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Author Topic: whip antenna and icom AT130  (Read 1351 times)
XE3LW
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Posts: 5




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« on: June 29, 2008, 09:00:37 PM »

Hi
This my first time I install a HF mobile station, my plan is to connect an Icom AT130 antenna tuner to a 8´ whip antenna similar to the AH-2B mobile antenna from Icom.
Does anybody had experienced this setup before? What performance can I expect from this setup?
73´s
Oscar-xe3lw
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K8KAS
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Posts: 578




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« Reply #1 on: June 30, 2008, 07:08:22 AM »

Very poor mobile antenna on 75/40/20 and 17 meters. Good on 12 and 10 meters. If thats OK your all set.
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K0BG
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Posts: 10248


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« Reply #2 on: June 30, 2008, 07:59:32 AM »

Yes. Go to my web site, and look under Antenna Couplers.

The biggest problem is the antenna is essentially a based loaded one, and the efficiency will be 1/2 a center loaded one, all else being equal.

Also, length matters, and increasing the length by 50% will double the efficiency. But that's not all. You need a very good ground connection on the coupler, and the output side must be kept short; inches not feet. And, it cannot be coax!

Alan, KØBG
www.k0bg.com
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W5DXP
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« Reply #3 on: July 02, 2008, 05:27:55 AM »

The following web page summarizes a number of CA 75m mobile shootouts. On 75m, an 8 foot whip plus autotuner is about 14 dB down from a good 75m bugcatcher or screwdriver, i.e. it radiates 1/25 of the power radiated by a 75m bugcatcher (which is not very efficient to start with). 100 watts in results in about 1/2 watt out. Enjoy your 75m QRP. :-)

http://www.w5dxp.com/shootout.htm
--
73, Cecil, w5dxp.com
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AA4PB
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Posts: 14354




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« Reply #4 on: July 02, 2008, 12:25:37 PM »

Yes, the 102-inch whip will be many dB down from a large screwdriver with a big top hat (take a look at the monster reference antenna). If you don't mind driving around with something like that on your vehicle and 75M is your thing then great. The shootouts always take the worst case condition (75M). You'll find that the 102-inch whip is not nearly so many dB down on 20M or 15M. Even on 75M it will make contacts around the state, just don't get into a competition with one of the monster antennas :-)
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Bob  AA4PB
Garrisonville, VA
W5DXP
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« Reply #5 on: July 02, 2008, 06:22:40 PM »

Please don't shoot the messenger. 75m is the only band for which I have actual shootout measurements.

I actually ran a 11.5 ft (138 inch) whip with an SG-230 autotuner on 20m-10m and it worked very well. If someone wants to use that configuration, I would suggest going with a whip longer than 102 inches - up to the legal limit. Simply add a base section to a CB whip.
--
73, Cecil, w5dxp.com
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