http://www.ebay.com/itm/Dual-Band-VH...item1c2e7e7976
Dumb question: if you touch this during tx, would you get burned?
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http://www.ebay.com/itm/Dual-Band-VH...item1c2e7e7976
Dumb question: if you touch this during tx, would you get burned?
I wouldn't buy one, too much of a compromise. It's easy to make your own VHF antennas out of copper pipe or whatnot. And, yes, if the transmitter is powerful enough, you could get an RF burn if you touch any antenna while transmitting. The voltage at the ends of an HF dipole fed by a 100 watt transmitter can exceed 3000V.
OK, I thought that might be the case. So when people put dipoles in their attics is that not a fire hazard?
You just have to be careful to have good insulators at the ends is all.Quote:
Originally Posted by EightGodzillas
How's your fabrication skills? Can you solder? Have access to tools? Are you eager to learn? Do you follow written instruction well?
Answer all of my questions please.
Yes, if you touch it, you could get burned, as low as 25W. By and large, you don't get antenna's causing fires in attics, because the wood is dry, and a good insulator when dry. However, the addition of some sort of standoff helps too. Your hand contains lots of water, and is a pretty good conductor, compared.
FWIW, I've had a VHF antenna touching the beams in the attic, with no effect, but safety with standoffs is a cheap insurance.
As for your antenna you located, I'd skip it. It's hard to see how to make a UHF/VHF all-in-one vertical work well enough to just not make your own. I'd start with a simple 1/4w groundplane to start with: East to make, should take you less than 20 minutes to do: http://www.movl.net/blog/2009/03/my-...plane-antenna/
Attachment 8299Quote:
Originally Posted by KJ6BSO
Or, keep your power under 100 KW. ;)
If you touch the wrong spot your finger will get burned, if you buy it your wallet will get burned. J-poles come in two flavors, copper and twin lead, copper is too wide at the bottom to fit into that diameter PVC and the PVC isn't supplied so guess what you're buying.
Here's the skinny on a J-pole vs. a ground plane, it's all in the vertical takeoff angle. A ground plane has a main lobe at 45 degrees while the J-pole's half wave radiator (the part above the U shaped matching section) has a lower angle so it exhibits some gain over the ground plane. Look at it as an end fed vertical dipole and you can easily visualize the radiation angle.
Another question to ask yourself.....good for what? What's the intended use? If you're in a repeater dense area, sure, it'll probably get you there. Where I'm at, not so much...the closest repeater is about 50 miles away. Don't think moonbounce, either.
Yes, I am pretty decent at making things if I have the tools. I can solder. I have a tool box. I earned a BS and a BA by the time I was 20, so I am eager to learn. I also like making my own over buying something.Quote:
Originally Posted by KA9MOT
I like board games, holding hands, long walks on the beach and snuggling. You look like a snuggler. I spoon to the right.