Made a J-pole and getting KQRS out in the sticks!

Your tuner wants 75 ohm, that's why folks are suggesting you move the take off point up about a 1/2" and switch to new RG-6. Then all will be at 75 ohms

Nice job on the antenna and just in time as KQ has been playing great music on their album countdown this weekend.

I was reading this post to find more information about antennas and notice the OP and many repliers are from MN. KQ is a great station and it's good to see so many from the great state of MN

Well the J pole in this thread sure looks like the one I built and posted a long thread about here. I'm currently using Caroll 1108 50 ohm Coax as my lead in. The signal was tuned with that cable.

I used small water hose worm drive clamps to locate the leads attachement to the copper. I also cored mine with a fiberglass fence pole to make it much more ridgid then the 1/2" copper tube was alone. Mine is mounted at 18' above my house and 7' above a metal carport roof on one side.

I'm extremely happy with the results it being about to pull in even 12 watt GOD stations that are outside my signal area (the best one I can pull is 14 miles away on the other side of a hill taller then the transmission tower at a small baptist college)

Is there any "right" diameter and number of coils to make the best RF Filter?

Don't forget to ground the thing with some heavy gauge copper wire to an appropriate grounding rod. It is, in fact, a very good lightning rod as are all externally mounted antennas.

I'd like to revive this thread. I've been thinking that a good Omnidirectional FM antenna is something I want and this looks like a good one. But before I go out and build it I'd like some advice on a couple of points.

First, on the length of the antenna. According to the info in the J-pole handbook it works particularly well for frequencies above the design frequency. If this is true wouldn't it make sense to build it for 88MHz instead of 98MHz? Meaning the main pole would be about a foot longer.

Second, wouldn't it make sense to use the antenna mast as the ground rod and just attach the lower stub to that? In fact, why wouldn't it work just fine to clamp the 1/4 wave element to the side of a length of EMT conduit. slide it up to get the right 3/4 wave length for the long element and attach the lead? Seems like standard emt hanger clamps would work fine for that, and maybe a chunk of PVC pipe at the top for a spacer. Then use more lengths of EMT for additional height.

And why not use the alternate construction and put a coax connector on the bottom of the 1/4 wave element? That way a ready made cable would plug right on. Why not use common TV cable that is available everywhere and just use the matching connector?

JB

OK, well, sorry guys I couldn't wait around for you. Since I had some 1"x3" UHMW I cut a couple sticks on the radial saw to use for spacers, grabbed a couple stainess band clamps and threw together a quick prototype. Since the spacer between the uprights was 3" I built it for the 88mhz end of the spectrum and as it's easier to cut down than to lengthen it won't be hard to change if I need to. I put the feed line at 3-1/2", about 3/8" up from the calculated point of 3.120 to increase the impedence a bit over 50 ohms, and used the alternate construction with a chassis mount coax connector and adapter to TV cable. I put an EMT coupler at the top of the short mast with a short stub which can be used for tuning if I feel like it, but I probably won't. I hung a plastic cap over that to keep out water.

Standing it near vertical indoors and with a short cable and no balun, and no ground connection to the support leg it was unimpressive, no better than a short length of wire. But I have hopes for it and will get some coax, mount it to the end of the roof of my metal shop building and connect it using a 3 turn coax balun at the mast end and see what it does. Probably run some copper wire to a ground stake and let it pretend to be a lightning rod. So far my total investment has been about $10 or so for the coax connector and the adapter, not counting the other bits which I had on hand. If the ground plane of the tin roof creates any directionality it might be a little more effective in the direction of the nearest stations. Rural setting so no real concern over multipath.

JB

Finished. Definitely worth doing, my signal strength doubled. Better than a simple car antenna? Who knows? But it'll be just fine for what I need.

JB

Nice work. Height I've found height makes a huge difference with this type of antenna. Mine is still in my upstairs hallway. It works well but I still want to buy a rotator and directional yagi to mount on the roof.

I could easily go up another ten feet by just adding another length of conduit to it, but I think this will be just fine for now. It'll take me awhile to check out the stations that are available which weren't before. Probably the ground plane created by the tin roof helps quite a bit, and my heavy ground lead and ground rod directly below makes it a good lightning rod at the same time, something I was always a little concerned about.

I once had a rotator. It got left behind somewhere. If I was going to go that route again I think I'd want to look into one of those 3 legged towers that come in sections that you add to get more height, and then one of those big highly directional rigs. But for now it just isn't that much of a priority, I'm thrilled to get a signal strength of 4 on a local station.

JB

You used the same design I chose to provide a connector for the coax; mine's been on the sidelines since I put up the FM-6 and a rotator but it's just a matter of mounting it on a vent pipe and running some coax to a tuner in my electronics room. I'm curious to see if it'll pull in a couple of Canadian stations I use as an indicator for reception conditions.