I’ve had my Yaesu ATAS-120A antenna for a couple years now. In that time, I’ve had a few instances where I would swear that the thing is broken and needs to go back for repair. Luckily, that small voice, inside of me says “whoa, let’s check some things first”. The voice is usually correct, by the way. The antenna works like a champ.
The ATAS-120A is similar to the Tarheel screwdriver antenna, but for several hundred dollars less. It has a motorized element, and changes length in response to being tuned by a compatible radio or aftermarket controller. My FT-891 matches the antenna using either the tune button, or the up/down buttons on the radio menu.
MFJ sold an outboard controller (MFJ-1925) compatible with this antenna. It allowed you to use it with radios other than the ones it was designed for. I haven’t played with the MFJ controller, and have no plans to.
If my antenna begins acting “Squirrelly”, I immediately think the worst. But, the problem so far has always been something besides the antenna. So, here are some things to look at if your ATAS-120A refuses to tune.
- Wait! When you push the tune button, and nothing happens, wait! Don’t be impatient. Occasionally I’ve had to wait a moment for the antenna to think before it keys the radio and actually starts moving. I don’t know why mine does this, but it does.
- Check your grounding! Is your antenna mount grounded properly? Are you using an aluminum bracket and attaching a plated barrel connector to it? Dissimilar metals can be a real pain, when corrosion begins to set in. The joint becomes resistive and starts giving weird symptoms. The ATAS antenna may refuse to tune, but a good whack to the side of it will get it working (Don’t ask how I know this). So, every once in a while it is a good idea to do a PM on your mount. Take it apart, clean up all surfaces with a non-metallic scouring pad, then re-assemble being sure to apply a fresh film of Penetrox.
3. How is your feed line? Do you need new connectors? Are they good & tight to the radio, and the antenna? I do as tight as possible by hand, and it seems to work well. I’ve found that it doesn’t take much resistance in the antenna system to limit the amount of current going to the antenna.
4. Lastly, how’s your battery voltage? My experience has been that when my battery voltage drops to the low 12V range, it introduces some weirdness in the antenna operation. The ATAS will tune OK when manually raising or lowering it via the menu options, but will not work when activated via the Tune button. Maybe it just doesn’t have enough power to tune properly? I don’t know.
My system usually consists of a Yaesu FT-891 driving the ATAS-120A antenna. The power source is a LiFeP04 battery. For the most part, everything works as designed but once in a while, the ATAS – 120 a will become a bit stubborn. In every case, the fix has been something on this list.
I sure don’t consider myself an expert on these antennas but when you’re a couple of hundred miles from home, and you need one more contact to make a valid activation, you become an expert on field troubleshooting.
And that is it. I wish you safe travels, and trouble-free activations. 73 DE WG8X