Manual ATAS antenna and controller

I have been using a Yaesu ATAS-100 mobile antenna for a long time with good results on both my old Jeep Wrangler and now my Toyota Tundra. Unfortunately Wisconsin winters can be harsh and the salt used on the roads leads to significant corrosion of everything, including the aluminum antenna body. The bottom 1cm of my antenna tube was swelling and turning into white powder.

I disassembled the whole thing with only some difficulty but needed to replace the aluminum body tube. Yaesu parts did not have a body tube available so off to the suppliers on the internet.

I was able to order a 16" long, 1.25" OD x 0.049" Wall x 1.152" ID Aluminum Round Tube 6061-T6-Drawn from -- it was the closest fit available. It's just a tiny bit looser than the original tube but entirely acceptable.

I cut the tube to the same length as the original and used a lathe to index the six holes at the correct distances around and re-assembled. It all fit! After that, I disassembled and gave the body two coats of flat black krylon. Not as nice as the original anodized aluminmum finish but plenty good for me.

Next is a controller as I want the option to use this antenna with a non-Yaesu radio. I had acquired an ATAS-120 replacement for my truck so this antenna was spare, but not exactly saleable as the tube is close but not quite OEM.

The Yaesu ATAS antenna uses voltages on the coax to raise and lower for tuning, +12 to extend, +8 to retract. That's easily accomplished with a bias tee and a 8V regulator but I can't leave well enough alone.

The bias tee I built was designed by AD5X:
Build a 3-amp Legal-Limit Bias-T that Covers 1.8-230MHz
The parts were readily available from Mouser and I had a nice enclosure with connectors in my junkbox.

With the bias-T complete, I built a controller. The design is simple, a momentary SPDT switch selects between +12V and the 8V output from a 7808 linear regulator for raise and lower, respectively. And then scope creep happens. How can I tell if I'm at the end of travel? How can I tell if it's stalled? How can I tell if it's moving at all? Easy. Monitor current consumption. But how?

In the end I decided on a TI INA219 high-side current monitor with I2C output. That when combined with an Arduino Micro Pro and a 1x16 LCD already mounted in a J-box lid offered a convenient way to control and monitor the antenna.

Boards with the INA219 and shunt resistor are available various places including Amazon -- twelve bucks for five boards, shipped. Probably factory rejects but hey, mine worked.

Code is here:

Connected to the switch common pin, the INA219 is in the high-side of the output. Motor current consumption is displayed and indicates if a stall situation is detected. A red LED is included in addition to the "STALL!" warning. Additionally the INA219 reports voltage so I also indicate travel direction. Nothing is done to stop the user from continuing to apply power in this situation as the antenna drive has a coupler that allows for slip.

And that's it. A simple up/down controller with current monitoring.

This page last modified Tue Dec 21 19:31:24 CST 2021 by timc!

go back