Yaesu FT-857D Mobile Installation

Over the years I have tried to find a solution to get a decent HF solution into my car. I started with a Radio Shack HTX-10 10 meter rig, but the sunspots and mag mount antenna did not yield much of anything. I also had an Icom 706 hooked up to a ham stick / tuner, but that didn’t work very well either. Since moving a few years ago, I have been unable to install anything at home due to antenna restrictions so HF operation has been impossible. I even tried a Yaesu FT-817 QRP rig indoors with various antennas, but there was just too much noise to hear anything. Was I completely out of luck for HF?

A few weeks ago I decided to sell my FT-817 and accessories to help fund a new radio/antenna. I ended up choosing the Yaesu FT-857D and the ATAS-120A mobile antenna. Now I know there are limitations to this antenna as well as it being a little more expensive than a hamstick, but I had to give it a shot. Everything in the past has been a painful time consuming process just to get on one band, let alone trying to switch between bands quickly. I wanted something that would be as easy as turning on the radio and getting on the air. Would this setup disappoint me as well?

Diamond K400C trunk mount
Diamond K400C trunk mount

I chose the recommended Diamond K400C trunk mount which doesn’t require any drilling. I wasn’t sure how well this mount would work as all my other mounts have been magnet mounts. Obviously with this antenna being a little heavier and taller than most dual band antennas, a regular mag mount wouldn’t work. I installed it on the drivers side of the trunk and ran the cable in through the backseat with all my other cables. As for the radio, I mounted on the floor board behind the passenger seat with my other radio. I use the word mounted loosely as it’s really just velcroed but it’s not going anywhere.

The radio came with the separation kit, so that saved me some money. I currently have the faceplate mounted on a vent mount above my XM radio on the dash. I’m really not impressed with this type of mount as it moves around too much, so I will look for a different solution. The microphone and speaker are loosely mounted so I can hide them away when I’m done using them. The power cord is run directly to the battery through the firewall.

Yaesu ATAS-120A
Yaesu ATAS-120A

When I first turned the radio on, I was a little overwhelmed by all the menu settings. However, after thumbing through the manual I became a little more familiar with them. I found the setting to enable the ATAS-120A antenna and hit the tune button. The first time you run it, it takes a few minutes to initialize but after that it’s pretty quick. I flipped through all the bands and it was able to establish a 2:1 or less SWR every time even on the WARC bands. (according to the built-in SWR meter anyways) I tuned around the bands and was hearing numerous signals, so that was another promising discovery.

I decided to visit a local park about 8 miles NW of town which would hopefully get me away from most of the noise of the city. The Michigan QSO party was going strong and I thought I’d try responding to one of them just for kicks. NV8N was coming in pretty strong on 40m so I threw out my call running 50 watts. He heard me on the first try which threw me off guard as I had no idea what the exchange for the contest was. 🙂 Luckily he was patient and explained what info he needed from me and like that my first contact had been made! Not too shabby I thought.

I continued scanning around the bands and landed on 17m. I heard ON4HIL calling CQ, so I tried calling him. It took numerous tries as others were calling and the band was up and down, but I eventually got him. He gave me a 5×2 report and said that wasn’t too bad for my 50 watts. After the brief QSO, I looked up the prefix on my phone and discovered he was in Belgium! I know for most hams with big stations at home this would be boring, but for me to work another country in the mobile with 50 watts is pretty darn cool to me. I was actually quick enough to record the QSO on my phone just so I had proof of the contact.


Later that evening, I went for a drive and tuned around on 40m. I noticed that the Ontario QSO party was also going on. I managed to work several stations while I was driving, so that was pretty cool despite the increased noise from the car. I managed to snag a recording of the QSO with VA3SWG.


I know it’s just a handful of contacts but I’m really impressed so far. The ability to hit a button to tune the antenna and get on the air in a few seconds is pretty awesome. I can’t wait to try it out this summer and see what other contacts I can make. 73!

9 thoughts on “Yaesu FT-857D Mobile Installation”

  1. Nice article. I hope you have better luck with your ATAS-120 than I did. I got mine at Dayton in 2010. Its been on the car for 3 months. Its already stopped tuning. You can hear the motor running inside the antenna but it doesnt tune anymore. I’m pretty disappointed with that fact. Its off to Yaesu for repair now. I think I might look into a Tarheel next time? 73!

    • Sorry to hear about your antenna dying. I hope Yaesu is able to fix it quickly for very little money. (still under warranty maybe?) Knock on wood, mine is still hanging in there though I don’t use it as often as I should. The hassle with all the other screwdriver antennas made the ATAS-120 perfect for my needs. I just need to setup a remote operation so I can use it from inside the house.

  2. Stan, thanks for publishing this article. I too have a relatively new 857D, ATAS-120A, and K400c. Although I have had some issues with my installation, I have found that Yaesu technical support is very helpful and for Zac, W9ZTH, I recommend that he give them a call. I may have to send mine to Yaesu and have them swap it out, but I love the set up. Are you running all bands through the ATAS? If so, what duplexer did you use?

    John K0JMS

    • I usually tried to operate in a stopped position with the engine shut off. I’m not sure if it’s possible to remove all engine noise. Check out this site for some tips on noise reduction methods.


  3. Just received my 857D and ATAS 120A yesterday and am anxious to get it installed and put my FT-7900R in the house as a base. I’m looking to use the ATAS 120A for all bands and get rid of my dual band VHF/UHF mag mounted antenna.

    Gigaparts told me I needed a duplexer, so I got one from them. I’m a new ham, so I’m not sure why you would use a duplexer if you are using one antenna? It allows better band separation? Can anyone enlighten me? Many thanks, 73 Joe

    • Which antenna did you get? I believe the 6m section is on the HF antenna connector. Otherwise I don’t understand why you would need the duplexer.

    • 857D is both HF & UHF/VHF which use 2 connectors on the radio hence the need for a duplexer. One antenna into 2 ports. I recommend Diamond CF-706.

  4. I bought a used FT857D with the Atlas 120 for $840. I need to make a short cable for the faceplate, or mount it remotely, & I will need a switch or a duplexer. The rubber weather guard is missing, but I have some Kearney Spec Aqua Splices that will work, and probably do just as nicely. I hope it works. I used it to receive some simple broadcast AM, but I am going to screw it to my air conditioner on the roof for the house, for counterpoise, (it is hooked to the electrical ground, & water pipes are right there, plus I jumpered the duckwork boot to ground ages ago, so that mass of ductwork will be there too. I will probably use a tilting motorized mount for my truck, and a magnet or trunk lip mount for the car. It says in the manual I may need to switch from the HF antenna jack to the VHF/UHF. I already bought a ready made cable like a dumbass. I should have bought a 500 ft spool of RG8 for $169 shipping included & a shipload of connectors. I have the compound leverage & hydraulic crimpers for telco, cable, electrical, etc. etc. and can make any cable from an RJ11 to microwave, to a camlock 500KCMIL parallel power cable for load testing 500KW generator sets. The guy sold me an Astron 35 watt PSU for $80, & it Dynaload tested steady up to 30 amps, which is more than I need. I am new to ham radio, but I have been blackening outlets since I was 5 years old. I am really good at it now, and build guitars, guitar amps, effects racks, with MOSFET switching, power supplies, audio gear, audio signal processing, analog, digital & hybrid.


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