HF Mobile Installation
HF Mobile Installation, written for Dodropin.org by KA5YIX. 2/19/12 What is a ham to do when living in a home with antenna restrictions? After experimenting with stealth wire antennas, I decided to focus my energies on an effective and enjoyable HF mobile installation. I scoured the Internet, phoned vendors, and walked a couple of hamfests, until I found the best equipment and methods for my needs.
HF mobile is a series of compromises. These may be minimized by selecting the appropriate equipment and proper installation. Some of these variables are dictated by your choice of vehicle. I drive a large SUV. Fortunately there is sufficient space for equipment and wiring. The truck has a high output alternator and upgraded battery, which were part of a cold weather option from the dealer.
Prior to the installation shown in this article, I ran HF mobile in a small 4 door sedan. It was a completely different experience, requiring a compact radio and small antenna. The radio was a Yaesu 857D, with Hamstick mono band antennas on a triple magnetic mount on the roof. The feed line was running out through the passenger window (creating noise and water leaks), and the mount was damaging the roof. I made contacts, but I was not enjoying it. I could only work the strongest stations, and the built in speaker was hard to hear. Carrying a selection of Hamsticks was a challenge, and I had to stop the car to change bands.
Based on those experiences, I knew what I wanted to do. First priority was a safe and clean installation, something presentable to my XYL and other passengers. I wanted to improve receive and transmit performance, and have easier band changes. Finally I wanted to remove the antenna at any given time, due to parking lots and other overhead obstructions.
OK, now on to the good stuff! What radio, which antenna? Radio choices were narrowed down to the Icom IC-7000, and the Kenwood TS-480 series. Both are excellent, with the IC-7000 boasting a large color display, 2M and 70cm, and powerful filters. In contrast the TS-480 has a rather plain display, and lacks VHF and UHF. The TS-480 is available as two models, the SAT version which includes a built in tuner, or the HX which eliminates the tuner and increases the output power from 100 to 200 watts. That might seem like a tough decision to make, but as you will see a built tuner is not required. I selected the Kenwood TS-480HX and it works very well for my application.
Antenna selection and mounting is the most important part of a mobile installation. I chose the Tarheel model 200A-HP. http://www.tarheelantennas.com/model_200a_hp_package The 200a is a screwdriver design which covers 80 meters to 12 meters (3.4 to 28 MHz), and in my experience works on 10 meters with SWR approximately 2.5 to 1. It is a large antenna with a maximum height of 12 feet. It is too heavy to consider a magnetic mount; this 8.5 pound antenna requires substantial support. Initially a friend was preparing to weld a mount to the underside of the frame. In the end I used a rear hitch mount, due to the convenience and ease of removal.
So how did this all go together? The first thing I addressed was power. A local shop http://www.installer.com/ ran 6 gauge stranded copper wire from the battery to the driver seat. The wires are fused at the battery. I terminated the power leads under the seat with 75 Amp Anderson Power Poles, http://www.powerwerx.com/anderson-powerpoles/housings-contacts/ with 60 Amp fuses on both positive and negative leads. Next in line is a RIGrunner http://www.powerwerx.com/powerpole-power-distribution/ with fuses on each outlet. The wiring and power distribution fit nicely underneath the driver's seat, along with the TS-480HX and a Kenwood TM-V71A dual band radio.