Yaesu ATAS-120A – An “Easy Button”

Note: This is a trimmed version of my ATAS-120A failure article.

I bought my Yaesu ATAS-120A in 2007 after upgrading to a General Class Amateur Radio license. Being new to the HF bands at the time and operating while mobile, I wanted a multi-band antenna that was affordable and easy to use, yet still effective. “Easy to remove” was also on my requirements list since my weekday commute included a parking structure. While not the best screwdriver antenna, it’s very convenient and a breeze to learn. The ATAS-120A, shortened to “ATAS” from here onward, was and continues to be in a class of its own since it doesn’t use external control wires or require a separate tuner. Simply screw it onto a bonded SO-239 mount, connect its feed line to a compatible Yaesu transceiver, and then press the transceiver’s “TUNE” button… the rest is automatic. A mobile antenna system can’t get any easier to use than that!

Lowered and ready for high-speed travel!

Is it effective? I was making contacts and getting good signal reports, which some say is not enough to prove that the ATAS is a good antenna. Making contacts to both Europe and South America seemed “effective” to me! I even made a weak contact to Hawaii from the deck of a car ferry on the Delaware Bay! Could my signal have been better? I suspect it could, but the ATAS was getting the job done for this beginner! This photo shows my ATAS mounted to a Diamond K9000 motorized antenna mount that enables me to lower the antenna at highway speeds or when entering height-restricted areas.

Mounted to an NMO adapter, but the roof flexed more than I preferred…

The ATAS has been both praised and criticized over its life cycle. Those who love it appreciate its ease of use while some critics say that it’s “just a tunable dummy load” and that nearly anything else is better. Calling it a dummy load is an exaggeration, but is “nearly anything else” better? That may be true with the assumption that there’s plenty of space to mount said better antenna. I’ve always driven small cars; so, real estate is at a premium. Apartment dwellers also have mounting restrictions; and home owner’s associations are almost unavoidable near cities, especially in newer developments. As a result, there’s something attractive about employing smaller multi-band antennas.

There is a drawback that’s worth mentioning: Yaesu’s only published power rating for the ATAS is “120 watts A3J.” In short, “A3J” is Single-Sideband (SSB) mode. I think 120W seems great when considering that most HF transceivers output 100W. However, if you look at the specs for some other screwdriver antennas, you’ll see that their ratings for AM, FM, and data are ~25% of their SSB power ratings. I usually operate at 50W in FT8, but I don’t think that alone is what caused the demise of my ATAS. Instead, my own operator error led me to transmit 100W digital through my ATAS during an extended Winlink session. The result was the melted mess shown in this photo. See a full write-up here. Today, I don’t exceed 30W when operating on digital modes.

Antennas being lowered for entry…

Are there better antennas and better mounting solutions than what I have here? YES! But that’s not the point! My K9000-mounted ATAS gets me on most HF bands while still being able to squeeze into parking structures and other height-restricted areas without the need to stop and store the antenna. Not wanting to stop sounds lazy, but the truth is that I sometimes don’t know when I’m going to enter a height-restricted area; plus, it’s not always possible to stop and remove an antenna without being a nuisance to other drivers. An ATAS mounted to a K9000 mount mitigates the vast majority of surprises… I like that!

Inset photo shows threaded hole for braided bonding strap…

“How did you ground your ATAS?” may the most common question I receive about my antenna’s mounting. The ATAS-120A has a reputation for its need of excellent grounding or bonding. I went overboard on my first car to carry an ATAS (see the photo album below), a little less on the next car, and my current car is unorthodox to say the very least. My roof rack rests on non-conductive landing pads. My bonding path from the ATAS to the chassis starts at the SO-239 mount, connects to the K9000 mounting point via braided cable, travels forward along a Superstrut channel, then attaches to a factory threaded hole in the front door jamb via separate braided cable. The Superstrut mounting hardware pierces to metal inside each crossbar; so, the entire roof rack is bonded at each front door.

I have a Scorpion mobile HF antenna, too. It covers 80-10m and accepts full legal power. See a comparison between the ATAS and Scorpion here. The Scorpion is a great antenna, but it’s not always practical, especially if I’m carrying cargo or need a shorter load. I leave it at home when I’m on those kinds of voyages. The ATAS fills most of my HF needs for one simple reason, using an adaptation from another saying: “The best mobile HF antenna is the one that you always have and will carry.” I’ll continue to use the ATAS for impulse opportunities and the Scorpion for planned events when I want a little better performance.

Some Things Never Change,

Scott

Bonding for the ATAS.

K9000 mount and ATAS bonding…

Using flashing material to bond the trunk lid in my old 1998 Jetta…

I used a more simple approach for bonding the trunk lid on my 2014 Jetta…