Tuesday, October 13, 2009

Winter Wonderland

The snow is on the ground and the temperatures are below freezing. That traditionally means it’s time to start doing antenna work. I don’t really know why we (actually me) can’t get our (my) act together and do it during the summer. There’s always so much going on when the weather is nice and a never ending litany of excuses. It’s too hot, it’s too cold, it’s raining, there’s too many bugs, there’s better things to do, etc, etc. Once October hits, though, the situation seems to reverse itself. Yeah, it’s 5 below zero outside -BUT- it’s only gonna get COLDER. And DARKER. And WINDIER. And CQ World Wide is only a few weeks away now… Better suck it up and get onto the antenna work before it’s REALLY miserable out there.

So I spent last weekend up on my roof putting up a 23 foot vertical antenna for the low bands and an 18 foot vertical antenna for the noise sensing antenna to use with my MFJ-1025. Before I got started, I modelled several different rooftop antenna and radial configurations in EZNEC. It’s quite amazing what little things make a big difference and what things make very little difference. The end result of the modelling was to put the vertical on a tripod mount at one end of the roof with two 18 foot radial wires down to the eaves and one 33 foot radial wire along the ridge of the roof. This gave a reasonable performance and efficiency on all bands. I modelled it with a few more and different length radials but it didn’t seem to make much difference. I fed the antenna with a chunk of LDF2-50 hardline I had handy and it loads up quite easily with the internal tuner on 40-10 meters. I can load it for 80 and 160 meters with the external tuner but I really don’t expect too much on those bands. Judging by the contacts I’ve made so far the modelling seems to be valid. I haven’t had a chance to play with it too much yet but I have made a few contacts on several different bands and on 17 meters I even got a 10-over-S9 report from a JA station and worked the TX5SPA expedition in the Austral Islands.

The weekend after the vertical went up it was time to start on the big project. Originally scheduled for late June, Wally and I had planned to permanently mount the TH6DXX yagi up at the contest site. The setting for that is a 40-foot guyed tower on top of a 60-foot high water tank. We had hung temporary wires from the water tank last winter during contests but hadn’t exactly figured out how we were going to get the big yagi up to the top of the tower. I’ve done enough tower work to know there was no way I was going to climb it. I don’t like climbing towers to begin with and old, rickety, light duty guyed towers are a non-starter with me. However, one day last spring when we were taking down the wire beam after the ARRL DX contest, I noticed that there was a hinge on the bottom edge of the steel pocket that the base of the tower sat in. Looking more closely, I realized that if the bolts were removed from the bottom plate it would swing open and allow the tower to drop through along the side of the water tank.

So this weekend we went up and bolted a small winch to the edge of the base frame and eventually got the tower lowered down, the old un-used VHF antennas off, and the top section removed. We might have actually pressed ahead and installed the yagi but even though it was only a couple of degrees below zero the wind was howling all weekend. Once all the demolition was completed we decided to call it a wrap for the weekend and enjoy the Canadian Thanksgiving holiday.

Today I got the rotator mounted in the top section and we should be all ready to put the yagi up on Saturday. Wally, VE8DW, has been taking pictures so I'll post the results of our efforts next weekend when we're done.

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