While we were tying the ribbons on having the 3 wires back in the air ... the WARC-band dipole fell down! Upon inspection of the support rope, we found fraying. This was undoubtedly due to the movement of the Sycamore tree used as one of the supports.
Look back and you'll see that this was not totally unanticipated. Something else to leave to another day.
In thinking about the SWR issue on the 40-80 antenna, it occurred to me (finally!) that maybe it wasn't the switch and that maybe it was the coax. Since this was partially-air-dielectric Belden 9913, that was a distinct possibility. It's well known in the amateur radio community that 9913 has to be really well sealed at the connector ends lest water accumulate in that dielectric space. Even if you're careful, you may
still get condensation.
To test, I substituted 68' of LMR-400 for the 40 or so feet of 9913. Initial tests were good so I left it for a few days.
On a subsequent day, though not sure which, I mounted the 2-m loop, the 2-m beam, and the rotator on the top of the mast. I had already prepared a new set of guys, ones that I hope will prevent a repeat of the wind-driven collapse of the VHF mast. Not only are the guys themselves better, but so are the anchors.
We also got the WARC-band dipole out of the tree. We debated whether or not to move the anchor from the Sycamore, but decided to leave that until another time. There are other candidate trees near the Sycamore that don't sway as much.
Next, the saga of 9913 and the VHF stuff ...
Back to the 9913. Once it was down, I put the multimeter to it and found that it was shorted. That's a problem obviously. I put I cut off the connector in preparation for putting on a new one, thinking that was the issue. I used my DXEngineering prep tool and discovered that the center conductor was an odd shade of black. OK, so this *is* a water incursion problem. I wonder? I cut off 6" and blew into the end. Lo and behold, a drop of water.
Once up on the roof, I found out that the piece attached to the D-56 had good reason to have high SWR - in several places, the cable was chafed down into the dielectric! The way the cable runs, it comes down straight to the roof ... where the asphalt shingles abrade it as it moves with the wind. I have yet to solve this issue. The 40/80 could also potentially suffer from the same issue, but we solved it by moving the antenna closer to the NE end which allowed the cable to hang away from the roof.
Sounds simple, but took place over a couple of days. Temps were in the 90s and being on the asphalt roof did not help!
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