Can I get a better aerial than this ?

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fmuser877
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Can I get a better aerial than this ?

Post by fmuser877 » Sun Feb 27, 2022 10:03 am

It's OK but wonder if can get a better one?
https://www.superyagi.com/88108mhz_jpol ... 84551.aspx
I am willing to spend around £150 to 200 but do any come from the UK?
this defo much better than the dipole before.
But only getting about 4 miles. :(
I cannot go higher due to how windy it gets to. :(

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teckniqs
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Re: Can I get a better aerial than this ?

Post by teckniqs » Sun Feb 27, 2022 11:00 am

Dominator

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Re: Can I get a better aerial than this ?

Post by fmuser877 » Sun Feb 27, 2022 11:07 am

will see if can see any that are in stock. :tup

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Re: Can I get a better aerial than this ?

Post by fmuser877 » Sun Feb 27, 2022 11:09 am

https://www.lpfmantenna.com/product/250-watt-free-tune/
Like that however, can only see US ones right now.
for extra they can ship so will look into one.

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Re: Can I get a better aerial than this ?

Post by teckniqs » Sun Feb 27, 2022 12:10 pm

fmuser877 wrote: Sun Feb 27, 2022 11:09 am https://www.lpfmantenna.com/product/250-watt-free-tune/
Like that however, can only see US ones right now.
for extra they can ship so will look into one.
It'll be worth it. :tup

...How much power are you runnin? It might just be easier to up your power in the long-run.

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Re: Can I get a better aerial than this ?

Post by fmuser877 » Sun Feb 27, 2022 12:44 pm

15 to 50 watts

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Re: Can I get a better aerial than this ?

Post by teckniqs » Sun Feb 27, 2022 12:59 pm

Have you checked the SWR on that J-pole?

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Re: Can I get a better aerial than this ?

Post by fmuser877 » Sun Feb 27, 2022 1:06 pm

the TX shows 0 refected feedback for me
on the indoor aerial, it has 1 to 2 bars.

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Re: Can I get a better aerial than this ?

Post by Albert H » Sun Feb 27, 2022 1:15 pm

The best amplifier (and usually the cheapest option) is a good antenna. The "Dominator" is just a somewhat strange way to make a J-pole - it works just the same....

A J-pole is a ½-wave end-fed vertical, with a ¼-wave matching section. It efficiently takes your unbalanced coaxial feed and does a huge impedance transformation to feed the end of the ½-wave. It has a very slightly rising radiation characteristic, and is truly omni-directional (as long as it's in free space). It's a good idea to wind 5 or 6 turns of your coax into a coil of about 6" diameter, about a meter below the feedpoint to prevent RF coming back down the skin of the coax. This is an RF choke (NOT a balun as it is often described by people who don't understand aerials). I usually just wind some of the feeder up and either tape it into a coil (or use cable ties). I usually strap the choke to the mounting pole.

The J-Pole presents a DC-short to the transmitter - this allows a quick continuity check to see that the coax is unbroken, and provides a useful degree of lightning protection.

You'll find that the field strength from a "Dominator" will be exactly the same as a J-Pole, and the "Dominator" is really expensive.

I used to make J-poles out of almost any pieces of metal I could find. I've even used the top of scaffolding with a ¼-wave stub strapped to it as an "improvised" J-pole! You can build them out of any old junk, and there are calculators on line to give you the dimensions for your frequency of choice. https://m0ukd.com/calculators/slim-jim ... alculator/ works fine. With very little work, you can get a really low SWR!
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Re: Can I get a better aerial than this ?

Post by Albert H » Sun Feb 27, 2022 1:25 pm

There is a further version of the J-Pole, called the "Super-J". This provides several dB of gain, but is more than twice the vertical size of an ordinary J-pole.

Other effective aerials include the single-slot colinear: http://sm0vpo.altervista.org/antennas/6dbvhf0.htm - Harry's a bit over-enthusiastic about the gain from this design, but you can easily achieve 4 dB over a dipole! I've built versions of this design, and had great results with them.

There is also the 0.66-wave end-fed vertical..... This shows a rising radiation characteristic, and serious gain, but is a nightmare to match accurately. I've used them on lower sites with success, but wouldn't recommend them for a beginner.

I've also built lots of aerials with groundplanes - ¼-wave, ⅜-wave, ⅝-wave and ⅞-wave versions. Each has their benefits, each has different matching requirements, and each shows a different radiation characteristic, but all of them are more difficult to build than a basic J-Pole. I'd probably stick with the J-Pole at first. You're certain to get good results if you bother to do some basic calibration.
"Why is my rig humming?"
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Re: Can I get a better aerial than this ?

Post by teckniqs » Sun Feb 27, 2022 2:33 pm

A station which used to run from a large tower block in Bracknell changed their usual J-pole to a dominator and was reaching the edge of Southampton with it, made a massive difference. 👌

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Re: Can I get a better aerial than this ?

Post by fmuser877 » Sun Feb 27, 2022 4:28 pm

that's some miles

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