Last Modified: November 7, 2011
Contents: Caveats; Basics; Doing it Right; Antennas & Things; Equipment Placement; Odd & Ends;
There are several caveats with respect to wiring amateur radio gear in late model vehicles. They're listed in the Wiring article, and should be reviewed before the actual installation begins. These caveats relate specifically to vehicles which use Battery Monitoring Systems (BMS) and/or Voltage Quality Modules (VQM). It should be noted that these are acronyms used by Ford Motor Company, and other manufacturers may use different acronyms for these devices.
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?
Very few amateurs go out searching for a new vehicle with the idea of mounting an antenna on it. Typically, they already own a vehicle, and they decide to operate mobile. Either way, it always presents a problem in some fashion. Minivans, SUVs, RVs, Jeeps, station wagons, crossovers, and plastic-skinned vehicles present the greatest challenges. As a result, I receive a lot of e-mails asking me for suggestions about mounting all-things mobile. This article is an attempt to answer the questions. In the end, it might be a feeble attempt, as what I'm willing to do, isn't necessarily what everyone else is willing to do. Drilling holes in sheet metal, is a prime example.
Whatever your stance on drilling holes, the performance you ultimately end up with is directly dependent on how much time, and effort you're willing expend. Or spend, as the case may be. I must say, in almost every mobile installation I have ever done, there ends up being something I could have done better. 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.
The Photo Gallery's Other Installs album is a good resource for finding a spot to mount antennas, transceivers, and all manner of ancillary hardware. They are listed in alphabetical order by the call I received them from. In some cases, the calls have changed and/or the vehicle has been traded. If you're looking for a specific call, use the album's search function.
Anyone planning on installing radio gear in their vehicles should read (at least) the following articles: Bonding, Noise ID, Antennas, Antenna Mounts, Radio Mounts, and Wiring.
Speaking for wiring. Note the arrow in the photo at right. It is pointing at what's left of an accessory socket (cigarette lighter) plug, after it started a wiring fire. This is the exact reason why you should never, ever use existing vehicle wiring to power any amateur radio gear, no matter what it is!
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 wiring fire resulted as shown in the left photo (arrow is pointing to a accessary plug). 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.
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! However, don't believe them if they tell you radios aren't allowed; that's an untruthful statement!
If you've been reading the other articles on the web site, you'd know this important antenna mounting point; It is the metal mass directly under the antenna, not what's along side, that counts! Therefore, almost without exception, the best solution to this correlation requires drilling holes!
If there is but one theme to follow when doing any mobile installation, it is 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 is always best to check first, not after a loss. By the way, most automobile insurance companies 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; 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).
Wherever 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 before 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 is 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 if that ancillary goodie is really needed.
Some amateur just can't resist the temptation to install hardware they really don't need. A good example is a SWR/wattmeter for an FM radio. By the time the meter tells you anything, you'll no doubt already know something is a miss. The only case for installing one on an HF transceiver, is for manually tuning a screwdriver antenna. Even then, the one in the transceiver should be adequate. The same goes for some amplifier remote controls. A good example of that is the one sold by SGC. Since the SG500 amplifier can automatically select the correct band filter, a simple remote control switch is all that's needed. It pays to remember the KISS principle!
If there is one meter you should have on board, it's an accurate voltmeter (in dash units aren't very accurate). Remembering that a lead acid battery of any type (flooded or AGM) is considered discharged when the voltage drops below 10.5 under load, and that's happening while you're operating, you might have a wiring, or battery problem.
The voltmeter shown at left is a Martel Electronics QM-100V, two wire unit, and it is about the size you see here. Its current draw is a scant 2 mils, so it can be left in the circuit continuously. Martel also makes the QM120ET elapse time meter. I have one measuring the key-down time of my SG500 amplifier interface. Imagine nearly 800 accumulated hours in 4 years. Who could have predicted that much mobile operating time?
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, albeit a pathetic one. While you might chuckle, some installs I've seen aren't much cleaner, or safer! Some of those are in the Photo Gallery in the HOS (Hall of Shame) album.
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 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. Remember, the coax shield needs to be securely connected to the body of the vehicle (which acts as a ground plane). If the connection loosens (a regular occurrence when using clip mounts), common mode currents will flow over the outside of 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, as outlined in the common mode article.
Note the bent sheet metal in left photo. This type of repair is much more costly than that caused by a drilled hole. I suspect a lot more folks would drill holes to mount their antennas if they weren't so afraid of botching the job. As a result, some folks seek professional help from two way radio dealers and/or mobile sound shops to install their gear. Unfortunately, some of them don't know anymore than you do! If this is your tact, educate yourself with respect to proper wiring. And insist that you be allowed to watch the work being performed. If they say no, go elsewhere.
If you're having a radio or sound shop install your antennas as well, educate yourself about the various types of mounts. For example, the only VHF mount that is truly waterproof, even with the antenna removed, is a real NMO (New Motorola), and not some Pacific Rim knockoff! Incidentally, the various versions of the NMO produced by these Pacific Rim antenna companies, are not compatible with real, NMO mounts, so don't try to mix and match them.
While we're on the subject of mobile antenna mounts... Every single antenna mount, based on a UHF connector (PL259/SO239), will leak water to some degree. Remove the antenna, and they're virtually a sieve! Further, all clip mounts route the coax around the trunk's (or hatch, door, etc.) weather seal. If you live in a rainy area of the country, you'll discover their worth. They too leak like a sieve!
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 insult by using a clip mount, and RFI issues will abound.
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 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. Note the shredded piece of padded dashboard in the right hand photo. It was literally wrenched away by the force of the deploying air bag. Fortunately, no one was in the child seat during the minor rear end collision, which caused less than $300 damage to the front bumper facia.
You can get an even better picture by watching this video. This is why it is always best to mount radios (or their remote heads) below the center point of the dash fascia, and to the driver's side of center to avoid the passenger side air bag.
Speaking of mounts, the Radio Mounts article lists several manufacturers of pre-made mounts. Most all of them have models which use existing bolts (usually seat mounting bolts) to anchor them. Some of these utilize a stiff gooseneck arrangement, and based on my experience, not too satisfactory especially in off-road applications. The ones you don't want to use, are those which use spring pressure clamps. They won't hold a cellphone reliably, much less a 2 pound remote head replete with dangling wires!
When mounting the main chassis of your remotable transceiver, ovoid the underneath side of the package shelf (top trunk area), as that is the hottest part of the trunk area. Adding a fan blowing on the heatsink isn't much help either, unless it is fed with cool air from the vehicle's cabin (not very likely).
Another 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.
Transceivers should not be mounted directly to a surface, whatever it is. Rather, use the factory-supplied mounting bracket to hold the radio away from the mounting surface. This allows air to flow freely around the transceiver.
You might want to read the Wiring article, if you haven't already. 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.
When you do your wiring, don't bundle up unused lengths of wire harnesses. 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.
I once asked an amateur why he didn't shorten up the power cable between his auxiliary battery, and the main chassis of his radio six inches away. The reply was, that the power cable cost $15! This is a typical scrimper's response, and one which should be avoided; scrimping that is. By the way, PowerWerx carries all manner of OEM wiring connectors, Anderson Power Pole connectors, and wire for any installation, mobile or other wise. DX Engineering is another good source.
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.