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Author Topic: Trim Mobile Antenna Whip?  (Read 5871 times)
WT3O
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« on: June 16, 2015, 04:33:58 PM »

I have a mobile antenna question. I think I know the answer, but I wanted to see if anyone else had any thoughts.

I just got a new F-150 and want to install my FT-857 and ATAS-120 antenna. This year's F-150s are a little taller than previous years. If I put my ATAS-120 on the bed rails via a bed stake pocket mount, the antenna will be about 9 1/2 feet from the ground to the top of the antenna. I'd still like to go through drive thru (banks, fast food, etc...), but most clearances are about 9 feet. I was thinking of cutting off about 8" of the ATAS whip and let the loading coil pick up the difference. I can't imagine 8" would make a huge difference on 20M or 40M (or even VHF with the auto-tuning antenna). I know the name of the game is to have a larger whip, but I want to mount my antenna on the bed rail and still use drive thru, so it seems my only choice is to shorten the whip?

Does anyone see any problems (other than a slight performance decrease) with cutting off a few inches of the whip?
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K0BG
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« Reply #1 on: June 17, 2015, 05:45:34 AM »

The ATAS is the lossiest, remotely tunable antenna made. Shortening it up, just adds insult to injury. And, you won't be able to work 40 meters.
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K5LXP
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« Reply #2 on: June 17, 2015, 06:31:26 AM »


I don't get why you'd want to trim a whip for clearance.  The whole point of a whip is to flex and move if an object is encountered.  So what if the whip touches something as you go - that's what it's made for.   Factor in that this idea would negate 40M operation as K0BG mentioned, and you make the ATAS less useful than it already is.  The ATAS isn't a barnburner on 40 but it is a testimonial that QRP works, and I've managed a bit of DX on 40M over the years I've had mine.  Nothing like driving down the road and hearing a JA, VK or UA come back to you running such a modest antenna.


Mark K5LXP
Albuquerque, NM

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M0GVZ
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« Reply #3 on: June 18, 2015, 09:59:06 AM »

Buy a Little Tarheel 2. Mine is on the top of my car with a 76" whip on. Went under a 2metre low height barrier in France yesterday with a clearance of less than a couple of feet above the Tarheel Base after I forgot about the antenna as I never worry about it.  The whip just bent and then sprang back once I cleared it.

Mine hits all kinds of overhead objects and is still OK after 3 years.
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N5UD
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« Reply #4 on: June 21, 2015, 08:13:21 PM »

Get a Hnak Breedlove brass quick dis-connect. Place at top of coil and on the whip. Remove the whip when going into parking garages.

Dave N5UD
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WT3O
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« Reply #5 on: June 22, 2015, 04:13:40 AM »

Get a Hnak Breedlove brass quick dis-connect. Place at top of coil and on the whip. Remove the whip when going into parking garages.

Dave N5UD

Thanks for this info. I think I'll head in this direction.
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WA9CFK
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« Reply #6 on: June 29, 2015, 07:35:58 PM »

My old Hustler is 9 1/2 feet high. I have a small spring below the coil for when I forget about clearances.
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G8YMW
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« Reply #7 on: July 01, 2015, 03:19:23 AM »

My old Hustler is 9 1/2 feet high. I have a small spring below the coil for when I forget about clearances.

That wouldn't work with an ATAS a it has the SO239 mount with the DC power fed through the coax
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73 de Tony
Windows 10:  Making me profane since March 2017
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