J-pole antenna advice

[thewisepranker]

It's not ideal, but it'll probably work. The right-angled SO-239 will eat up a considerable amount of power and make decent tuning more difficult than it needs to be, as it is pretty much impossible to make a practical right-angled connector with decent performance.

Unless you can seal the box around the two poles on the top face (when the aerial is mounted in its correct orientation) and the lid, it will only collect water and put it down your coax. I think you'd be better off having the connector coming out of the top, but then it's pointing away from your transmitter, which is a bit of a nightmare.

[Sietedj]

It's not ideal, but it'll probably work. The right-angled SO-239 will eat up a considerable amount of power and make decent tuning more difficult than it needs to be, as it is pretty much impossible to make a practical right-angled connector with decent performance.

Unless you can seal the box around the two poles on the top face (when the aerial is mounted in its correct orientation) and the lid, it will only collect water and put it down your coax. I think you'd be better off having the connector coming out of the top, but then it's pointing away from your transmitter, which is a bit of a nightmare.

The box I intend to isolate with silicone to prevent the water from entering.
I will test to see if water does not enter, but I will do it another way.
Thank you!!

[Albert H]

Do you recall what format the music was?

The pop of the day and some oldies.

[Albert H]

I've been thinking about doing something similar with a solar panel and some leisure batteries. But I'm unsure how to link from 15 miles away,

You'll be lucky to recharge "leisure batteries" from solar cells - it can be done, but you need a lot of cells. Luckily, I was given lots of solar cells in the USA, and we supplemented these with a little wind turbine. The most complicated part of the whole deal was controlling the charging of the batteries. There are "alternative power battery controllers" built for yachts and other off-grid uses - you'll find them on eBay for a few quid - and these can be ideal.

Linking 15 miles isn't too difficult if it's line-of-sight. I used to go quite a lot further in London, from a studio in Kent to Crystal Palace. There are several viable approaches, but if you've got line-of-sight, you might get a microwave link to work over that range. 15 miles is about the most I ever achieved, and lining it up was very difficult!

Next option - and the one I favour - is UHF. TV aerials don't look out of place almost anywhere, so you can hide your link aerials in plain sight. You can also buy incredibly high gain aerials for £10 - 15, complete with mounting kit! I did a tricky 20-mile, electrically noisy path with just ½ Watt going into the aerial and got full noise-quietening. The stereo link was around 600MHz. The receiver was based around a TV tuner-head (TSA5511 synthesiser) tuned by a PIC, then the 35MHz IF from that was filtered then simply down-converted to 10.7MHz (by mixing with a crystal in an NE512) and then into a conventional IF strip. The problem you're going to have is finding an engineer with the technical chops to be able to build Band IV and V gear.

The last option is Band I. Everyone and his Auntie uses Band I - and over 15 miles, you'd probably need some serious link power, which will make your source end easier to find. Not a good plan unless you do it in several "hops", but that's a hell of a lot of hassle and difficult to make to work reliably.

Why don't you pre-record your programmes to a cheap MP3 player and use that at the transmitter site? A simple time-switch (or "Vox" - sound-operated switch) could make sure that the gear is off when you go back to collect it.

[Maximus]

It's probably not ideal, but I've seen engineers using Jubilee clips to temporarily clamp the coax to the pipes. It surprisingly works well.


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[Sietedj]

It's probably not ideal, but I've seen engineers using Jubilee clips to temporarily clamp the coax to the pipes. It surprisingly works well.


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For now I will try to see how it works.

I wanted to ask: should the antenna of the mast be isolated? Or is it indifferent?
Thank you!!

[thewisepranker]

Don't isolate it from the mast.

[Sietedj]

Don't isolate it from the mast.

OK, I had seen some who put a PVC pipe to isolate the mast and did not know if it should do so or not.
Thank you, see if I can try it this Sunday.

[Sietedj]

I have been testing the antenna and surprisingly works well !!!! I tested it with a small transmitter that has 3W with the dipole I currently have, and with the J Pole it has 2.5W and 0 SWR. I'm going to remove the SO-239 and put the RG-58 directly, since after that I have to connect the drop cable to the transmitter which is RG-213 and there would already be many connectors.
Thanks to all for the help!!!

[Maximus]

I like the encloses that you've fitted. Good job


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[Albert H]

The plastic box is a great idea! You can easily seal it against water, and it'll keep your connectors clean.

[radio-berlin]

How did u get on with this j-pole? I was talking to a couple of board members who swear by this antenna. Im curious if you noticed much difference

[Sietedj]

How did u get on with this j-pole? I was talking to a couple of board members who swear by this antenna. Im curious if you noticed much difference

Hi, I have not been able to test well yet. I did a test with the J-Pole a few meters lower than the dipole I have and more or less was the same, I guess when I install it on top of the mast will go better. I'll tell ya how it works when I install it.
Regards!!!

[Sietedj]

Hello, after a long time I finally installed the antenna. It had a dipole (DP100) and the problem that when there was thunderstorm the transistor burned.
With this antenna it seems that I have a smaller range, not much but it shows something. I have to say that it is set for 104.2 and I have had to change to 103.4. It has 1.4 SWR, so it works a little worse. Now I have to wait until there is a storm and see if everything is going well. I leave you some photos of how it has been and thank you for the advices !!!

[Electronically]

j pole looks good. but when jpole is outside would it not turn green because it's made of copper ? I was going to make it 22mm diameter then thought wait a minute they'll turn green .

[MC Spanner]

That takes years, and anyway it will go dark brown first. And why are you bothered?

[Electronically]

That takes years, and anyway it will go dark brown first. And why are you bothered?

bothered to the fact it should last not to turn green .Few folk have said it turns green I never asked how long the green takes to appear .so I'm no using copper ill use aluminium instead .

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[yellowbeard]

Only the surface of the copper is affected, it won't rot thru and it takes decades to go from dark brown to green. I have a gas line running around the outside of the house for 40 years, it's perfect and no green. If you are taking that antenna down again it'd be more important to switch the steel jubilee clips for some copper pipe clamps and solder them, the steel will cause a problem sooner than the copper.

[Electronically]

I totally agree with you yellow beard .so 40 years seems a life time not bad .I agree on steel clamps they rust easily

Only the surface of the copper is affected, it won't rot thru and it takes decades to go from dark brown to green. I have a gas line running around the outside of the house for 40 years, it's perfect and no green. If you are taking that antenna down again it'd be more important to switch the steel jubilee clips for some copper pipe clamps and solder them, the steel will cause a problem sooner than the copper.

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