Last Modified: Wed, December 9, 2009
Contents; Basics; Doing it Right; Antennas & Things; Equipment Placement Caveats; Odd & Ends;
If you don't take time to do the job right the first time, how are you going to find time to do it over?
I suggest using the seven Ps; Proper prior planning prevents piss poor performance. But I must say, in almost every mobile installation I have ever done, there ends up being something I could have done better. In other words, what seemed like a wonderful idea up front, wasn't so good after the fact. This is of extra concern for those who have never done a mobile install before. Hopefully, the information presented here will minimize the amount of rework.
All of the photos that once appeared in this article, are now posted in the Photo Gallery, along with others from the same install. They are listed in alphabetical order, and by the call I received them from. Some may be long in tooth, but I still think they are a valuable resource.
Anyone planning on installing radio gear in their vehicles should read (at least) the following articles: Wiring, Bonding, Noise ID, Antennas, and Antenna Mounts.
There seems to be a lot of misinformation about installing amateur radio in vehicles with respect to warranty and electronic interference issues (RFI). Contrary to anecdotal information found across the web, no automobile manufacturer prohibits the installation of radio gear, amateur or otherwise. Nor do any deny warranty claims on vehicles so equipped. In fact, they offer guides on proper wiring. Here at the ones for Ford, and GM. The ARRL web site has information on other makes, here.
Perhaps there could be a case made wherein factory wiring was used and a fire resulted, but even that scenario would be hard to legally support. The point being, if you follow the recommendations herein, you'll never have a warranty problem. This said, there have been instances where dealerships have refused to work on vehicle (warranty or not) because the radio and/or ancillary hardware made access too difficult. Their position is easy to understand, especially if the problem at hand is being warranted. The best way to handle situations like these, is to discuss the issues with the dealership personnel first!
If there is but one theme to follow when doing any mobile installation, it is this: Safety. Far too many amateurs get in too big of a hurry installing their mobile equipment. As a result, their wiring is haphazard and improperly fused; their transceiver mounting is inconvenient or mounted too near an SRS device, and thus very unsafe; and their choice of antennas and mounting schemes are also suspect. Please! Take time to plan your installation, and you'll be rewarded. Do it wrong, and you'll end up with the proverbial Excedrin® headache.
Make sure you notify your insurance company and/or agent that you have installed radio gear in your vehicle. In some cases, the notification must be in writing. Most of the time, coverage riders are not necessary, but this is not a given. It's best to check first, not later. By the way, insurance companies generally will not cover radio equipment that is not permanently installed. This rules out mag mounts among other temporary mounting schemes.
Installing amateur radio gear shouldn't be a haphazard proposition, but for some amateurs it is. The use of Velcro®, double-sided sticky tape, suction cups, bungee cords, magnets, wedged in blocks of wood, and rubber bands are all prescriptions for disaster. Not one of us wants to be involved in a vehicle crash, but statistically one in seven will be at sometime in their lives. A minor knowledge of high school physics is all it takes to understand what damage an unsecured remote head or handheld can do during a crash. My advice to you is simple; please take your time, and do your installation right the first time.
In case you missed the point, safe operation is absolutely the number one priority when operating mobile. It should be obvious then, that safety needs to be a first thought, not a latter one. If there is one point about safety that needs to be driven home, it where you mount your radio, or its remote head. The top of the dashboard is not it! Modern Supplemental Restraint Systems (SRS or airbags) virtually cover the whole top of the dashboard. Any hardware so mounted will be flung far and wide when the SRS goes off (see below).
Where ever you mount the your radio or remote head, it should be within easy reach, and easily viewable. However, these two attributes can be mutually exclusive if the mounting isn't well thought out afore hand. Speaking of mounts, don't buy one, and then try to figure out how or where to mount it. That should be done first, and then a suitable mount selected based on the established criteria.
While I realize some folks don't like to drill into plastic interior pieces, if you plan well they won't be easily visible once the radio is removed. The photo at right is a good example. The flexible goose neck is screwed down inside the cup holder. Once the rubber protector is replaced, the holes will not be visible. Note that the controls can be adjusted while resting the forearm on the top of the console. This is an ideal situation for obvious reasons.
Speaking of positioning, it's tough finding room for all the requisite goodies, even microphone hooks. This drives some folks into using the foot wells to stash gear. My word on that is, don't! If you have to resort to using the foot well, maybe you should ask yourself it that ancillary goodie is really needed.
As noted above, proper planning is a necessity in just about every facet of one's life, and installing a mobile setup should be one of them. Unfortunately, that's not always the case. I've seen some horrible installations, and that's one of the reasons I haven't posted every photo I have received. I even have one of a mobile install where the head of an IC-706 is mounted in the center of the steering wheel, directly atop the SRS!
The left and right photos are of a Ford Escort belonging to a WAØ from St. Louis, MO. Believe it or not, most of the radios work, and are hooked up to antennas. He brings the car to the Dayton Hamvention® each year as a joke, although a pathetic one. While you might chuckle, some I've seen aren't much cleaner, or safer!
Here's something to think about before you buy an antenna, or at least your next one. The vast majority of e-mails I receive deal with RFI issues. The on-board devices affected are, well, all over the board. However, there are two common threads that crop up far more often than any of the others.
The first one is stubby antennas. There are currently five manufacturers I'm aware of, but there could be more. Folks buy them because they're unobtrusive, and apparently easy to mount. The most common mounting method seems to be the Diamond® K400®. The K400® series is an adjustable trunk lip mount, typically supplied with a 6 foot long RG174 type coax cable terminated in a crimped on PL259. Regardless of the advertising hype, the lip of an average trunk has enough flex that the mount needs to be retightened quite often (after about every trunk closure). Note the bent sheet metal in left photo. This type of repair is much more costly than filling a hole.
Remembering that the coax shield needs to be securely connected to the body of the vehicle (which acts as a ground plane), when it loosens, common mode currents flow over the coax with abandon! A separate ground strap isn't a cure. Even when the coax connection is secure, there will be more common mode currents than there would be if a full-sized antenna were mounted in its place. Overcoming this problem is not an easy task.
All remotely controlled HF mobile antennas will have RF flowing over their motor leads when transmitting. The basic reason is, the motor operates above RF ground. Therefore, the leads have to be bypassed (RF choked). The Antenna Controller article has a complete description about the requisite chokes. Again, the level of RF on the leads of stubby antennas are much higher than a full-sized one, all else being equal. Add a little insult by the mounting method mentioned in the previous paragraph, and RFI issues abound.
There must be an unwritten law someplace, that says you must have a wattmeter attached to your radios at all times! At least you'd think so by the number you see. I know of one mobile install that has seven, separate wattmeters! The true fact is, you might need one to set things up in the first place, but mounting one permanently is a waste of space. The one built into the radio is enough, and if there is something amiss, having the wattmeter in-line isn't going to help you fix it.
There is one meter to have on board, and that's a voltmeter! Those built in to some GM vehicles are nearly worthless. The one shown is a Martel Electronics QM-100V, two wire unit, and it's about the size you see here. If the voltage drops down below 10.5, and you might be in trouble!
There are several places in the interior of a vehicle which should be avoided and/or where extra care should be exercised. One of those is under the seats. It is not uncommon for the side Supplemental Restraint System (SRS or airbags) impact sensors to be mounted within the seat(s) framework, and in some vehicles, the side impact airbags themselves. These devices are directly interfaced to their control system using secured connections. It is possible, albeit remote, to set off an airbag if these connections are mishandled. Disconnecting the vehicle's battery is not a workaround, as these systems have their own internal power source!
The top of the dashboard is another poor mounting location. As noted above, modern SRS devices virtually cover the whole dashboard area. It pays to remember that airbags are really not full of air! Rather, they're inflated by an explosive chemical, usually sodium azide, and expand at rated up to 200 mph, or about 300 feet per second! Anything in their way, no matter how securely they're attached, may be flung far and wide. You can get a better picture by watching this video. It is always best to mount radios (or their remote heads) below the center point of the dash fascia.
The underneath side of the package shelf (top trunk area) is also a poor mounting place, as it is the hottest part of the trunk area. Adding a fan blowing on the heatsink isn't going help either, unless it's fed with cool air from the vehicle's cabin (not very likely).
A less than satisfactory placement is an unused DIN slot in the dashboard. Although inviting, very few have adequate ventilation. Worse, some that do are subject to a direct blast from the heating system.
You might want to read the Wiring article too. As shown here, there are all sort of safe avenues for installing the requisite wiring out of site, and out of harms way. You just have to know where they are, so buy a service manual for your vehicle before you start your install. They're about $75 for most makes, and trust me when I say, it'll pay for itself on the first installation!
There are two other points about proper wiring. First, don't scrimp! The difference in cost between size #8, and #4 is minimal, and reducing voltage drop is a very worthwhile undertaking even when you don't run high power.
The other is, don't bundle up unused hanks of wire. While I realize some excess cabling has to be bundled (Icom remote cables for example), power cabling should always be shortened where applicable. Again, this minimizes voltage drop, and the likelihood of shorts and other maladies.
Here's a few things I've learned the hard way. Perhaps they'll help you as well.
There is always a place to properly screw down radios and/or remote heads. If you have to resort to Velcro®, double-sided sticky tape, and other temporary means, then you haven't planned your install properly.
Make everything as automatic as possible. This is one reason why I like the BetterRF antenna controller so well. Once setup, a single button push finds the correct antenna resonant point. No meters, no switches, just the existing Tune button on the radio. How much simpler can it get?
If you run, or plan to run an amplifier, bite the bullet and buy the automatic bandswitching option. The ALS-500 has one available, and the SGC and HL450B have theirs built in. Here's something to think about. No matter how careful you are, sooner or later you're going to transmit into the wrong bandpass filter, and the cost of repair will exceed the cost of the option. What's more, a manual control is just one more thing to find room for! All you really need is a switch and an LED to control any of them.
Speaking of amplifiers. If your future plans are to add one, now is the time to wire for it, not after you buy it. Remember, rework is always costly (time and money), and frustrating.
A lot of amateurs receive flak from the spouses about their amateur radio extravagances. The main reason is simply because of the haphazard methodology they're so used to seeing in other amateur-related venues around the house. I've learned that doing installations right is a mitigating factor in reducing flak from a spouse. When my wife first saw the installation of my new antenna, it wasn't flak I got. Her exact comment was, "It looks like it belongs. I'll bet it works as good as it looks." Indeed it does.