Recently, I bought a Yaesu FT-857D and an ATAS-120 antenna. A couple of weekends ago, KB7YWE and I installed them in my truck. Well, mostly in the truck, as we used the radio from a resting position on the passenger seat. Really, we just wanted to see how well it worked.

The Radio

The Yaesu FT-857D is an all-mode, multi-band radio that covers 160m-6m, 2m and 70cm. It emits 100W of power on HF, which is twice the power of my TenTec Scout. It also has the ability to control the automatic tuning HF antenna, which I’ve described below. The radio has a detachable face plate, making it easy to mount the radio in one part of the truck and use it in another, which should make it easier to find a place to mount it.

 

The Antenna

The Active Tuning Antenna System 120 (ATAS-120) is an antenna that can tune itself to the proper length for the frequency that the radio is trying to use. Essentially, you change to the band you want to use, press and hold the ‘Tune’ button, and the antenna will extend or contract to find the correct length of the antenna. It does this by minimizing the standing wave ratio (SWR), which you can observe on the graphical control panel on the radio. This feature is available from 40m-70cm (even though the 2m and 70cm bands use the antenna fully contracted). This works well for me, because I’m renting in a subdivision that has restrictions against antennas, making any permanent setup for the larger antennas impossible.

One thing of note, if you’re going to do an install of this of your own, you’ll need a diplexer. There are two antenna outputs on the Radio, and one antenna to attach for all bands.

The Installation

KB7YWE help me with the install. I’ve always consulted him for his expertise on these matters, because he’s great with amateur radio matters, and very skilled at working with cars (which I’m not).

The antenna mount was a trunk mount that is intended to attach to the lip of a car trunk. It pushes the Xterra hatchback slightly out of place, but that also makes space to feed the coax through the gap. Once we had the radio wired directly to the battery, we were eager to try tuning the antenna.

The tuning was very touch and go. Some bands that were supposed to tune didn’t. However, it was still really cool to watch. The radio has a graphical SWR meter, which you can watch change as the antenna becomes more closely matched with the frequency. To deal with the spotty performance, we decided to turn our attention to grounding. We attached the outer conductor of the coax connection to the screw that held the hatchback door supports. Then, we went back to the radio, and it tuned perfectly on 10m, 15m, 20m, and 40m. We were very happy.

Later, I tried 12m, 17m, and 30m. All of which tuned, but then the former bands did not. Adding a second ground, from the radio chassis to the car body, seems to have fixed this problem.

I still haven’t figured out where I’m going mount the radio in my Xterra. The most logical path seems to be removing the double height stereo from the dashboard, and replacing it with a smaller stereo (maybe one that plays MP3s from SD cards) and the Ham Radio. The downside to this is that I won’t be able to remove the radio and use it outside of the truck. With my current neighborhood restrictions, I do all of my HF from the truck anyway, making this a non-issue.

With this setup, I was ready (and really excited) for Field Day. Next post, I’ll talk about how that went.