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-   -   J-Pole Antenna (http://www.risingsun4x4club.org/forum2/showthread.php?t=14722)

rover67 12-17-2010 02:25 PM

J-Pole Antenna
 
I want an antenna for the garage and for camp that will extend the range of my VX-7R. Right now with the mag mount antenna on a pie plate I can't hit Colorado Connection from my house in Boulder. That's kinda crummy.

When I met Kurt in the Swell for the Overnighter I noticed he was using a J-Pole, so that got me thinking... I need one to. It seemed to work well. I have a pine tree outside the garage I want to put it in.

So I dug a little bit and found these instructions:

http://www.alpharubicon.com/elect/jpolejaden.htm

A few questions....

Can I add a threaded connection in the main mast (halfway up section "a") that I can take it apart at? I seem to remember that Kurt Had his put together like that.

Also, what coax should I use? Seems like there are a ton of options out there.

Seldom Seen 12-17-2010 02:58 PM

Quote:

Originally Posted by rover67 (Post 170530)
A few questions....

Can I add a threaded connection in the main mast (halfway up section "a") that I can take it apart at? I seem to remember that Kurt Had his put together like that.

Also, what coax should I use? Seems like there are a ton of options out there.

Yes you can put a threaded coupling in the long element for easier transport.

For a portable setup I'd use the shortest run of 8X coax as possible. 8X is the same OD as RG58 and but is more flexible, plus it has less loss at V/UHF. 8x ain't perfect, but it will certainly get the job done.

With the price of copper these days (unless you have some laying around) and the time building and tuning, I'd put my money down on another one of These. Plug and play, no tuning and it gives you 440 which opens up 100's more repeaters. You can even order it with a threaded joint in the long element.

Edit: looks like Dave beat me to it on the coax. The 310 machine is above Golden just outside Golden Gate State Park.

nakman 12-17-2010 03:10 PM

your 145.145 repeater is the Squaw Mountain one, eh.

and the 145.310 should be completely reachable from Marco's house in Boulder, I don't think there's a shadow.. I can hit it easily from the mobile rig in the truck so HT+J-Pole should definitely do it, IMO. :beer:

Bruce Miller 12-17-2010 04:31 PM

Arrow Antennas
 
I use the Arrow Antenna Model 146-4S, a 4 element 2 meter beam. Arrow Antennas are built in Cheyenne. The workmanship is excellent and the prices are very reasonable. The assembly directions are good and they offer a full, no hassle refund. The owner at Arrow is an excellent machinist with old fashion values. I highly recommend any of their products.

Convert 12-18-2010 07:51 AM

x3 on the Arrow j pole been using mine for a couple of years now

CO Hunter 12-18-2010 08:18 AM

Homebrew
 
For me and my son the fun was in building them, especially as new HAMs. We made j-poles from copper as well as some twin lead, both work well. Both seem to work on 440 as well, but we have not done extensive testing. However, having a friend with a good antenna analyzer is important for proper tuning.

smslavin 12-18-2010 09:04 AM

Quote:

Originally Posted by DaveInDenver (Post 170575)
FWIW, if anyone is ever interested in tinkering, please do not hesitate to drop me a line and I'd be happy to do what I can.

I may do that once we move, if that's okay. I'm reading a lot but theory only takes you so far.

rover67 12-18-2010 03:44 PM

Well, I threw the first one together last night. It cost about $15 for the copper from home depot. The Arrow ones sure look nice, I kind-of think I could just get one of those for $35 and call it a day. On the other hand, I feel like making another J-Pole with copper from the depot and having it be the one I take places.

I still need to play with the antenna to see if it works, haven't really had a chance yet.

Oh, and I did end up getting the 8X coax... the guys at HRO pointed me in that direction. I was torn between that stuff and something else a bit thicker that they said was really nice. The guys at HRO were really a hoot to talk to. I stuck around there for about 20 minutes just chatting with them.

But dang, those arrow ones look nice...

rover67 12-18-2010 09:10 PM

OK, tonight I put the second one together... I was a lot more careful with this one and got all the lengths as perfect as I could for 146.460.

I noticed I soldered the connector on the old antenna backwards... the shield to the main element. Also, for the new one I used electrical solder and flux. one of the websites said not to use plumbing stuff since it does not work well when an electrical current passes through it.

I also noticed that I didn't have the CTCSS tone set right on my vx-7r. I set it right and was able to get the 145.310 CCON repeater to work from my house. The smaller HT mounted antennas still didn't work, but again the J-Pole allowed me to at least get the repeater to respond when I "kerchunked". Tomorrow I'll key up and try to see what the signal strength going into it is by trying to transmit.

Hulk 12-20-2010 10:20 PM

I have the Arrow Antenna J-Pole mounted on the back of my house. I can talk to folks all over the front range on simplex with it, and our house is in a valley.

When I mounted it, I had a few questions about grounding and called the guys up at Arrow Antenna. They answered the phone and talked to me -- you can't beat talking with an expert!


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