146.5 MHz 2 Meter J-Pole
I like J-poles, and slim-jim antennas for verticals, NO radials needed, excellent performance, & easy to build!
No need for detailed instructions, these pictures tell a thousand words, need help? email me! Some people
use aluminum or copper pipe, I had 1/2" EMT rigid conduit, a bit heavier but should last forever! For 146.5 MHz,
cut the element to 57.72". The shorter "tuning stub should be cut at 19.2".
Close-up of my S0239 Connector assembly and rain-caps. I like using that liquid rubber stuff to weather-proof things!
Closeup of how I mounted the pipes to the angle iron support. I do not weld! This worked just as well for me!
Better view of angle iron support and how I secured the pipes::
Closeup of the little "separator" I made from PVC pipe to keep the tuning stuff at the correct spacing even during tornadic winds,. Well perhaps not that violent!
Here she is so far. Just need to connect the S0239, get her in the air and do some tuning!
Moving right along, last night I put the J-Pole in the air about 13 feet, on a temp basis to tune it up and mark the locations for the S0239 connector in order to get best SWR. Here is a photo of the connection I made: Photo is during daylight of course!
You will want to add an Air-Choke to keep RF from coming back to the radio room. This also helps get better SWR readings! I find that 5-7 widings of coax on a 2" to 5" PVC pipe form does the job very well!
Before I forget, while tuning I had to add about a 5" extension to the main element in order to get the SWR I wanted! It's rare you will ever get perfect SWR using an antenna caculator, you will always need to cut or extend the element or tuning stub a bit to get the SWR where you want it. I'm picky: At first I had 1.6 at 25 watts, 2.1 at 60 watts. I knew I could do better, so adding this 5" extension after a bit of trail and error I got the swr down to 1.2 at 25W, 1.3 and 60W!
Finished product, although I will mount it properly and at about 25 feet in the next few days. Works great! Cost about $5.00!
Here is a GREAT J-Pole Caculator that I used for my measurments! Can also make them for other bands!
Making your own antennas is fun and inexpensive! Nothing like talking around the world with an antennas that "YOU" built!
73,
Dave Verticals / Etc.
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