First ever home brew antenna project....

[WX2MIG]

Over the years I've assembled many different factory made antennas, everything from the easiest...(Shakespear BigStick for 11 meters)....on up to Moon Raker beams and everything inbetween, but until today I have never actually built an antenna from scratch using non-specific materials to do it.....

To day I built a 2 meter J-Pole using the information provided in the ARRL Antenna Book, with a slight design change I got from a guy that sells them on eBay.

Laid everything out on the driveway.....

Using my Map Gas tourch, I soldered everything together.....

Mounted it up to my garage, and ran some RG 8/U coax to it....

And here is a close up of my design change. The ARRL book has you strip back the coax, and connect the leads to the tuning straps via brass bolts, nuts & washers. I didn't like that route as much as I liked using an SO-239 connector instead, so I bolted the base of the SO-239 to the tuning leg, and soldered a piece of #12 solid copper wire from the connector to the strap on the radiator (taller) leg.....

I also made an 8" choke coil in the feed line as per the ARRL instructions, and weather proofed all the neccessary parts in RTV sealant or Liquid Electric tape.

I'm waiting on a fellow HAM to drop off an SWR meter, so I can check and tune this thing, but so far I've been able to bring up most of the area repeaters with a full return signal using my 5 watt HT, and the one's I can't are the one's I couldn't before, and that may be because I don't have the proper squelch tones programed in for them.....

Once I get this thing tuned to the lowest possible SWR's, I'll tighten up the nuts & bolts on the tuning straps, and the U-bolts on the mast. I suppose the next move will be a full power 2 meter rig.....

 

[Sonwatcher]

Looks like you've done well !

 

[WX2MIG]

Thank you sir......


Here's a couple more photo's of the near finished product......

I should also add.....I got done just in time, it started to rain when I was cleaning up, and putting away the tools.....

 

[Highlander_821]

Once you get it tuned, make sure to put it up as high as possible. When operating on VHF/UHF, height is paramount.

 

[W5LZ]

And just to 'egg' you on a little... that 'J'-pole will work pretty good on '440 too. Makes a 'dual-bander' sound like a better deal, don't it?? 'Perfect' 440 antenna? Nope, but who cares, it works!
- 'Doc

 

[WX2MIG]

Once you get it tuned, make sure to put it up as high as possible. When operating on VHF/UHF, height is paramount.

It's as high as I can get it, if I go any higher I'll have to straighten out the choke coil cause I'm out of coax......

I made contact with a repeater that's approx 25 miles inland from here, it's inter connected in a system of 6m, 2m, and 70cm machines that cover South Eastern PA, and Southern New Jersey. Talked to an oldtimer that's about 40 miles up the coast, he couldn't believe I was on a 5 watt HT 25 miles from the closest repeater, said I was solid into the machine.
I'm hoping to make contact with someone mobile that can go to a simplex frequency and give me a better idea of how well it's doing......

that 'J'-pole will work pretty good on '440 too

I read that it makes a good 144/440 dual bander, but I'll be lucky if I can get a power supply and a cheap 2m in this shack let alone a dually.....(money is real tight at the moment).... Besides, there's far more 2m action around here than there is on the 440 band. There are a couple of repeaters up and running, and one has a Sunday night net, but for the most part everyone hangs on the 2m machines, so getting up on 440 just isn't a priority for me right now. Much like HF....down the road when I can afford it.....

 

[Robb]

I've just bought a Yaesu FT-8800R a month ago, and all I have is a Diamond mobile antenna for the car. I have procrastinated buying a 2m/440 base antenna because I am working on my CB and Ham setup still. I'd like to build a J-pole too! I have seen these J-poles online and I didn't know you can get them to talk on 440Mhz. Is it going to be resonant on 440Mhz? What design changes would be necessary to make that happen for the J-pole?
Doc? Anybody?
Thanks!
N2ITH - nice job! What was the toughest part of making it happen? Materials? Tuning? Mounting? Is there a better way to tune or align it so that a coax choke isn't necessary?

 

[W5LZ]

Rob,
No changes needed, 440 would be about the third harmonic of 2 meters. That means that while it certainly wouldn't be the 'best' solution, almost any 2 meter antenna will 'work' on 440 at least some. Try it and see.
- 'Doc

 

[WX2MIG]

Rob,
The thing was very easy to build, and I already had the copper pipe sitting around from my last home plumbing project, and most of the fittings too. I had to hit the hardware store for the two 3/4" & 1/2" copper clamps, and the #8 X 3/4" brass screws, nuts and washers. I bought extras of everything and have enough to build another if this one blows off the roof....(it would take one hell of a wind to blow this thing apart).....

 

[N9RZD]

NICE JOB !!!!!!!
another "COPPER CACTUS" on the ham radio range !!
i see you used 3/4 , that will give higher bandwidth ,
and i like the strap, -239 arrangement

last one i built , i didnt have that stuff
so i just peeled the coax back ,
found the spot with lowest vswr and soldered it in place
i used 3/4 , and its virtually flat across the entire 2mtr band

is that a roll of "STA_BRITE" I see ?
i use it everyday for refrigeration fittings and can tell you
that was a good choice , its not cheap , but you wont have
any corrosion ,
i used harris 15 silver stick solder on my last build,

be curious to hear what kind of standing wave
you get from it ,

GOOD JOB !!!

73

 

[WX2MIG]

be curious to hear what kind of standing wave
you get from it ,

GOOD JOB !!!

73

Right now the SWR's are not good, 3 to 1 + on the ham bands, but it's much lower on the VHF Marine band. I rechecked my measurements and found my final length on both verticals a 1/4 inch too short....but that's not a problem, I got plenty of copper pipe here, I'll just sweat out the two verticals, and replace them with one's the proper length tomorrow. What probably happened is, when I pushed everything together I didn't seat the verticals all the way into the fittings and cut them a hair too short. I never thought to remeasure before putting it up in the air.

A Rookie Mistake.......:blushing:

I've been running it on low to medium power, and I'm hitting machines I never thought I'd reach, once I get it straightened out, and run full power, I'll be able to work 10 different repeaters with a solid signal, and another 5 with a weak signal, so I'm not all that dissapointed with this project.

Weather permitting, I'll get the fix in on it tomorrow, and report back the outcome.

 

[Moleculo]

What probably happened is, when I pushed everything together I didn't seat the verticals all the way into the fittings and cut them a hair too short. I never thought to remeasure before putting it up in the air.

A Rookie Mistake.......:blushing:

LOL, It happens to all of us. Did you see my coil loaded dipole build that was supposed to have one segment for 40m? I wasn't thinking and cut the wire to the proper length....only to realize later that when I attached it to the coil all the necessary wraps had made it too short for 40m. It happens....

 

[Captain Kilowatt]

1/4 of an inch shouldn't make that drastic of a differance. I'll bet you will also have to change the feedpoint position as well. Of the couple J-poles I have made the feedpoint position was never "by the book". Experiment and have fun. That's what it's reall all about.

 

[mackmobile43]

just solder on another connector and cut to length.

 

[WX2MIG]

Well I'm at my wits end with this experiment, I built a second J-Pole from scratch, make absolutely certain my measurements were right on the money, made 50 trips up & down the ladder adjusting the damn thing, and just like the first one, it radiates almost flat up in the VHF Marine bands, but I just couldn't get those SWR's down on the 2m ham frequencies. The best this one will do is just under 3.1:1.....(the first one ran close to 4.1:1)......:headbang

I changed feed lines, raised it up another foot, changed out the jumper between the radio and meter, ran a ground wire from the antenna pole to a copper grounding spike that's 4 foot deep.....no matter what I try, or how many adjustments I make, I just can't the the SWR's down to a reasonable level......

Everyone I've talked to that built one of these antennas has gotten no more than 1.2:1, and most get 1.1:1 on them......I don't get it......
I get great signal reports, was even on a simplex net this evening, and on medium power I was pinning everyone's "S" meters, so the thing is working, but with a load of reflected power.......

Any thoughts....????