The Copper Cactus Super J-Pole Antenna

After I had passed the General Ham Exam, then the next month the Amateur Extra Exam, and Heidi had passed her Technician Exam, it was time to actually use our new radio privileges. I had previously purchased a couple of, relatively inexpensive, Baofeng handheld radios and learned to program then, primarily with the CHIRP program, (which is another story). Those little HTs work quite well when out and about, walking, etc., however our own security camera system I had installed some time ago interfered with reception in our living room.

By this time, we were enjoying checking in on the our club’s “Donut Net” each Monday evening at 7 PM, but it was kind of cramped for both of us to cram into the little “Ham Shack” to do so – and I determined we needed to put up another 2 meter antenna, running the coax into our living room, so we could enjoy UHF and VHF operation from the relative comfort of our couch and/or love seat.

I spoke to our friends, (the Amateur Extra’s who live up in the community of Crest, CA), and they both suggested a Copper Cactus Super J-Pole, which is what they use – not only that, but if we would come on up, they would help us build it! (Offer you can’t refuse?) After a lot of experimentation with various j-pole designs, they homed in on one that was based on 3/4″ copper tubing. Most are constructed from 1/2″ tubing, but theirs seemed to be more wide-banded and worked very efficiently.  I had seen theirs on previous visits and was very intrigued, not only with the design – but how the heck to put it together?

Our friends already had most of the materials, and as they had previously built about 10 of these – *all* of the equipment and know-how.  All 4 of us gathered in their garage and it was a fascinating experience!  Each of us had a hand in the soldering and construction. When we returned home I couldn’t wait to get it mounted.  Took down an old Archer vertical antenna I had cut down for 10 meter operation over 10 years ago – and put the j-pole up in its place on the previously installed chimney mount, running new coax into our living room.

Tuning is accomplished on this one by simply moving the feed point. Ours is a flat match for both UHF and VHF. The looped co-ax serves as an "air-core balun".

Tuning is accomplished on this one by simply moving the feed point. Ours is a flat match for both UHF and VHF. The looped co-ax serves as an “air-core balun”.

 

The copper cactus design we constructed is a dual band antenna – works for both 2 meter and 440 MHz – that copper loop serves as a kind of coupler/isolator between the two sections of vertical antenna.

 

Installing a rather tall antenna by yourself is challenging, fortunately I have very strong hands, even at this age.

Installing a rather tall antenna by yourself is challenging, fortunately I have very strong hands, even at this age.

 

The copper will darken and weather over time, so it will not be quite as "visible".

The copper will darken and weather over time, so it will not be quite as “visible”.

Our home is South-facing, so the lion’s share of our solar panels are on that side of the roof.  Had to be very careful up there not to slip and damage anything inadvertently. 😉 The end result of our day’s endeavors were nothing short of excellent. We can literally use any repeater in the area we wish to.  Generally we are found on the ARCEC 2m repeater though.  Its kind of like “home” for us these days.

Initially, I used an adapter cable and simply plugged it into one of the little Baofeng HTs, but you get what you pay for, and putting a stronger antenna to them opens up that receiver to interference from any strong signal nearby.  In April, 2016, I replaced the Baofeng with a little Yeasu FT-60R which has a much better receiver and the ability to protect itself and most of the interference immediately went away.  Life is good!

This entry was posted by dave on Sunday, May 8th, 2016 at 11:39 pm and is filed under Amateur Radio, General Ham Stuff . You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

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