Just built a J-pole antenna-WOW!

Stumbled across the plans to build one while reading up on ways to improve/increase FM reception. I basically built this one:

http://latham.dropbear.id.au/antenna/

My receiver is a Pioneer sx-750 that is in my basement. My antenna set up WAS a cheap $3 clear plastic dipole mounted with thumb tacks in the attic of my 2 story home. I have rg59 (probably not the best but it was free and it is what I have) coax running from the dipole (used balun to connect) down to the basement receiver where another balun was connected to the 300 ohm leads on the receiver.

I would get decent reception, but I live in a smaller town that is smack dab in the middle of 4 larger cities (each city is about 30 miles away in every direction from my home-home being in the middle), I wanted to try and find something that was omni-directional to "improve my choices" on stations. The omni directional desire lead me to the J-pole. The ease in construction was another factor, and finally, the fact that I had all of the parts just laying around (plumbing stuff), it looked like an easy and fun project.

Well it took me about 2 hours to make and install (installed in the attic again as association rule prevent any outside antennas). I really did not expect anything big, but I was instantly impressed. Signal strength on a typical station 30 miles away went from "one" on my signal meter to 3 to 3.5. Signals at just above zero went to just above 1 to 1.5. Really impressed with the gain (if that is the proper term as this is all new to me). I even picked up a known station in a town about 80 miles away, but while I heard everything clearly, it was definetly not pleasing to listen to.

I also noticed (tell me if it is just my imagination) that the stereo separation seems "more", the sound seems "better" and I actually backed off on some of my bass and treble. Is this right? Did I just improve on how my stereo sounds while listening to fm by improving my antenna?

So far I am really happy. I have been playing with the adjustments of the antenna by moving the clamps (they are made to be adjusted up or down) that the coax connects to on the elements to see what it does to signal strength. Moving the connection/clamps down and my signal gets weaker, moving them up and it gets stronger. I am at about 8 to 10 inches above the bottom plate right now, and will play with it a little more in the morning. This time I will use a walkie talkie and have my wife at the receiver while I move the clamps. I am tired of climbing 2 flights of stairs, then a ladder, then walking across the attic from joist to joist to get to the antenna (near an outside wall), make an adjustment, then go back down and do it all over again.

So far, the only negative I have noticed is an increase in hiss. Even with stations that I had a descent signal with before and have a much greater signal now, have hiss. The closest station from my home (and the best signal) has no or next to no hiss. I assume the hiss is normal? Is there anything I can do to help eliminate it like using a choke near the feed point? I did leave some extra length in the coax just in case, but still need to bone up on what is the chokes actual purpose. Is it for RF?

Like I said, I am new at this, and am having fun, so if I am missing anything, let me know. Wanna do it right! Hopefully this post will help a few others out as well. This is a really easy and fun project. I used copper as I had it laying around. To buy it might be a little pricey right now (thanks China), so I was wondering if EMT conduit would work just as well? I used 3/4 inch for the long and 1/2 inch for the short length. The clamps are just some 3/8th soft wall tubing that was pounded flat, then a hole drilled per the instructions. I also used a piece of wood at the top of the short pipe connected to the longer pipe as a brace for the two elements (in other words I tied them together with a wood support) to help strengthen things up.

No fancy mounting, just zip tied to a couple of screws in the 2x4's in my rafters. I have the antenna mounted vertical.

OK, time to go look for some more "new" radio stations. Sorry for the long post, but I just had to share. YD

That's real cool. I'm going to make one for myself.

I have a motor operated antenna on the roof and I also experienced both the hiss (quiet periods between music), better stereo separation and better sound overall with a stronger signal (when I tune it to the strongest signal).

I guess if you get a stronger signal than you'd also get all the noise that comes with it. The hiss might also be the multipath effect (althiugh I don't know that for sure, just specuilating)

Actually forgot to add (I don't think it is mentioned in the instructions on that site) the shield of the coax goes to the short tube clamp, the center to the long. I used eyelet crimp connectors right on the bolts that tighten the clamp. Good luck, YD

I've hooked up several antennas in my attic and never was happy with the reception. Of course I was using 300 twin lead wire that I installed in the wall when I built my house, didn't know any better at the time.

Finally, I wised up, unhooked the shielded cable that went to the TV jack in my office (where my receiver is), pulled it up on the roof, and installed a Weinguard omni on an old satellite mast, then hooked this to my receiver...big difference. A lot more channels, way better reception, also got rid of the interference I was picking up. By all rights, your J-pole should get better reception than the cheap omni I'm using.

That is cool. Tomorrow I'm going to swing by the scrap-recycling place and see what diameter metal tubes and what plates they have lying around; probably won't take me more than a few days to get all the parts needed to try this, as scrap-metal prices. Should be fun. THANKS!

Rookie Disclaimer:

I need to say I am extremely novice so what I say may come out wrong in my attempt to pass on info. Please correct me if I use the wrong terminology or make an incorrect assumption.

With that being said, I did some fine tuning today and gained another "number" on my signal strength meter.

I'm not sure what it does (found reference to it on another j-pole site), but I made a 4 turn 6 inch loop in the coax near the antenna using electrical tape and zip ties. That seemed to cut down on the hiss I was hearing when compared to yesterday. It could be my imagination, it could be atmospheric influences, it could be time of day, I don't know, but, that is what I have found.

The next thing I did was play around with length as I made my j-pole slightly long. I read a few different website calculators and they all had different numbers for length at the same given frequency (I chose 98 mhz) so I purposely left things a little long.

Instead of cutting the pipes, I just used a length of copper wire at the bottom of antenna and some clamps. I now can slide the whole thing up and down to lengthen and shorten the whole "length" of the antenna. I went with the exact numbers that the website I posted in my original post listed (84" for long and 28 for short). That seemed to boost my signal strength a little.

Then I got my wife to sit in front of the tuner with a walkie talkie, and set the tuner at a radio station right at 98 mhz (a rap station-I turned the volume off). It gave me a signal of 2 on the meter with no real hiss. I went up into the attic with my walkie talkie and started to slide the cable connection points up and down until signal strength went up or down. I found the best spot for signal strength and tightened down the clamps. One thing to note, the signal strength went down as I approached the antenna, even worse when I touched it, so I would step about 10 feet away every time I made an adjustment and then ask my wife what the signal number was.

Finally I played with location of the antenna. This netted my biggest gains in signal strength and eliminating noise. Originally I had the antenna in the center of the attic (the peak) but up against an outside wall. I moved the antenna about 10 feet from the wall (still at the peak of the attic) and gained about half a number on the strength meter and I really have to try hard to hear any hiss. Most of the stations don't have any or just a small amount.

So at this point, I am done messing with it. I will listen to various stations at various times of the day and weather conditions to see what happens. My 80 mile away station I mentioned earlier now kicks in stereo. Not a particuliar favorite station, but, a good guide at how well things are working. YD

VERY GOOD report! Thank you!

Your observations about proximity of the antenna to you and other objects is interesting.

I usually bring a spare tuner to my attic when I'm tuning, just a tip. Great job so far. You have me very curious. I don't think I can get any better reception than what I am already getting with my setup of steel wire in a large coil but I'm leaning towards trying this for fun.

Thanks. Yes, it is a fun, simple, quick, cheap, and easy enough. I really enjoy the improved sound. :thmbsp: I just wish I built one sooner, but, when I stumbled upon this website while trying to solve a minor problem with my tuner, I discovered a whole new resource for information. Did not know what I was missing. Great site! Still have alot to learn.

dmagalhaes, you gotta do this. Hopefully others who build one will comment on their results. Turns out while searching last night, I found an older post on this site by some one else with the same link. He posted the info awhile ago, and seems to be pleased with the results. There is another site member who made one with similiar results.

Paul C., I just read your article "New filters for old tuners" . Nice read, thanks. Now I want to do that mod! That and a 75 ohm terminal on the back of my tuner. After that, I will have my tuner get the once over by Radio X. (He's just about 35 miles from me) Seems I'm going down a slippery slope and your not helping any

I was thinking about making a few variations. I am considering making one J-pole from copper wire. My thinking is this could be installed under vinyl siding if someone really had to keep an antenna hidden and had no attic. The other thought is to make one out of electrical conduit and steel (I weld as a hobby). Not sure how that would work, but I am willing to give it a try. I would of course paint that one up.

I am still tring to figure a way to "sneak" this antenna on the roof. Let's see, I could put a wind sock on it, a flag, a small wind mill, a weather vane, anything to try and "conceal" it :nono: Thanks, YD

If you are going to get your tuner aligned by Radio X, they also can do the filter mods, and align. While he is doing the filter mods, he can also match the filters, going several steps further than what I did. So, if you are having it aligned anyway, just let them do it all.

I am still tring to figure a way to "sneak" this antenna on the roof. Let's see, I could put a wind sock on it, a flag, a small wind mill, a weather vane, anything to try and "conceal" it

Why not just spray paint it sky blue?

*chuckle*

*pictures a bird sitting on invisible antenna*

Next project to tackle. All out stations have moved the HD signals to the best antennas I guess. Now you have to have a vertically aligned antenna to get a decent signal in my area (polarization for the drive by crowd - car antennas).

This one looks like it will work very well with vertical polarization. We'll see when I get it built sometime this summer.

Here's my J-pole installation.

Works great! All it needs is a blinking red light on the tippy-top.

FauxHall said:

Here's my J-pole installation.

Click to expand...

Did you make that to facilitate adjustment? Do the screws pierce the uprights or just snug things up to keep them from moving? I ask because it looks as if we had similar things in mind while building a j-pole...







And Yankee Dog, :worthless


J.R.

Hehe build a 160m j-pole.

J-poles work great. Fun to construct.

How do you ground these antennae against lightning strikes? I don't want to do it wrong orfor sloppy and jeopardize my Homeowner's coverage

Andyman said:

How do you ground these antennae against lightning strikes? I don't want to do it wrong orfor sloppy and jeopardize my Homeowner's coverage

Click to expand...

I built a threaded stem into the base if mine for a ground lug...



...big fat wire from there to the tower, ground stake, water pipe etc.


J.R.

I was reading up on it and it said something like not to use a water pipe but to use a dedicated stake like half your yard away from the antenna. I'll have to dig into it a bit more...

On mine, the white block is a hard plastic. The connections are made with pointed sheet metal screws from either side. That ensures good metal to metal contact. To adjust, just back off on the screws and reposition, then re-tighten.

Here in the part of California where I live, we almost never have lightning or thunder so I took my chances. If I were in Florida, I would take appropriate precautions. I did ground the outer conductor on the coax with a gizmo (grounding block) from RadioShack and a three foot copper rod. It seems to reduce the background noise.

Here's a previous thread: http://www.audiokarma.org/forums/showthread.php?t=53582