ARROW Communications Association

Now to consider the antennas again.

The 10-15-20 dipole I suspended in a tree last Fall had become very lossy, and I suspected water in the coax. In fact, it had become quite deaf, so I lowered it down to the ground (with difficulty, as both the rope and the feedline were tangled in tree branches by the winds of Winter). As it turned out, the reason it was deaf was that the tree had snapped the center conductor connection, tearing the wire from its ring lug. No wonder it wasn't hearing very well any more ...

I completely disconnected the antenna and moved it to the patio behind the house, and extricated the feedline and rope from the trees with the aid of the longest pole pruner I could find. I removed all the coax from the woods, and am thinking hard on how I might put up the horizontal loop I have been daydreaming about all Winter.

Putting up the horizontal loop will be a challenge. The trees are tall and thin, but because they are near the edge of the woods behind the house, many have branches at the 20-40 foot level, even though their tops are easily 90 feet up if not >110. This is going to make creating a nice level loop difficult. In fact, I am thinking it will be a loop made of wire that zigs and zags between higher and lower branches - suspended over the high ones and caught under the lower ones.

I will try to keep the wire as close to the tree trunks as possible to minimize the stress of being slapped and pulled around by branches, and will suspend at least a couple of corners by running the wire through wire loops or metal loop-clips on the ends of support ropes, with weights hanging from the ropes to allow them to move up and down as the wind moves the trees. The wire loops will allow the antenna wire to slide back and forth through them, providing more compliance in the system to cope with the stresses of tree movement.

In the end, though, the loop will probably be a circle of sawtooth-patterned wire with as much as 20-30 feet of up-and-down variation in height. It will probably perform as if it was a flat horizontal loop at a height that will be the average of the ups-and-downs, so I hope to be able to establish that average somewhere around 40'. I also hope to have about two wavelengths of wire on 80m up there.

For my first loop I will try out my favorite, almost totally invisible, 18 gauge magnet wire, and see how long before it breaks. If I suspend it so as to forgive as much tree movement stress as possible, it might last a year, and if it breaks too soon for me, I will replace it with some stronger stuff, maybe black-insulated 14 gauge wire, or even some copperweld (steel-core copper wire - very strong). It will be a little easier to spot in the trees, but not much.

Eventually I hope to put an autotuner on the ground beneath the feedpoint, connected to the loop with some (probably homebrew) 450-600 ohm ladder line. I have an AH-2 autotuner I got cheap (apparently damaged) at Dayton last year, and need to send it to one of the best repair services for a diagnosis and (hopefully) repair. It might have been a ripoff, though there are no obvious lightning-charred parts on the circuit board. It just doesn't power up at all.

Until I get that squared away I will probably feed the antenna with coax or (as I did before) some clear-jacketed speaker wire, which has a characteristic impedance around 90-100 ohms, typical of horizontal loops. That's not enough of a mismatch for me to worry about too much, but I expect the autotuner setup will be a little better. Lightning protection if I am going to run the speaker wire into the house will be a challenge, though. For that I will probably run the wire through the NEMA box and tape or wire-tie it to the edge of the grounded copper plate as a makeshift spark gap. That's not a great solution, but it's probably better than nothing. When the autotuner is in place there will only be coaxial cable coming back to the shack, and that will connect through one of the Polyphasers, so that will be optimal.

So, the station construction efforts go on. I am also thinking hard about my operating desk setup for the station, as a number of nice options are available, though most are quite pricey. Of course, the wife will be involved in the selection process as befits her aesthetic skills.

Good reception! 73 de kt8k - Tim