Repairing Antennas With a Chainsaw

During a windstorm a week before Christmas two of the reversible Beverages failed to reverse. This often happens when the wind brings down a tree, usually dead or dying, or the long wires twist and tangle due to oscillation. It's become a regular part of station maintenance. Although I hate doing it it's still more convenient than alternative low band receive antennas. So I gripe and carry on.

Unfortunately this happened the day before the RAC Winter contest (Dec 20). Top band isn't a popular choice for that contest so it wasn't critical, besides which the weather happened to be unpleasant. Since ours was a two-person multi-single (M/S) with just one transmitter I headed into the bush during the contest to inspect the Beverages while he continued to operate.

As I feared the outage of two Beverages on the same day was no coincidence. A dead tree had fallen across both antennas. This was possible since the east-west and northeast-southwest reversible Beverages cross. You can safely do that with Beverages since their radiation resistance and mutual impedance are very low.

With the wires scrunched together the differential (transmission line) mode for the reverse direction fails while the common mode direction continues to function. That is, if the wires don't break. Reversible Beverage operation is explained in an earlier article and in ON4UN's excellent book: Low-Band DXing.

The above picture misrepresents the scale. The trunk of the dead tree was shoulder height. It was massive and could not be shifted more than a few centimeters by hand. That would have been a bad idea in any case since the wires were trapped beneath it. 

In a way this was fortunate since the wires (for the east-west Beverage) weren't pulled downward too far. That was likely why the #17 aluminum electric fence wires that I use didn't break.

It was a long trudge through the bush and fields back to the house (~300 meters) since the damage was near the far terminations of both antennas. I returned to the contest while I charged the chainsaw battery. That afternoon I returned to the site to deal with the tree.

It took less than an hour to do the job, including walking there and back. Chainsaws are wonderful tools when you live on a property like mine. Nevertheless it was important to work methodically for safety to myself and the Beverages. A lot of limb clearing was done before I started work on the trunk. Only then could I safely free the wires. Notice how they bounced back into position. Once they were clear I could finish chopping up the tree without further risk to the antennas.

The bush is an unmaintained area of my property. It is many acres in size. I only chopped the tree into small enough pieces to toss them out of the immediate area to make it safe for the antennas and for walking. Although most of the wood can be used as firewood it is not easy to haul it out of the bush. It will likely be left where it is.

I walked along both antennas to check for additional damage. That's a lot of walking since these are long antennas: 175 and 165 meters. The PVC pipe that supports the crossing antennas was still bent because the wires had been pulled out of position. It took only a minute to knock the pipe back into position while straightening the antennas. 

The wires that had twisted together in the accident were separated. The pipe still has a slight bow in it though not enough to be a concern. Beverages are not fussy antennas. Most of the PVC support pipes are similarly bowed.

The evening after the RAC contest I tested the Beverages. Both worked as they should in the forward and reverse directions. That was the only successful antenna repair job for which the only tool I used was a chainsaw. Hence the somewhat whimsical article title.

Early in the new year I'll return to the bush and spend a few hours clearing trees and limbs that threaten the Beverages. There are many -- it's always surprising how much growth there is over the summer, even during this drought year. Brush clearing has become an annual winter ritual.

The Beverages worked perfectly a week later during the Stew Perry contest. As always I am amazed how well these simple antennas can pull weak stations out of the unrelenting noise on top band. It is quite likely that they've added more multipliers to my contest logs than any other antenna in my station. They don't get used a lot but when they are they shine.

I thought I should end this tale with a cautionary note. If you have an antenna that resonates too low in the band and it must be shortened, I advise you to put down the chainsaw. This is a case where more conventional tools will serve you better, and keep you out of the hospital. 

Of course I jest. Still, be safe out there. Chainsaws are wonderful tools but dangerous in careless hands. They've become as essential a tool at my station as winches, wrenches and soldering irons. 

There are many online resources and videos by experts on the selection, safe handling and maintenance of chainsaws (battery or gas). Felling dead trees can be especially dangerous. I won't presume to teach those skills.