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Old 05-13-2011, 11:00 PM
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Default Isotron Antenna

I'm trying to get on HF, like 80m. Don't have enough room at my location for a dipole or some such. ~90' is the most length I have.

Has anyone used the Isotron antenna and is it any good? This would be slick at the right price, but I'm somewhat skeptical as it can't be as good as a longer wire type. Also thinking of using a loaded mobile type antenna and using some ground radials ( which isn't he best solution ). One of these nice verticals would be nice, but cannot afford $450+ for one.

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Andy
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Old 05-13-2011, 11:38 PM
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I don't have one myself, but I use eham as my reference for ham gear reviews.

Isotron Review Bilal Isotron Product Reviews
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Old 05-14-2011, 1:28 AM
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If your choices are between using an 'Isotron' and no antenna at all, then go ahead and use one if you want. My suggestion would be that mobile antenna and some radials. Or some other type of loaded antenna. It wasn't an 80 meter 'Isotron', but I have owned a 10 meter one. Can't say I've "used" it, only that I've owned it, and it wasn't for the lack of trying! I wouldn't have another 'Isotron' if 'they' paid me to take it.
- 'Doc
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Old 05-14-2011, 8:07 AM
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Build a "doublet" antenna same as a resonant dipole cut it to the maximum lengle you can install, use 450 ohm ladder line instead of coax, get a tuner with balanced output. Install the antenna as high as you can go run the ladder line to tuner, enjoy. This setup will allow decent HF operation on all HF bands and will out perform the other suggestions you offered.
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Old 05-14-2011, 9:53 AM
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I've had one and it works in the sense that some RF does radiate - mostly from the coax feedline!

I would suggest if space is tight, consider a Hamstick dipole. I used one on 80M for a while and it was much better than the Isotron, though it's still a compromise.
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Old 05-14-2011, 11:39 AM
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I agree here and you can put out a very respectable signal with a 90ft doublet on 80m. Check out an antenna called the ZS6BKW, its a modern variant of the G5RV but unlike the G5RV which was designed as a 20m gain antenna and random dipole on other bands the ZS6BKW is computer designed to match on 40, 20, 17, 12, 10 and 6m with no tuner.

It works about the same as a G5RV on 80m using a tuner and its 94ft long which can be bent to fit your 90ft space.

I used to be a big user of G5RVs but have now switched to the ZS6BKW for most applications. You can make one for a few $$ in wire and 450 ohm ladder line or 300 ohm TV twilnead. I would recommend starting with the 94ft length and trimming the 40ish ft feedline until 40m matches and the remaining bands will fall into place.

Otherwise I have not used an Isotron but have read some disappointing reports on them.
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Originally Posted by rfradioconsult View Post
Build a "doublet" antenna same as a resonant dipole cut it to the maximum lengle you can install, use 450 ohm ladder line instead of coax, get a tuner with balanced output. Install the antenna as high as you can go run the ladder line to tuner, enjoy. This setup will allow decent HF operation on all HF bands and will out perform the other suggestions you offered.
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Old 05-14-2011, 5:52 PM
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Quote:
Originally Posted by rfradioconsult View Post
Build a "doublet" antenna same as a resonant dipole cut it to the maximum lengle you can install, use 450 ohm ladder line instead of coax, get a tuner with balanced output...
That's exactly what I use, and it works extremely well on all bands.
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Old 05-14-2011, 7:17 PM
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In the late 1990's I used the 80 and 40 meter Isotron while I was doing temporary, but long-term consulting work in the Rochester, NY area. My living quarters was a bedroom with a small second floor outside balcony. I mounted the Isotrons to a 10 ft mast, which was grounded to the outside water faucet directly under the balcony. My rig was an IC-706, with 100 watts. I put this antenna up to try to maintain skeds with friends in Ohio, Indiana and Kentucky. Bottom line: It did work. I was able to hear and be heard in these places. I even tried a little DX on 3795 one night when I heard a German SSB station and was able to work him, too. I have the QSL card to prove it. On 40 meters, I was also able to work a buddy in Central Florida most of the time.

At my permanent QTH, where I have some room for "real" antennas, I would not consider using the Isotrons, but when you have no room for anything else, they will work. You will have to follow the assembly instructions carefully and become very aware that this antenna must be on a good grounded mast. They are very narrow banded, but with patience, can be adjusted for the parts of the bands you want. I had an auto-turner for my IC-706 and that helped with the matching, giving me a wider range of operating frequencies without adjusting the antenna itself. But you can operate without a tuner so long as you make the right adjustments on the tuning stubs of the antenna.

I know many operators have trashed this antenna, but I can tell you I was happy with the performance for what it was.
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Old 05-14-2011, 8:18 PM
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I would use the hamstick on 80 meters as a dipole I have wrkd a few guys with them and they had no complaints..

DOCTOR
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Old 05-15-2011, 10:06 AM
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Using very physically short radiators such as Hamsticks probamatic, yes you can get an acceptable VSWR but your radiation effecency really suffers, in the order of 1-3 % for a hamstick (7 ft.) style antenna at 80 Meters.; so your 100 Watt ring has an ERP of 1-3 Watts. Also if you use a vertical HF antenna your grounding network becomes very important, again don't equate low VSWR with antenna effecency. A general rule-of-thumb is get as much balanced wire as high up in the air as possible.
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Old 05-16-2011, 12:12 AM
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Thanks for all the replies. What does anyone think of this end fed unit from Radio Wavz? This could work, but would only have room for a 40m one. I like the idea of being able to use coax so I can route it thru my house and down a metal clothes chute to basement. Having high end currents have been mentioned. Is this a problem with this one? I can run it from the tripod on the roof of the house to the garage.

A
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Old 05-16-2011, 9:06 AM
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Try this one..I have one no complaints on it, and check eham for reviews..

ULTIMAX HF ANTENNAS items - Get great deals on items on eBay Stores!

73
DOCTOR
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Old 05-21-2011, 7:04 PM
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Where I live at - most people puts up a tower.
On that tower they put a 20 meter beam
On top of the 20 meter beam - they usually put a 2 meters antenna or a 6 meters antenna.

Ringo Ranger or a Diamond or a Astron.

Then off to the side they put up another 2 meter beam or a 440 beam and a 10 meter antenna of some sort.

For their HF they put up a NVIS - antenna and use a MFJ antenna tuner and some ladder line.

The G5RV is designed for 40 meters and does a little on 30 and 20 as long as you have a good antenna tuner.

That does not mean that if you put 100 watts into it that you get 100 watts out of it at 20 meters.
It just means that it will work to a degree on those frequencies.

The downfall is - that it does not perform if you get it near any type of metallic object such as gutters, soffit and fascia, antenna towers, flashing on the roof etc...

Build an antenna for the frequency you desire to transmit on.

Build several antenna's and install them until you find the one that works the best for you.

The bottom line is that the G5RV antenna is no good for close up work.
You probably won't be able to even talk to your friends 10 miles away - but could talk to someone 3000 miles away.

A NVIS antenna is good for about 5 miles to 1500 miles and that is it!

So there is no real right answer and there isn't anyone that can give you advice with a 100% guarentee - especially when you are there and we are here and we can't see your situation.
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Old 05-21-2011, 7:12 PM
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Quote:
Originally Posted by rfradioconsult View Post
Using very physically short radiators such as Hamsticks probamatic, yes you can get an acceptable VSWR but your radiation effecency really suffers, in the order of 1-3 % for a hamstick (7 ft.) style antenna at 80 Meters.; so your 100 Watt ring has an ERP of 1-3 Watts. Also if you use a vertical HF antenna your grounding network becomes very important, again don't equate low VSWR with antenna effecency. A general rule-of-thumb is get as much balanced wire as high up in the air as possible.
I couldn't stress enough how wise the above advice is.

Using a shortened mobile antenna in a fixed antenna is ludicrous, unless restrictions absolutely dictate it. then, it becomes a matter of anything being better than nothing.

As to the balanced antenna, this is EXCELLENT advice. The requirements for a superior RF ground are virtually eliminated, and using balanced line and a tuner insures that it will work well on multiple bands. It's super easy to build, and once you get used to it, super easy to tune and change bands.
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