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.
:rofl:Quote:
Originally Posted by EightGodzillas
I want to DX, mostly. I think I said that right. I want to learn code. I want to try eme. I want to warn people about the Zombocalypse when it happens.
Hey! That's zombie apocalypse, station! Get it right...:):lol:Quote:
Originally Posted by EightGodzillas
Signed.
Ham radio speech police.
This guy is going to do well here on the Island.Quote:
Originally Posted by EightGodzillas
Then homebrew it is!Quote:
Originally Posted by EightGodzillas
When I was a new ham my first antenna was this: http://www.movl.net/blog/2009/03/my-...plane-antenna/
It looked terrible but it worked like gangbusters. It also worked on 70cm (440)
My next antenna was this: http://www.kf7ote.com/2011/05/our-ne...en-stub-j.html It is a dead copy of the Arrow Dual Band J-Pole http://www.arrowantennas.com/osj/j-pole.html . 2 things on this antenna. It works amazingly well. It is tough. I had mine attached to the right mirror on my Pete when I was trucking and hit an owl or hawk with it @ 80 MPH. It damn near took the mirror off but it didn't hurt that antenna any. http://www.eham.net/reviews/detail/1613
If you want to post your email or PM it to me I will send you the plans for a very good homebrew 5 element Yagi.
Now, let's talk about that cuddle, can I bring my wife? She's gonna want to play too...... :lol:
For $20, or so, you can get all the parts you need from Home Depot or Lowes to build a "copper cactus" J-Pole antenna for 2 meters.
For a heck of a lot less, you can build 1/4 ground planes for both 2 and 440 -- using an SO-239 connector and a coat hanger.
From what I've seen of the specs, this is a J-Pole made out of twin lead (they're available online, just search.. for example, http://www.rollanet.org/~rrars/tech_files/ select the '300 Ohm Twinlead dual band Jpole .PDF file). Nothing you can't do on your own.
But this antenna will only give you local V/UHF coverage. No HF. Certainly no DX.
I don't expect it will have much impact on the zombies, either.
Speaking of building antennas, what kind of PVC do you think works best, the electrical or the schedule 40 water stuff?
I'm thinking the gray stuff would be more UV resistant.
Neither.Quote:
Originally Posted by KB3ZGV
One of my homebrew 2 meter favorites. Suspend it inside a PVC pipe if you want a "stick" style antenna.
Can also be hung up high in trees, and it almost disappears...
http://larc.hamgate.net/pocketJpole.htm
http://larc.hamgate.net/300ohmJ-Pole.gif
LARC's site has some good infos :)Quote:
Originally Posted by WØTKX