Monday, November 2, 2009
The Slinky J-Pole?
When my Dad and I were playing with the slinky Buddipole, we started to talk about other possibilities. We talked about doing a j-pole for HF with regular size Slinky's. I have a j-pole that Ed Fong (WB6IQN) made for me off his design and article in QST. It works great for 2 meters and 440. I have that j-pole inside my chimney at the top of my house so no one can see it. From here I can hit repeaters in Arlington, Ft. Worth, Denton, Waxahachie, and even Commerce Texas. I had plenty of Slinky's so why not give it a try. I found this really good j-pole calculator (http://www.hamuniverse.com/jpole.html) and figured that it might be possible. Since a 40 meter j-pole would require a long side of almost 100 feet of wire, why wouldn't a slinky work since one slinky is 65 feet of wire. So off I went to Lowe's and Home Depot to find materials. PVC is easy to work with, but is really wobbly the taller you make it. I found some electrical conduit PVC pipe that was 1.5" in diameter. I picked this type because it had a built in coupler to join another piece. The 1.5" by 10' pipe should be sturdy enough for one 20' pole. I also found a 6' piece of re-barb. These three pieces cost me $7. I put the re-barb into the ground about 18"-24" and slipped the PVC over it. To my surprise, it did not tip over as I was sure it would. I tried to knock it over but is stayed up right. Must be the hard clay we have in the ground in Rockwall. I tried once to put a 20'-25' PVC pole up using 3/4" and 1" pipe, it would not stay up. I used what I already had in 1" pvc to make the short side of the j-pole at 10'. I joined two Slinky's together for the 20' pole and just one on the 10' pole. I heard several stations on 40 meters which I thought was a good sign since it was during the week and during the day. I heard a CQ from WA4PUB in Marietta Georgia. He and I talked for several minutes. So yes this antenna works. This is a quick set up and really cheap to make. This antenna would be great for Field Day or just hanging out in the back yard on a nice Saturday afternoon. Without modifying this antenna for 20 meters, I heard several stations as well, including one in Hawaii, Ecuador, and Chile. A 20 meter j-pole would be easier than 40 meters since it is about half the height on both legs. Next is to try this antenna at our club outing this Saturday. RARC's first Ham Radio in the Park. Should be really nice weather and a good time. Can't wait to try this antenna there.
The cost of the items for this antenna (40 meters):
3 Slinky's at $2.99 each at Target
3 10' PVC or PVC electrical conduit at $2.70 each
2 6' re-barb at $1.30 each
Total is about $20
Posted by Johnson at 4:43 PM