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Author Topic: SO-239 Mount fo ATAS-100 on Small Car  (Read 2246 times)
KR0L
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Posts: 3




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« on: March 26, 2012, 05:29:42 PM »

Hi folks,

I bought an ATAS-100 at a good price from a friend.  It is a compromise antenna, and I knew that going into it.

I drive a small car - a Hyundai Elantra GT Hatchback (2002).  I've been struggling to find good ways to mount this thing, and mostly failing.  I've carefully perused http://www.k0bg.com/antmount.html and still am stuck.  The vehicle is small, lightweight, and has "European" styling - almost no flat surfaces on the body.

The ATAS-100 has a recessed PL-259 connector and requires an SO-239 base.  I'm guessing this is because the control for the screwdriver doesn't use a separate control connection, but I'm not sure.  Anyhow, the two main options I'm coming up with are a hitch mount (or some similar mount that would be low and rear, and a side mount of some sort.  K0BG explains repeatedly why a hitch mount, or other low-rear mount, isn't a good idea (poor ground plane).  Other hams also suggest that a low-riding antenna will radiate poorly towards the front of the car.  KB0G suggests a ball mount for the side.  Trouble is, I can't find any ball mounts with SO-239 connectors.  I suspect that the occasional 3/8-to-SO239 adapters I've seen won't work because I'm guessing the ATAS-100 does really require both legs of the SO-239 to be connected to the radio to drive the motor.

I live in Kansas.  It is not uncommon to have a 40MPH headwind while I'm driving down the Interstate with a 75MPH speedlimit.  That's a 115MPH wind load.  I ran a simple Hustler vertical for 20m on a mag mount, which blew off my roof recently.  I have very limited options for lip mounts on this vehicle anyhow, and I have no doubt that what K0BG said about lip mounts causing damage is true.  I want to avoid mag mounts, even the 3-magnet ones, based strongly on my experience with them and K0BG's advice.

Anyone got some ideas for me?  I'm pretty much stuck on something good for this car.
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NA4IT
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« Reply #1 on: March 26, 2012, 06:41:01 PM »

Look at Comet or Diamond mounts. Both have the SO-239 connection, and in different mounting styles.
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KR0L
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Posts: 3




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« Reply #2 on: March 26, 2012, 07:28:25 PM »

Do you mean lip mounts, or some other type?

Thanks for the tips.
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AC4RD
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Posts: 1235




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« Reply #3 on: March 27, 2012, 04:20:11 AM »

 K0BG explains repeatedly why a hitch mount, or other low-rear mount, isn't a good idea
Anyone got some ideas for me?  I'm pretty much stuck on something good for this car.

"Low and at the back" may not be your best choice, all the experts agree.  I drive a tiny econobox ('06 xB) and park in a low garage--this made mounting a HF antenna rather tough.  I spent several months experimenting with different antennas and mounting options, and (FOR ME; YMMV) low and at the back was far and away the best of the options I tried.  I'm using the "towing eye" as an antenna location--it screws into the rear bumper area.  Photos at http://www.duke.edu/~kuzen001/ac4rdmobile.htm     I tried shorter antennas mounted higher, but the best mobile performance I came up with was this, and it's working relatively well for me.

I had hamsticks on my previous car, a '00 Impala, using a trunk-lid mount, and I never had any damage or problem with those mounts--which is not to say they won't cause damage in your case, of course.  But they didn't hurt my Impala, or the Bonneville I had before that.

Good luck!  
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WX7G
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« Reply #4 on: March 27, 2012, 05:54:14 AM »

I have an ATAS-120 on my Smart Car. It's mounted at the roof line and works quite well.

The radiation efficiency on 40 meters is 10% and on 20 meters it's over 40%. I'm a DXer and work CW DX while driving to and from work.

The antenna is mounted on a Diamond K400C SO239 mount. This works nicely and I remove the antenna every night to park in the garage. As such the antenna has been though 500 on/off cycles with no problem.

This antenna is OK on 40 meters and on the higher bands is very good. The 10% efficiency makes my 100 watts into QRP and working Japan from Utah only possible during very good propagation. On the higher bands it will hold its own against home station verticals and dipoles.

The near-instant band changing is nice for me because I QSY every few minutes. I'll start at 10 meters and work my way down to find the band with the best DX propagation. I'll also fish out a band for DX then go to another band.
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M6GOM
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Posts: 901




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« Reply #5 on: March 27, 2012, 11:50:45 AM »

European here....

Look at the side of the car. Put it in the middle of the roof in line with the middle of the rear door window...

That is about where I put my Little Tarheel II with a 60" whip which has more weight than your ATAS and that was fine doing 80MPH into 60MPH headwinds.

I wouldn't even entertain putting a HF antenna on a magmount other than on a triple magmount with two magnets at the front.
« Last Edit: March 27, 2012, 11:53:06 AM by M6GOM » Logged
VA3WXM
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Posts: 277




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« Reply #6 on: March 28, 2012, 09:10:49 AM »

A friend of mine had a spare permanent NMO mount on the trunk of his car and he uses an NMO-SO239 adaptor for his ATAS-100.  I personally think that's a lot of antenna to be supported by an NMO but he hasn't had any issues yet.
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KR0L
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Posts: 3




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« Reply #7 on: March 28, 2012, 11:51:19 AM »

I'm curious, M6GOM, what kind of mount you used (or are suggesting) for that.  On my car, this location will cause the antenna to permanently lean backwards, though that probably is the only part of the roof I'd think might be strong enough for this.
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N6AJR
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Posts: 9908




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« Reply #8 on: March 28, 2012, 12:25:44 PM »

On my car I use the Diamond K 400 C mount which is a trunk lip mount.  it goes on the side of the trunk lip, not the par up behind the rear window.  I also tie a piece of thin fishing line  to where the antenna whip meets the base and it hooks on the coat hanger hook inside the back to give a bit of strength against the push of the wind.  It works OK, and I run a piece of braid from the shield side of the mount to a bolt under the car side of the trunk lid  hinge to give it a solid ground, as the trunk lid "floats" a bit at speed, and the hinges are not always in ground to the car, so the strap helps.

on my truck I just drilled a 1/2 inch hole through the bed rails, and put in a 2 inch long through the wall type so239 with a couple of large fender washers  for strength, and screwed the ATAS on that.  It is not the best antenna in the world, but it does OK for me. the convenience of it and the auto tune is slick. good luck and enjoy.
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