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Author Topic: HF auto tuner vs. screwdriver antenna?  (Read 2993 times)
WS9K
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Posts: 13




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« on: July 27, 2002, 08:03:53 AM »

I Love my IC-706MKIIG, but I'm tired of swapping hamsticks.
I'm trying to decide what's better, an AH-4 or RT-11 auto tuner or a screw-driver type antenna.
I'll be using My Ford Ranger 4X4.

The screwdrivers look goofy to me and seem like they would not hold up to years of hard use.

On the other hand, the how effective is an auto-tuner and whip?
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K0BG
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Posts: 10248


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« Reply #1 on: July 27, 2002, 01:19:33 PM »

There are a lot of good screwdriver antennas and the review section of this site has a lot of information on all of them. Be careful selecting one, as some exhibit a large amount of electrical noise adding difficulty to tuning.

I personally don't like ham sticks. They are little more than dummy loads on a stick. The fact that a lot of people use them with success just goes to so you how little radiated power it really takes to make contacts.

If you look up my call on this web site, you'll see a picture of my mobile antenna. It is 13.5 feet long and resonant on 20 meters. The input impedance is just under 24 ohms, so it can be use without the tuner if I need to. Behind the antenna in the left fender well is the AH-4. It easily tunes the antenna from 40 thru 6 meters. Admittedly, the optimin radiation resistance is not achieved on fourty, but the losses thru the tuner (<2 db) are actually less than a true 40 meter coil would add. After nearly 2 years, I have had no problems of any kind, on any band (40 - 6). One advantage for sure, QSY is nearly instantaneous. If you want more information on the tuner, let me know. I have pictorials and schematics of the AH-4, and I'll be happy to explain to you how it works.

What ever you end up using, make sure you take time to properly ground everything in the vehicle, properly wire and fuse the power leads (don't use the weed lighter socket), and properly mount the rig so it won't move even in a head-on crash. Safety First! is always best.

I also use a Heil headset with mine, but check your local laws before you try it.

Alan, KØBG
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N7PTM
Member

Posts: 21




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« Reply #2 on: August 04, 2002, 02:51:32 PM »

I feel the same way!

I found the answer in the Am-Com "ASAC" (automatic screwdriver antenna controller) which, with a push of the 706's "tune" button, takes over the function of driving a screwdriver antenna's motor. It raises or lowers the whip until the right SWR is attained. Meanwhile, you're looking at the road ahead, still moving.

http://www.amcominc.com

or see my 706 page: www.tibpriors.org/ham/icom706.htm
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KG4OXP
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Posts: 89


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« Reply #3 on: August 11, 2002, 01:25:24 PM »

I use an ah-4 with a whip (actually an 8 foot LORAN-C shakespeare marine whip, that breaks into 2, 4 foot sections)..I've also used the ah-2b and cb whip with no discernable difference)

I'm not an expert in the field, but I always have rec'd excellent reports - most stations can't believe I am mobile...

I'm using a 706MKIIG as well.

By the way, I do have an RT-11 I use for portable use, which works well too.

e-mail me if you want more detail regarding my installation...
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