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Antenna topics

I recently did some antenna work around the farm here – a whole 0.19 acre of antenna ranch. I took down a 40-meter full-wave horizontal loop (basically a 140 foot long piece of wire stretched out by ropes in the trees to almost encircle the house. It was OK on 40 meters and below, and I actually worked all continents on it. A pretty good antenna.

I replaced it with an 80-meter full-wave horizontal loop antenna ( a 275 foot long piece of wire). and I fed it with the same coax and same impedance-matching balun that I used for the 40 meter loop. I also replaced the 80-meter dipole, which had gotten damaged by a couple of winds storms (one side had actually broken).

My radio mentor (or “Elmer”), Bob, told me I’d have much better luck with the loop if I fed it with a balanced line and a tuner.  It took me a week to bring those plans to fruition.  I had to order the tuner, and before ordering the tuner was the research into which tuner to buy, and the gut-wrenching decision to part with $200. I have a ham radio “war chest”, so the money doesn’t come out of the grocery budget, but still…

Last weekend I got the tuner in the mail, so I took a few hours to do the installation. I converted the antenna feed point from the impedance matching balun to balanced window line, and brought the window line into the shack and wired it up to the new tuner. Eight more connections on the other end of the tuner completed the installation. ( I really need to mount it but for now it’s just supported by its many cables).

I didn’t get to work with it last weekend – the installation took longer than I’d anticipated. That’s a common occurrence around here, don’t you know. But the little playing I did with it seemed to indicate that it wasn’t working. So all week I thought about how to go about troubleshooting it.

I got around to debugging today. The SGC book recommended building a dummy load with a light bulb and way too many components to justify it – alligator clips, AC sockets, light bulb sockets, AC plugs – the works.  I grabbed an old drop light whose cover had gone missing.. A couple of spade lugs later, I had a 60W dummy load. I could have gone for 100 if I’d had the gumption to walk down and up two flights of stairs.

So the dummy load gets attached to the output of the tuner. Press the Transmit button. Nothing. I’d expect the tuner to click like mad. Flick the switch on the lamp socket. Press the Transmit button. Nothing. Unscrew the bulb, turn on another lamp. Ah, light, so the lamp is OK (I should have done the same to the drop light before cutting off its AC plug!) Screw in the test bulb. It lights too. so it’s not the bulb. Buzz one spade lug to drop light ground. Then the other. OK, the ground works. Buzz the other spade lug to the center contact in the drop light. Then flick the switch. OK, the hot works. Screw the bulb back in, wire dummy load directly to the radio. Press the Transmit button. Nothing. Increase to 50 Watts. Press the Transmit button. Nothing. “Oh, crap, my radio doesn’t transmit any more. Oh, crap”.

Something caused me to press down on the very-lightly-used straight key on the desk. The light bulb slowly grew brighter. The light bulb over my head slowly grew brighter. Reconnect the dummy load to the tuner outputs, reconnect the radio to the tuner inputs, key down again, and the relays clicked like mad. And the light bulb grew brighter still. So the Transmit button is useless in CW mode, though it works OK in RTTY and the sideband modes. And it’s not mentioned in the manual. I did RTFM!

Then I disconnected the dummy load, connected the antenna back up, and the antenna seems to tune right up on 160, though there’s nobody on that band as I write this.

I’ve made RTTY contacts on 20-meters, 40-meters, and 80-meters, though, so all seems right with the world.

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