New skywire

[altivo]

My antenna has been defective for months now. The feed line had broken loose from the radiating elements, making the whole thing useless. Last fall I ordered a commercial replacement, a somewhat better-constructed version of the same design, but when it came the bad weather had already set in. Lowering a 100 foot long antenna and raising a replacement in ice and snow... Well, it could be done of course, but I didn't need it that badly.

One of the things on my to-do list for this week was to finally get the old antenna down and the replacement up. Did that today. It turned out to be easier than I'd expected. In spite of the fact that the nylon ropes holding up the old one had been in place up in the trees for ten years, they still were strong and had not bound up in the bark so they slipped right down. We figured out how we had threaded the 102 feet of copper wire through the tree branches last time, and by using the old lines to pull the new ones into place, and then the new lines to raise the copper, we got it up there. The old one worked so well that I'm quite confident this will be great.

(For the radio geeks, it's a G5RV style doublet, full sized, with 450 ohm ladder line feed from an air-core coaxial balun. 102 feet on top, height above ground about 36 feet, orientation roughly NW-SE. I use a pi matching circuit for low power operation on HF, 80-10 meters. The orientation seems to help me work into Europe and the South Pacific easily, but Africa and Asia are not quite so good. And it won't sing on top band. I need to do something else for that.)

Now to replace the 2 meter vertical. I really need something for both 2 m. and 70 cm. And I've never had a 6 m. antenna at all...

Enough. There's a thunderstorm here, need to close stuff down.

Comments

[cabcat.livejournal.com]

Hey pony is there a good layout for a small radio transmitter aerial?

I have a little device so I can listen to what I like all around the house and outside :) The problem is the aerial has to be fiddled around with to get it to work.

[altivo.livejournal.com]

I'd need to know a lot more to make any suggestions. It depends on the frequency range being used, the power level, the receiver location and antenna... Transmitting antennas generally need to be adjusted pretty precisely in order to avoid damaging the transmitter or violating your local regulations about radio interference. While you can sometimes receive television or radio using a bent coat hanger wire for an antenna, trying to transmit with one would cause all kinds of havoc.

In other words, substituting a different antenna on an unlicensed transmitting device is probably illegal (it would be here, certainly) and may in fact damage the transmitter. Your best bet is probably moving the transmitter and/or antenna to find a better location for it.

[cabcat.livejournal.com]

The transmitter is a kit that is FCC approved, it's a low end frequency about 89mhz, the antenna on the kit is a piece of loose wire. The thing is usb powered and my brother made it for me. Unfortunately he also put it in an unshielded metal mint tin which I don't think is helping too much.

[altivo.livejournal.com]

All right, now I know what you have. It's one of those low powered FM transmitters that operate in the FM broadcast band. Those are extremely low powered. The antenna they provide is probably cut to the correct length for the frequency in use, but you'll find that the weak signal doesn't penetrate walls very well. Make sure that the transmitting antenna is stretched out full length and straight. Don't let it touch any metal, even though it is probably an insulated wire. It's best if you can suspend most of it in the air like a real antenna.

Beyond that, it's up to the receiver. Most receivers for broadcast stations don't have very good antennas themselves. You may be able to improve on that, depending on what you are using for reception. The same rules apply. Small personal receivers such as those that are built into MP3 players often use the earphone wire as their antenna, so fiddling with that wire may improve reception. It's likely to work best if you let it dangle loose rather than coiling it or tucking it into your belt or whatever. Switching to a different set of phones or earbuds may make a difference too.