J-Pole Antenna

rover67 · Dec 24, 2010

I kinda want an Arrow Yagi now.

nakman · Dec 29, 2010

KD0MZE and I got a few QSO's in last night with the J-Pole.. I was running 1 watt from my VX-3r HT, using a ridiculously long length of coax. Nothing revolutionary, caught a couple guys on the 145.310 repeater who both said our signal was nice and clear. Good to go!

rover67 · Dec 29, 2010

Grr....

I wonder what the hell is up with my crap then.

I must really be in a bad spot... I still haven't done the 100Hz tone thing..

CardinalFJ60 · Dec 29, 2010

I was impressed...

so impressed, I got online and bought the arrow jpole last night. Not only was there a mile of coax, the antenna was on the ground (vertical of course). the RX was clear as a bell. Waaaay cool.

nakman · Dec 29, 2010

rover67 said:
Grr....

I wonder what the hell is up with my crap then.

I must really be in a bad spot... I still haven't done the 100Hz tone thing..

I'll bring this over to your house some time... if it can hit the .310 and your crap can't, well there you go we've isolated the issue..

rover67 · Dec 29, 2010

nakman said:
I'll bring this over to your house some time... if it can hit the .310 and your crap can't, well there you go we've isolated the issue..

good idea

or maybe i need a :yagi:

CardinalFJ60 · Dec 30, 2010

That 100hz tone works!

I was messin' with my new HT last night and hit K0NAK from my living room on .310/123hz but scratchy....then he suggested the other tone. worlds better. That might just be your ticket. BTW...UPS is showing up today with my Arrow antenna.

rover67 · Dec 30, 2010

Here's whats funny, I checked what tone my radio was set to on the 145.310 repeater and it was actually set at 100Hz..... So I thought I was done for. I changed it to 123Hz just for kicks and I was actually able to hit the repeater and talk to K0NAK so I consider it a total success.

I guess a while back I figured out about the 100Hz thing and changed it when I was trying to hit the repeater with the bigger diamond antenna (HT Mounted)and just forgot about it.

Anyways, this was all still with my home made J-Pole stuck in the fence in the back yard. Mission accomplished I think.... Tim did let me borrow his new Arrow J-Pole so I am going to do a little comparison of the two later.

rover67 · Jan 4, 2011

Well I have to say I am pleased!!! I was able to talk to KC0PEG on his way home and try out both the arrow J-Pole and my Plumbers special J-Pole.... from what Dave said the Plumbers special was as good if not maybe a touch better than the Arrow!!

Sweet!!

I am stoked that it works as well as the Arrow, and that I can talk on the CCON from the kitchen! Mission accomplished! Maybe now to make a Yagi!

rover67 · Jan 6, 2011

Pics

pics of the antenna!

I need some input here.... do you HAM guys thing it would be OK to put a threaded joint like I did for the bottom part on the main part of the antenna to make it break down a little bit more? My only concerns are that the threaded portion is tapered so over time the overall length of the radiating element may get a bit shorter.... that and maybe the union is not cylindrical so maybe it'd make it radiate funky.

What do you guys think?

EDIT: I just reread my thread and realized that this was one of the first questions I asked!!! Sorry!

xodeuce · Jan 8, 2011

rover67 said:
pics of the antenna!

I need some input here.... do you HAM guys thing it would be OK to put a threaded joint like I did for the bottom part on the main part of the antenna to make it break down a little bit more? My only concerns are that the threaded portion is tapered so over time the overall length of the radiating element may get a bit shorter.... that and maybe the union is not cylindrical so maybe it'd make it radiate funky.

What do you guys think?

EDIT: I just reread my thread and realized that this was one of the first questions I asked!!! Sorry!

The length of pipe below the T fitting doesn't matter. It can be short, or you can U-Bolt it to a metal mast which would make it electrically much longer. The radiating element is wholly contained above the T as I understand it. I think if you're DC grounded below the T, you need a balun to keep the coax from radiating. Something like 4-5 turns of coax around a PVC pipe at the feed point of the antenna.

-Keith

Seldom Seen · Jan 8, 2011

rover67 said:
pics of the antenna!

I need some input here.... do you HAM guys thing it would be OK to put a threaded joint like I did for the bottom part on the main part of the antenna to make it break down a little bit more? My only concerns are that the threaded portion is tapered so over time the overall length of the radiating element may get a bit shorter.... that and maybe the union is not cylindrical so maybe it'd make it radiate funky.

What do you guys think?

I wouldn't over think it, just do it. The copper cactus is much more broad banded than its twin lead counterparts. Slight differences in OAL and diameter aren't going to make big changes in its resonance.

Choke baluns are never a bad idea, I like to use ferrite snap on beads (mix 43 iirc)

rover67 · Jan 8, 2011

I coiled the coax about 5 times near the connector.

I'll look for a ferrite snap on thinggie!

Thanks for the feedback! and it's nice to see you on here Keith!

xodeuce · Jan 9, 2011

rover67 said:
I coiled the coax about 5 times near the connector.

I'll look for a ferrite snap on thinggie!

Thanks for the feedback! and it's nice to see you on here Keith!

I've been lurking around your FJ40 resto page for a while. Figured I'd finally go ahead and join.

Good looking antenna you built there. We just started a 2M simplex net in B'ham, and it's got me wanting to get something outside and up high.

CO Hunter · Jan 9, 2011

Slight differences in OAL and diameter aren't going to make big changes in its resonance. [/QUOTE said:
FWIW, during construction of mine we put in a small screw on the short end to fine tune the copper j-pole. Additionally, the number of coax coils, diameter and location/orientation at the bottom of the "J" made differences in the impedance. We tuned it for the center of the 2-m band at 50 ohms. Antenna analyzer was MFJ-259B, I believe. Unfortunately I don't remember the ranges of these changes but I do remember the differences were enough for us to pursue changes.

jacdaw · Jan 9, 2011

DaveInDenver said:
The Broomfield machine is 145.310-, 100Hz tone. It's a RX-only for the system, so if your shadow causes your reception to be scratchy then it won't help (it does not retransmit 145.310, just listens to 144.710). It's job is to help primarily Boulder hams when they TX to get into the machine.

Does 531 have multiple voting receivers?

nakman · Jan 9, 2011

Marco, that antenna sounds 10x better on simplex than it does the repeater.. nice work, man, better than a soup can on a string, that's for sure.

bvb · Jan 9, 2011

Got my arrow 70cm/2m up today, hooked the FT60 to it and wow! I can hit the repeaters and simplex seem to be much better signal. Low power gets in to the repeater with no problem. Ready for the weather to turn and make us have to hang around the house and monitor the radio. :beer:

CardinalFJ60 · Jan 9, 2011

I agree!

I was messin' around with my new arrow setup and it is nice to have a decent antenna on an HT. sounds quite good...I made contact with KD0NIC on the connection on Saturday.

nakman · Jan 9, 2011

Hey Shawn are you messing with it tonight? let me know if you want to try simplex.. send me a text or something.

J-Pole Antenna

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