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Author Topic: 706 mkII AH4 part tune on 6mt  (Read 386 times)
KB0WOY
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Posts: 3




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« on: February 05, 2004, 07:24:08 AM »

Hi all I have a AH4 102 whip it tunes all bands but
50.000 to 52.800 it will tune 52.800 to 54.000
What to do?I have the tuner on a 4ft mast 3 inch
12ga wire from tuner to ant.
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N8EMR
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Posts: 235




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« Reply #1 on: February 05, 2004, 09:31:58 AM »

The Ah4 will tune most whips, however it will not tune an antenna on the frequency it is resonant. Best bet is to hang a small wire off the top of your antenna and ship the resoant freq away from where you want to operate. The 102 while capable on tuning 80-6m, will not effective radaiate a signal on 80m.
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K0BG
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« Reply #2 on: February 05, 2004, 10:47:46 AM »

You've been given some false information.

First, the AH-4 will easily tune all of 6 meters whether or not the antenna in question is resonant or not. I suspect the problem is the fact you have it mounted on a 4 foot mast. You didn't state how the AH-4 was RF and DC grounded, and it must be.

A 102" whip can not be matched by the AH-4 on 75 meters (or 80 meters). The minimum length for this band is about 35 feet (more is better obviously). Although not advertized to do so, with a wire about 80 feet long, it'll tune 160 as well.

The fix? Mount the AH-4 very close to the ground, and use at least an 8 foot ground rod making sure to keep the lead to the ground port short. Use some sort of extension on the whip to increase its length to about 12 feet and you'll be surprised how well it works. For best performance, use a long wire being careful not to have it near a half wave on any band.

Alan, KØBG
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KB0WOY
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« Reply #3 on: February 05, 2004, 02:42:55 PM »

Hi!it is on a Chev Tahoe 4ft mast welded to the trailer mount 3inch ground strap to mast from tuner on the out side of truck mast ground to frame tried 6m ham stick. I added more wire no good.
still does not tune on 6m 50.000 to 52.800
it does tune 160 to 10m (SWR 1.1 pow full scale)
sig noise rise on all bands.from ant out? who knows
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K0BG
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« Reply #4 on: February 05, 2004, 03:09:43 PM »

Robin, instead of carring this on forever over eham.net, send me an e-mail at k0bg@aol.com and we'll get you up and running.

I used an AH-4 mobile for several years before upgrading to an SG235 and SG500. I wrote several articles about this set up and if you'd like to read them, the article URLs are:

http://www.eham.net/articles/4407, and 4424, 4425, and 4623.

Alan Applegate, KØBG
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K3WVU
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Posts: 491




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« Reply #5 on: February 14, 2004, 09:34:53 PM »

I agree with N8EMR and I have the same problem with the AH-4, except I'm using it with a long piece of wire as a base.  The instructions say to avoid wire lengths the are 1/2 wavelenght or multiples of 1/2 wavelength at the frequency on which you want to operate.  This generally doesn't become too much of a problem until you get up to 10M or 6M.  Mine will not tune part of 6M either.  If possible, change the length of the antenna.  To find antenna lengths that may give you a problem, use the following formula:

Multiple of 1/2 WL = 300/f*1/2*(1,2,3,etc)

Good luck,

Dwight K3WVU
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