Another Tower Appears

The ham that keeps an ear on the ground will find that many used towers are available. People downsize their possessions when they get old and, as we know, the average age of hams is quite high. Those hams that delay downsizing end up passing the torch to their friends and family via estate sales. It's sad but understandable. Just don't let that sentiment get in the way of a good deal.

Certainly there are some who ask an unreasonably high price. But for every one of those there must at least 3 that are free for the taking (down). Some may already be on the ground. If you don't climb you may know a fellow ham who does. Do him a favour and perhaps he'll do you a favour.

The challenges are twofold:

• Taking the tower down
• Taking the tower home

Earlier this year a friend asked for help to take one of his towers down. I was happy to oblige even though I didn't expect to take the tower for myself. My first thought was to find another ham who needed a tower. There are surprisingly few of them since many of the newer hams make do with small antennas to avoid the hassle with the municipal authorities, neighbours and family. They just want to avoid the effort and worry in their busy lives.

This particular ham is not downsizing. Indeed, he has a large contest station. This small tower was at the family home, and his big station is at their rural property. One day this spring I and another contester friend headed over to do the job. Since he had helpfully already removed the antennas and rotator the job only took a couple of hours. That left us plenty of time to chat and eat.

That's me posing on the tower after all but the last section was down. Dave VE3KG is on the left and in the centre is Vlad VE3JM. The tower is Vlad's. The photo was taken by Vlad's wife Marija. After Dave left, Vlad and I spent another hour digging the bottom section out of the paving stone patio to unbolt it from the base stubs. Although a below grade concrete foundation is generally a poor choice, there was good drainage and no rust damage to the section after more than 20 years.

I don't have a large enough vehicle or a trailer so I had to wait until a friend could assist. Vlad was in no rush so I delayed while I worked on other things. Earlier this month, Brian VE3CRG and I took the seats out of his large van and moved the tower to my place. A fair amount of driving (and gas) was involved since the 3 of us live some distance apart (3 adjacent grid squares).

The DMX line of towers are self-supporting up to 8 × 8' sections, with sections from #8 (the largest) to #1 (the smallest). The DMX product is well known to Canadian hams. While not commonly seen outside the country there are similar light duty self-supporting towers made by others, including Rohn in the US.

The driven element of my 3-element 80 meter vertical yagi consists of sections #6 to #1, with a guying bracket. I first purchased that tower to support a yagi at my previous QTH.

The picture at right shows the #7 and #8 sections of Vlad's tower after they were unloaded. These are the key sections for what I have planned. The other sections will be stored until I find a use for them.

The first application I have in mind is as part of the rebuild of the 80 meter yagi. The tower that currently forms the bulk of the driven element, and wire elements support, stands about 14.5 meters. The additional length for make a full ¼λ vertical on 80 meter is a stinger. That stinger is a weakness, and there have been problems. That said, the current stinger has done very well.

With the #7 and #8 sections the tower portion of the driven element becomes about 19.2 meters tall. The tower base must be changed to accommodate the larger base section (currently a #6). The stinger (if we can still call it that) will be less than 1 meter. A second guy station will be added for stability. I can reuse the improvised design from its original installation.

The electrical design of the yagi remains the same. It is only necessary to adjust the pipe at the top to resonate as before, and provide a 2' non-conductive pipe above it to support the 4 wire elements as before. However, I plan to take the opportunity to make long-planned improvements to the array. These include altered wire element design to improve gain and directivity. 

With a switched, side-mounted stinger at the top of the tower and and top loading I can have a far more efficient year-round vertical for 160 meters than the current base loaded mode of the 80 meter yagi's driven element. The 80 and 160 meters improvements do not have to be done at the same time. Both can be done during the colder months when work on the other towers and antennas is paused.

As for the other 4 sections of my newly acquired tower? That is yet to be determined. I have tentative plans for another tower, possibly for VHF or WARC band antennas. It is easier to locate #1 and #2 DMX sections than #7 and #8 sections, so when those cross my path I will have enough for a suitably high tower. For the present the extra sections go into storage.

Blog note: It's summer. My time to write for the blog is severely budgeted, as is usual for this time of year. Backlogged articles will appear, eventually. I may also be slow to respond to email, and I have several in the inbox awaiting my attention.