Murphy's Law made an appearance earlier today while I worked in the July heat on my broken dipole, but fortunately, it didn't thwart my efforts. Success!
The dipole itself was in fine shape; I've repaired it a three or four times in the six or eight years its been up in the air, and it looked fine. It looks like something snagged the feedline and it broke off cleanly at the center insulator at the bottom of the strain relief. Perhaps it was just time and movement that wore through the insulation and the wiring that led to it breaking.
The feedline is 300-ohn TV twinlead that I bought at the Indianapolis hamfest about 10 years ago. I bought a large spool of it, several hundred feet, and I've used it for Field Day antennas over the years. In fact, this antenna was originally a Field Day antenna. The twin lead has held up well in the sun and elements.
Lowering the antenna was a trick. One end of the antenna tie-off is tied to a small maple tree, and the supporting rope has been “captured” by the tree and grown around it enough to make it impossible to remove without carving away the tree bark. I untied the other end and had Elijah pull the antenna toward the far end. The antenna goes over a redbud tree, and I was unable to “walk” the antenna out of the tree due to the way everything was laid out. The simplest solution was to simply pull enough slack to allow the center of the antenna to drop low enough to the ground to grab the antenna — without pulling the entire thing out of the tree. Fortunately there was plenty of support rope on the center and far end to allow me to do this.
Once I had the center down, it was time to reattach the feedline. The solder joints are old, and trying to resolder weathered solder joints is a pain. I had a high-wattage soldering gun, but it was hot enough; the antenna wire and the existing solder joints needed more heat. I broke out my torch (after finding all the parts) and that provided enough heat to get everything soldered. Once that was done, we raised it back up and congratulated ourselves on repairing the antenna without breaking anything else in the process.
The repaired antenna plays very well … in fact, I suspect one leg of the twin lead had been broken for some time before the other one broke. I suppose this makes a good argument to drop your dipole annually and inspect it for damage. Had this happened with 3 feet of snow on the ground, it wouldn't have been this easy!
* * *
In other shack news, I just wrapped up one of the mods for the Radio Shack DX-394 HF receiver. This one was a very simple one that eliminates the “chuffing” sound when tuning. Wow, did it improve the “feel” of the receiver! The mod was to remove a wire from a molex connector; I removed it and did not clip it, I figured the mod is reversible that way … though I'm not sure why someone would prefer the chuffing.
I received the parts I ordered to do the next mod — this one improves the receive audio, an involves swapping out some capacitors. Not sure when I'll do that one, but hopefully soon.
The next mod will address the noise blanker and the SSB received audio, and both are simple. The noise blanker involves adding a Schottky diode, and the SSB audio involves swapping out a bypass capacitor to attenuate audio lower than 300 Hz.
There are some additional simple mods that address some other issues — power supply hum, and additional noise blanker improvements, etc. — but these involve adding surface-mount components, and I don't have the equipment to take care of those components.
I'm not sure yet where I'll be listening to the DX-394 … I tried it on the desk tonight after the anti-chuffing mod, hooked to my dipole through the tuner, and the signal strengths and intelligibility were pretty good. The receive audio still stinks in comparison to a ham rig, so we'll see how the mods help. With all the mods, the receiver gets very high marks for its performance; that's all well and good, but I'm not interested in spending big bucks on a bargain-price receiver.
I'll do the mods I'm comfortable with, and then see where to go. One thing I haven't tried but may is to use that Radio Shack DSP unit with the receiver. It may help, but there's one rule of ham radio gear I will never be able to escape — you can't polish a turd.