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 Post subject: Copper Cactus 2m J-pole
PostPosted: Sun Oct 28, 2007 6:41 pm 
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I made a simple 2-meter j-pole antenna out of copper pipe this weekend, to see if I could coax some range out of my poor little shitty borrowed Yaesu HT FT-23.

It cost me a grand total of $18 in parts, and took about 4 hours to build and tune. I bought the parts at the hardware store, and needed the following tools/materials in addition to what went into the antenna:

I know everyone who reads this forum has all this shit at home, but I'll mention it anyway.


Blowtorch
Solder
Acid flux and brush
Screwdriver
Soldering Iron
Hacksaw or Dremel
Miscellaneous screws
Copper pipe mounting clamps/straps
SWR Meter

I followed the directions I found here (NOTE: hey holy shit I didnt realize until just now that was an Alpha Rubicon URL)
and constructed this:

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It tuned up with a 1.05 SWR (Fuck yeah!) which I'm going to file under "good enough for shit I made from scratch".

It's sitting in my garage, as high as I can get it. I figure this is the best compromise I can make, since I dont want to deal with an exterior antenna, and the garage roof is uninsulated and offers minimal resistance.
The math I did says that the tip of this antenna is at 615 feet above sea level, which shouldnt matter too much for 2m I guess, but its as tall as I can get it. Anyway, thats my antenna.

NOTE: 2m sucks when you live out in St. Charles. A HT wont cut it, get a mobile.

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Double note: 1.05, bitches!!!! Thats better than the mobile antenna I bought yesterday :D :D :D

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PostPosted: Sun Oct 28, 2007 6:56 pm 
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Nice. I love j-poles.

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PostPosted: Sun Oct 28, 2007 6:56 pm 
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Sweet! Did you make any contacts on your HT yet?
Also, I scored about 100 ft of twin lead for $5 if you want some.

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PostPosted: Sun Oct 28, 2007 8:36 pm 
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No, no contacts on the HT AT ALL. Even when I try local St. Charles repeaters I cant hit shit. I actually took that antenna up to the top of the biggest hill around and got on the local 2m repeater to ask if anyone could help me with an equipment check. Either I sound like a dick on the radio and no one wants to help (possible) :D, or no one was listening on a sunday afternoon (unlikely), or my borrowed HT is actually not working right.

Still though, I could receive a lot stronger than I could before.

EDIT: Let me figure out how to make a couple baluns and I might be able to use that twinlead to get a signal down to my basement. What I really need is a big roll of RG-8X


EDIT 2: Hahah fucking shit. My borrowed HT has a bad mic, it seems. I guess thats why I havent made any contacts for a month straight, trying every night.

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 Post subject:
PostPosted: Thu Nov 08, 2007 8:21 pm 
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Hahaha, well I solved the mystery of the HT, the damned mic was bad, so no one could hear me. It was frustrating, because the repeaters would all activate when I keyed up, so I had no idea I wasnt being heard.

Oh, well.

I got a new HT, and can hit almost everything. Using 5 watts, I'm easily readable on a repeater 20 miles away, which is offically good enough for me.

This antenna kicks some ass. I cant wait to see what a 50W mobile does.

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PostPosted: Thu May 22, 2008 1:42 am 
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Bumping this for informational purposes...

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PostPosted: Thu May 22, 2008 9:27 am 
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I still love this antenna. I'm in St. Charles, and can get to mid-town repeaters that are almost a half-hour drive away on 5W. It's absolutely bombproof too, I mean hell, soldered copper pipe isnt going anywhere, ever.

If you want some information about construction techniques or run into any gotchas, make sure to let me know, I'll help out however I can.

My overwhelming advice is to clean the copper ends before you start soldering. Use sandpaper or a scotchbrite pad, and make sure to use the acid flux. If you've ever sweated a copper joint, you can do this. It's the same thing.

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PostPosted: Thu May 22, 2008 11:36 am 
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crypto wrote:
I still love this antenna. I'm in St. Charles, and can get to mid-town repeaters that are almost a half-hour drive away on 5W. It's absolutely bombproof too, I mean hell, soldered copper pipe isnt going anywhere, ever.

If you want some information about construction techniques or run into any gotchas, make sure to let me know, I'll help out however I can.

My overwhelming advice is to clean the copper ends before you start soldering. Use sandpaper or a scotchbrite pad, and make sure to use the acid flux. If you've ever sweated a copper joint, you can do this. It's the same thing.


When I make this, it will be my first attempt at any sort of soldering of metal. Closest I've come to doing anything like this is building potato cannons.

Another question... I know this is a 2m antenna but when I was reading on the link you posted he said it was made for 146mhz does it just work on that freq. or does it work all across the 2m band?

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PostPosted: Thu May 22, 2008 11:46 am 
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any antenna will have a frequency where it is most efficient, and then it's efficiency and sensitivity will fall off in either direction from that number. 146 is square in the middle of the 2m band, and so this covers the whole thing excellently.

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PostPosted: Thu May 22, 2008 12:25 pm 
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Awesome... thanks.

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PostPosted: Thu May 22, 2008 11:25 pm 
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IllicitDreams wrote:
When I make this, it will be my first attempt at any sort of soldering of metal. Closest I've come to doing anything like this is building potato cannons.


It's actually not that different than building a potato cannon! :D

1.05 is *excellent* SWR, as you say, it's better than some professionally made antennas. Good on ya, crypto!

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