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Author Topic: ISOTRON ANTENNA  (Read 661 times)
WV2C
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« on: November 29, 2004, 06:41:25 PM »

ANY COMMENTS ON THE ISOTRON 40/80 METER ANTENNA? any body used it? Does it work?
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K5LXP
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« Reply #1 on: November 29, 2004, 07:57:56 PM »

With antennas, everything works.

My 40M isotron is usually 20dB down from a dipole. The feedline does a lot of the radiating. It's got a very narrow bandwidth. Signals easily heard on the dipole often disappear completely after switching to the isotron. I put it up just to see what it would do. It's closest competitor is a hamstick dipole and lots more expensive than one.  If you've got the facilities to mount one of these high enough to do any good, there are dozens of other antennas you could buy or build that would work better than an isotron, and for way less money.  They look cool though...

Mark K5LXP
Albuquerque, NM
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KR4BD
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Posts: 226




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« Reply #2 on: November 29, 2004, 08:17:51 PM »

For 3 years (1996-99), while doing a temporary job, I operated "portable" in Rochester, NY using the 40/80 Isotron combo.  I mounted it on a 10-ft mast which was strapped to a second floor balcony outside my bedroom.  I fed it with RG-58 (about 20').  From the mast, I ran a grounding wire to an outdoor water faucet directly below the balcony, near ground level.  This antenna WILL WORK if you install it properly, but I will admit, a dipole would be better if you have room.  I had no other antenna options at that QTH. I was able to maintain skeds with friends in FL, OH, IN and PA on both 80 and 40.  As for DX, I did work (and confirm) Germany on 3795 SSB while using this set-up.  My rig at the time was an "original" IC-706, running 100 watts.  I will admit, RF got into everything while I operated, but it did work!

Tom, KR4BD
Lexington, KY
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N6AJR
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« Reply #3 on: November 29, 2004, 09:30:28 PM »

it is better than no antenna at all but JUST barely  

http://www.hamuniverse.com/multidipole.html
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KT8K
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Posts: 1490




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« Reply #4 on: November 30, 2004, 07:04:54 AM »

There are tons of stealthy alternatives to the Isotron, that cost a LOT less and work a LOT better.  A dipole or vertical made from almost-invisible 20 gauge magnet wire will beat it by at least a couple of s-units, which is a HUGE difference.  Check out stealthy alternatives.  Give us more details on your situation and we'll make more concrete suggestions.
Good luck & 73 de kt8k - Tim
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W0FM
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« Reply #5 on: November 30, 2004, 07:22:06 AM »

The MFJ or AEA Iso-Loop 10-30 loop antennas will probably give you better results for the same small space.  They are High Q antennas and need to be tweaked (via remote box in the shack) frequently as the bandwidth is quite narrow.  But, unlike the Isotron, you will have multiple bands and better performance.  I worked a lot of DX with the AEA loop both on a short pole strapped to the deck rail and in the attic of my condo.  (These antennas are not for 40 or 80M if those are your top choices)

Good luck.

73 de Terry, WØFM
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KG8JF
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« Reply #6 on: November 30, 2004, 12:48:52 PM »

I have a 40M Isotron in my attic right now and I would not hit a sick dog in the kiester with it.  Sorry Mr Bilal.  Due to it's proximity to some attic mounted wiring I am going to have to trim some wire off the coil if I want resonance in the phone band.  It was just too much hassel.  I finally hung up a dipole and have lived happily ever since
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LU1HQV
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« Reply #7 on: November 30, 2004, 01:06:34 PM »

I have a 20 mts and 15 mts isotron... Works fair... I did some goods DX (Italy, germany..) but, I change for vertical rigth now..
I think this antenna works fair.. that's it...
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K1CJS
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Posts: 6046




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« Reply #8 on: November 30, 2004, 01:34:57 PM »

I have the 40/80 setup on my Yaesu FT-840, and I can usually get stations from all over the U. S. and Canada with them.  When I have another operator at my house who can transmit on the set-up, he seems to have good luck with them, too.

I'm not saying these antennas are the best, on the contrary, they are compromise antennas for use where you cannot use other, larger antennas, or for short term setups.  They get the job done.  I have no doubt that other antenna types can be better.

To you who say they are just barely better than a dummy load, I have to disagree.  Isotron antennas DO work.
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WB6BYU
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« Reply #9 on: November 30, 2004, 01:43:54 PM »

I had a 40m Isotron.  I gave it away after spending a
lot of time trying to tune it, and realizing that the
predominate radiation was from the outside of the coax
and/or the mounting mast.

In my experience, it worked just as well if you ran the
coax to the mounting location and connected the braid to
the mast, then loaded it as a long wire from the shack...
without the Isotron.  And a tuner is cheaper.
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K1CJS
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« Reply #10 on: November 30, 2004, 01:52:33 PM »

I should have added this to my original post:

The key to making the Isotron antennas work is to read and follow the assembly/installation instructions to the letter.

The person I got mine from told me he could only get limited good results with them.  I saw the way he had them set up when I went to pick them up, he was unable to ground them due to his landlords restrictions.  

When I set them up at my shack, I went the route spelled out in the instruction manuals, and to the letter.  I got better results than he did--as a matter of fact, he sometimes comes down to my shack, and is surprized when I show him the results I can get.

If you don't follow the instructions, you won't be able to get them to work too well, if you do follow the instructions, they'll work much better.
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K5LXP
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« Reply #11 on: November 30, 2004, 06:19:53 PM »

K1CJS- Yes, they do work.  And, they work better when the installation instructions are followed to the letter than if you don't.  Here's some other things that work too:  light bulbs, window frames, lawn chairs, bedsprings and probably the neighbor's cat if you could find a place to hook the coax to.  The truth of it is even when installed in the most optimum way as I did, it still sucked compared to anything else I had to compare it with.  My mobile screwdriver antenna on the bumper of the car in the driveway was just as strong or stronger than the isotron, and a dipole blows it away.  If you can put an isotron up 40+ feet where the ground losses won't eat it alive, then you could hang a random or other wire antenna up just as high, feed it with a tuner and get *much* better performance.  Yeah, isotrons "work" but so do the other aforementioned items. How well it works is subjective.  If it's the only antenna you have, it works great.  You will never miss the signals you can't hear.  If you have just about any other antenna, it will be the worst one you have. It's a solution waiting for a problem.

Mark K5LXP
Albuquerque, NM
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K1CJS
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Posts: 6046




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« Reply #12 on: November 30, 2004, 07:13:50 PM »

Yes Mark, I said they worked, and they do.  Yes, you never miss the signals that you can't hear--thats why I said they were a 'compromise' antenna in my first post.  Compromise, in this instance, because you lose something to gain something.  You lose the weak signals in order to be able to use the bands at all.

You get no argument from me that a dipole or a long wire work better--as I said in my original post.  The fact that you are able to receive some signals and also transmit mean they work.  As far as the other things you mentioned, yes they may work also, but the Isotrons work better than those.  Just because you couldn't get them to work doesn't mean they are no good--it just means you couldn't get them to work.

Chris, K1CJS
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