My Yaesu ATAS-120a Mobile / Portable Antenna Setup

I use the Yaesu ATAS-120a ,a 2 lbs screwdriver-type, auto tune antenna that is designed specifically to go with both my FT-897D and FT-857D, for both mobile and portable operations. It does a surprisingly amazing job for both.

Best DX so far: Mobile from the top of the Smokies to VP8, Falkland Islands – with 10 watts – even at the bottom of this sunspot cycle. I have received so many requests for info and photos on the ATAS 120 antenna, I’ve created this separate page. (This page gets a huge number of hits – apparently even the techs at Yaesu are recommending folks check out the page for ATAS ideas. Thanks, guys – very much appreciated!)

I use the ATAS with several different mounting schemes depending on where I am and what I’m doing. Below are several photos that show these various schemes. If you mouseover the photos in IE, you will see details about each photo (apparently, the mouseover doesn’t work with Netscape or Firefox so you might want to start up IE if you are really THAT interested in the details.)

• I use Budd’s Vertical Antenna Clamp and special SO-239 mounting kit for portable, picnic and balcony operation. This is a very good approach for very temporary operations. However, with the weight of the ATAS versus the much lighter weight Buddipole, high winds will blow the ATAS horizontal unless guyed.
• As with ALL of the portable operations and mounting approaches, the antenna ONLY works great with a tuned counterpoise. I am finding that a lot of the same issues and ideas that work with the BuddiStick apply to what I am doing with the ATAS-120 for portable operation.
• For radials (I know “counterpoise” would be more accurate, but you know what I’m talking about!), I use three conductor Radio Shack flat rotor cable with each of the three wires cut to a quarter wave for a different band. I usually just use one of these for three bands…but sometimes use two of these to THEORETICALLY give me six different bands. Reality turned out somewhat differently. Surrounding environment and metal….along with radial interactions and radial angles and end heights, change things from all those very precise quarter wave measurements. However, the biggest problem I have found is that just one of the six bands will not auto tune with the ATAS….usually 40 or 12 Meters, depending on the particular portable operation set up. (Side note: I have been surprised how well this thing seems to work on 40…much better than I expected.)
• I use the Diamond CRM mount for our balcony in the mountains. If you are looking for a permanent installation approach for your ATAS, this mount works great with a double barrel SO-239. I recommend one that is about 6″ long.
• I also use another of Budd’s Vertical Antenna Clamp mounting kit with a cheap $18 mini tripod from Wal-mart. I have found this particularly handy for operating portable in the mountains. Note that the mounting kit has to be drilled out to fit the 5/8″ double barrel SO-239. In my case, Bud himself was nice enough to do that for me after I emailed him my intentions about using it with a competitor’s antenna! (As a management consultant to companies all over the world, I’ve seen the insides of a LOT of companies. I have never seen one as good about genuine customer service and quality as Bud’s BuddiPole company. They should be a model for every small company to follow.)
• If you decide to use this same tripod, here are some hints: you will need to pop out the current mounting screw since it is too short for the mounting plate. I replaced it with a longer stainless steel bolt and wing nut. A benefit of this particular tripod is that you can adjust the legs so they are almost perpendicular to the antenna thereby giving a very stable base for the ATAS even when the breeze kicks up….especially stable if the legs are also extended and perpendicular! (In the photos below, the legs are not extended.)
• If you intend to balcony mount or tripod mount the ATAS, I recommend as many counterpoises as possible – with at least one cut as a quarter wave for each band you want to work. Click this Antenna Length Calculator for a quick way to know how long a quarter wave is for each frequency of interest.
• My first mobile contact with the ATAS 120 was a mutual 59 contact with Costa Rica with 20 watts sitting in the parking lot of our Florida condo about 5 minutes after installing the antenna with less than adequate ground strapping. Improving this strapping has greatly improved both reception and transmission. Oops, I should have taken some photos of the strapping too. Will add those photos later!
• For my mobile installation, I have been using the ATAS 120 with a Comet CP-5M trunk lip mount since a roof mount is more difficult with a convertible! However, I am finding that the CP-5 keeps coming loose with Interstate speeds between Florida and Tennessee – even using Loctite.
• I am relegating the CP-5M to my Diamond CR320a tribander VHF/UHF antenna since it has the same M mount. I have just bought, but have yet to install, the Diamond K400C for use with the ATAS 120. All reviews I’ve read indicate it is a much better mount for such a heavy antenna.
• Update: Having just completed a 2,000 mile round trip to our mountain home and back, I can now report with certainty that the Diamond K400C is a much better mount for the ATAS-120 than the Comet CP-5M. I used Loctite on both – but the design of the K400C is just stronger with no slippage whatsoever – even at 85 MPH speeds for multiple hours (it is a 15 hour trip from Clearwater Beach to Gatlinburg with almost 90% of that spent on Interstates at 70 plus MPH speeds.) I should note that the adjustment range for the Comet IS better than the Diamond for adjusting the antenna so it is vertical from all perspectives. Will add new photos of the K400C and ATAS soon.

Bottom-line: I am very pleased with how well this antenna works with all the different and varying uses shown above. Stay tuned for more photos, with more close ups of real life uses as I have time to take them!

73 / 72,

AA5FR