300 Ohm J-Pole 1

300 Ohm Twin Lead J-Pole Antenna

Here is a J-Pole antenna that I built back in November of ’09. This build was taken from QST, September 1994. The author is Jim Reynante, KD6GLF. A PDF of the file can be found at the bottom. I am not going to go into how I made it. You can read that for yourself. What I am going to do is offer my notes and photos on this antenna.

This is my primary antenna when I am at home. It is hanging from the ceiling of my dinning room by a planters hook. I can hit the local repeater which is about 5 miles away with no problem. I need to use low power to hit the repeater, about .3 watts.

I can also hit a repeater out side of the county about 18 miles away with this antenna. But I need to increase the power to 5 watt. I have not really tried getting into many repeaters other then the two. I guess I should do a range test to see how far I can get with this antenna.

Now for my notes and comments on this antenna. If you are new to amateur radio I would not recommend this antenna. It was a pain to build. I had to make this antenna 5 times before getting it right.

The parts for this antenna can still be found locally. All you need is 300 Ohms twin lead wire, some coaxial cable, soldering iron, SWR meter and a lot of time for a new ham. The problem with this antenna is that for a new ham you need a SWR meter to tune it. If you don’t have one then you need to find someone that can help you with that. It was not easy to tune for someone like me being only in the amateur radio field for about a month.

I also had a problem with the coaxial cable. I purchased 50 feet of RG-58U with BNC connectors on both ends for $10. Now if I just would have use it as is there would have been no problem with this cable. But when I cut it and tried too solder the braid to the antenna it would not hold any solder at all. I had to introduce a small copper wire into the braid for it to take the solder. So if you do plan on making this antenna make sure you get good coaxial cable.

This is a great antenna if you want to give it a try. I was able to get it to work but it did take some time. I plan on making a new j-pole with a different balun type. One with a toroid that will allow the antenna to go into a PVC pipe so that I can put it out side.

Update – August 14, 2010
I have put this antenna into the go kit of the Yaesu VX-6. This makes a great emergency antenna. It rolls up and fits into the bag with no problem. Make sure you don’t roll it up to tight. I have created a new j-pole antenna for use with the ICOM 2200h and have also added it into its go kit. This new antenna has a 1:1 toroid balun and a SO-239 connector.

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