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eHam Forums => Mobile Ham => Topic started by: N4NOO on March 03, 2003, 10:54:36 PM



Title: AH4 & 102" Whip - Roof mount
Post by: N4NOO on March 03, 2003, 10:54:36 PM
Does anyone have any experience with the idea of monuting an AH4 and a 102" SS whip directly on the roof of a car.  I saw a picture somewhere on the web where someone had done this very thing.  He had either an aluminum or steel square over the AH4 and the whip directly over it.  I'm looking for construction details.  I am driving a Suburban and a lot of roof to work with.  
This sounds crazy, but I think it would work very well.  Any ideas?

Thnaks,

Rick - N4NOO


Title: AH4 & 102" Whip - Roof mount
Post by: N8EMR on March 04, 2003, 08:00:32 AM
Lets look at this.. 102 plus a 6" or so spring is 108" or 9ft. Figure the vehicle is at least 5ft, maybe more, maybe a lot more if its lifted. So now your at 14ft.

What is your states limit for hight of a vehicle?


Title: AH4 & 102" Whip - Roof mount
Post by: K0BG on March 04, 2003, 09:45:58 AM
The top of my mobile antenna is right at 16 feet (look up my call here on eham.net for a pix). It hits a few low wires in town, but that's all. And it clears most gas station overhangs. But.... there are places in the US where you can not have an antenna this high (long). Not so much for the local laws, but because there are too many low bridges, etc.

As for the whip and AH4, it works fine except on 40 where you really need a little more length or some sort of loading to make it work more efficiently. I have 4 articles published here on eham.net you might want to read (4407, 4424, 4425, and 4623).

Alan, KØBG


Title: AH4 & 102" Whip - Roof mount
Post by: KA5S on April 03, 2003, 09:56:24 PM
I've used an AH2.  I found little difference with it strapped inside a hatchback window or setting beside the whip on the roof. (That may be because the additional lead wire also radiated.) However, it was not particularly successful on bands below 14 Mhz; the whip was just too short, and the tuner losses too high. Not that it wouldn't LOAD; I've set a ball mount on FIRE loading a short mast on 80. It just wouldn't radiate worth a darn.

Cortland