Last Modified: November 21, 2011
Contents: Basics; Personal Selections; The Antennas; Cap Hats; The Radios; The Amplifiers; The Controller Boxes; Active Audio Filter; Video Display; Where To Find Me; Odds & Ends;
I often get ask what I use mobile, and why I use it. The answer is easy, yet difficult, without some further data. What follows is one of the many different mobile configurations I have used over the 40+ years I've operated mobile. Some of my decisions are based on experience, some on current technology, and some because it is much safer to use. Let me give you a few examples.
I have seen mobile installations that are beyond belief. While the one in the right photo might have been staged, it isn't too far removed from some I've seen in person. If this vehicle were to be involved in a crash, and the passenger side air bag (SRS) went off (exploded), just about every item you see installed on the dash would be sent flying at about 200 mph! I've even seen remote transceiver heads mounted in the center of the steering wheel, directly on top of the SRS!
As bad as these scenarios sound and look, by far the most deadly are those caused by distraction. Distraction, primarily from cellphone use (primarily texting), has surpassed drunk driving as the major cause of vehicular deaths. It should be obvious, that any device we install and use, should be used to reduce distraction, not increase it.
It should also be installed in such as fashion as to be easy to reach, clear of all vehicle controls, and out of harms way ( away from the SRS devices). What's more, just because you've seen what appears to be a safe mobile installation in some amateur radio article (net or print), it could be just the opposite.
As you can see from the left photo, passenger side airbags are much bigger than most folks realize, especially those in large SUVs. Large enough in fact, to virtually rule out any dash mounted device.
There are good reasons why I have selected what I have. For the most part, it is because I have actually used, and rejected, most of the other currently-available gear. This includes antennas, transceivers, amplifiers, and antenna controllers. That in itself doesn't mean the other gear wasn't worth the price of admission, albeit sometimes that was the case. Call it personal preference if you wish. However, some of the available gear I wouldn't own on a bet, whether I have personally tested them or not. A good example are the various short, and stubby antennas which have become the current rage. They are not the stuff of champions!
I've lived with, and learned from some of my purchases, a few of which were rather costly in terms of money, and time! One good example comes to mind, but a mere mention of it might sound as an endorsement, so I will not mention it. I will say this, however. The attitude of the people you deal with when asking questions prior to purchase, are always a good indication of what is to come after the purchase. Caveat Emptor!
I've also learned that on-line reviews don't mean much for a variety of reasons. For example, the Yaesu ATAS series consistently rates 4 out of 5 stars, yet it is the lossiest, most trouble-prone, remotely tuned, HF mobile antenna money can buy. They're prone to common mode problems, and if you live in a very cold, or very hot part of the country, you'll find they don't work in either extreme. In spite of all of this, until recently, it was the number one selling, remotely-tuned, HF mobile antenna. Go figure!
Further, the price you pay is not always an indicator of quality, workmanship, longevity, or even as an implied warranty. It doesn't correlate to efficiency, or ease of use either. Whatever selection you make, the best advise I can offer is this. If at all possible, try it, before you buy it!
I have no idea how many different mobile antennas I have used over the years, but I remember the first one. It was a 15 meter HyGain coil and mast, with an extended whip which allowed it to operate on 20 meters. I was using a Heath HW32 at the time (20 meter monobander), so 20 meter operation was enough. After I built a home brew amplifier in 1973, it because necessary to replace it with a Master Mobile coil, as the HyGain wouldn't handle 400 watts PEP output from the amplifier.
I've used about 20 different commercial HF antennas, and a lot of home brew ones too. I currently use a Scorpion 680. Field tests proved it is ≈4 dB better on 80 and 40, and ≈6 dB better on 20 and up, than my previous antenna. It is, in fact, the best made screwdriver antenna I have ever seen, or used!
The 6 meter antenna is an M-Squared HO Loop. It isn't mounted as high as I would like (I garage my Ridgeline), but it does work well all considering. In the not too far distant future, I plan on mounting it on a special fold over to increase its height to about 13 feet.
The very first VHF antenna I ever bought (1971) was a Larsen NMO150. I still own it, and it is still in near daily use. It has been installed on at least 20 vehicles, and atop about a dozen NMO mounts (I usually leave them in place when I trade). The current VHF is a Larsen NMO2/70BK dual bander. It is mounted on its fifth vehicle. I've crunched it twice with the garage door, and it is still working perfectly. You can't say that about any import.
There are two additional antenna mounts (right front, left rear) not seen in the photo. They're used for testing purposes. After all, you can't write about something unless you've tried it!
There are more photo of my installation here.
Since early Spring, 2008, I have been playing with a variety cap hat designs, with the help of Ken Muggli, KØHL. If you read the article, you'll know why we've spent the time exploring the various possibilities. They do increase the radiation resistance (Rr), and they can reduce the overall length. Quite often, they do both. The fact they increase the Rr by raising the antenna's current node, is evidenced by the ≈3 dB increase over the field test figures (original model) over the same antenna using just a 102 inch whip. The new cap hat design offers even better performance, especially on 80 meters. Even more significant, is a reduction in weight of the three loops combined, of just over 9 ounces.
The cap hat is mounted atop a 5/8 inch, by 48 inch, 6160T6 aluminum mast. The three loops are made from .125 by 72 inch long, 6061T6 aluminum rod. The effective outer diameter is ≈58 inches. Mounted atop the mast—the correct position for any cap hat—its equivalent electrical length is ≈120 inches depending on the frequency of operation. The tip of the cap hat remains below 13 feet, even on 80 meters.
It is interesting to note, that the previous cap hat (.200 by 60 inch, 17-7 stainless steel whip, with three loops are .125 by 60 inch, 17-7 stainless steel wire, and an effective outer diameter is about ≈40 inches) was nearly 2 dB down on 20 meters from the current one. This is partly due to the conductor losses in the stainless steel wire used to make up the cap hat.
I've probably missed one or two, but I'll try to name them all. For 2 meters, a converted Standard 12 channel business radio, and an Icom IC-25H (in daily use since 1977). That's 32+ years of service, and I've never had to replace or repair any part of it.
As I said above, my first HF radio was a Heathkit HW32, 20 meter monobander. I bought it used, and the only thing I ever replaced was the driver and the two finals. I used it for about 3 years. I've also owned (and operated mobile with) a National NCX3, and an NCX5. From Atlas Radio a 180, 180X, 215, 215X, and a 210X. From Icom a IC701, IC730, IC735, IC751, two IC706MkIIgs, and two IC7000s (one the current mobile shown below right).
The biggest advantage latter-day transceivers have, is their built-in DSP. Some might argue that their noise blankers are better, but I'm not sure. The one in my last Atlas (210X) was as good as any I have used, and one of the few that effectively removed the Russian woodpecker (you do remember the woodpecker?).
Missing from the list are Yaesu and Kenwood transceivers. I've had two Yaesus, a FT100 and FT857D (both bought used), and one Kenwood, a TS480Hx (bought new). I sort of operated them mobile as a cross comparison, but not permanently installed. The FT100 was difficult to use because of the small display. The FT857D was marginally better, with the exception of the menuing. I don't think any manufacturer has got menuing down pat, including Icom!
The Kenwood TS480Hx is about as good as Kenwoods get. Subjectively, setting side by side with a (borrowed) TS2000, I can't tell the difference. I think the DSP is better in the 480, and the noise blanker is slightly better in the 2000. The real advantage for the 480Hx is its 200 watts PEP output. Call it a poor man's amplifier, for just slightly more cost than the base TS480Sx. If you have the room for the large remote head, it is a decent HF mobile with a lot of punch.
I have some additional information of the current mobile offerings here.
If you're a casual mobile operator, I don't think an amplifier is a wise purchase. They require the best of wiring and installation practices, and a very good quality antenna. Based on the number of installations I've seen, the vast majority of operators would gain more by remounting and/or relocating their current antenna, and for quite a few, replacing their antenna altogether. I have a lot more information about this in my Antenna and Mounting articles.
To date, I have used two home brew amps, and four commercial ones. My first was home brewed (straight from the ARRL handbook). It used a P&H LA400 mobile power supply, and utilized four 6KD6 sweep tubes. Since I only operated 20 meters at the time, it was a monobander. I did build a multi-band mobile amp using four 4CX250Bs, but to be honest, it didn't work out too well.
My current amp is the SGC SG500. It has much better fault protection than any currently available mobile amp. It has RF keying, which I don't use because of the extra keydown delay (≈100ms). The fact the key up delay isn't adjustable adds insult.
Probably its best feature is automatic band selection. I've tried every scheme you can think of to automate band selection. No matter how you do it, no matter how careful you are, sooner or later you'll transmit into the wrong bandpass filter with predictable results. Use the automatic feature, and that just can't happen. The only drawback is a slight delay (≈250 ms) on first keydown , and about 100 ms thereafter. By the way, the SG500 is the only (legacy) mobile amplifier which can be keyed directly (no interface) by most Icom , and Yaesu transceivers.
As bullet proof as it is, if you use one of these amps, and it is mounted in the trunk, do yourself a favor and buy the extra cost fan kit. With an adequate power feed (and the fan kit), the amp will keydown forever at 500 watts out! This sort of capability doesn't come cheap, but quality never does. I own two of them, and one has 1,000 hours of mobile keydown time (SSB) without a hitch!
Running more than 500 watts out can be done. I know several people who use an ALS-1300 mobile, powered by a variety of subsystems. The aforementioned 4CX250 home brew amp would easily run full legal limit. But once you get past 500 PEP, things start to get rather difficult. One limiting factor is the antenna. Contrary to published specs, precious few HF mobile antennas will actually handle 1,500 watts PEP, much less a dead carrier, unless they're poorly mounted (having a dominance of ground losses). But that is not the only limiting factor. All on-board electronics are vigorously tested to assure their survival in high RF energy fields. However, when the wiring between the various on-board devices is exposed to high levels of RF, the signal paths can be disrupted causing all manner of glitches. Some of these glitches (ABS controls for example) can be dangerous to your health in ways RF never could on its own!
The little black box in the right photo is a Better RF Tune control unit, which plugs into the tuner and CI-V ports of the IC-7000. When the Tune button is pressed, the radio switches to RTTY mode, and transmits at about 30 watts. Push the button again, and the radio reverts to its previous mode. This is one of the few tune modules fully compatible with the IC-7000.
The BetterRF Tune Control plugs into their 7000 Screwdriver control via a 2.5 mm stereo cable (all cables are included). The controller has some very unique features.
First, all of the setup is done using existing controls on the Icom IC-7000 it was designed for. Setup takes all of 5 minutes, as the run and stall currents are automatically detected. It plugs into their 7000 Tune Control. All that's necessary is to provide a 3 amp fused circuit to power the antenna's motor. The only modification required, is changing a jumper (or switches) located inside the tuner unit.
The SWR default is set 1.5:1 , which may be changed up or down as required. You can manually operate the antenna if needed, but you won't need to as this unit works perfectly, every time! There's even an amplifier bypass relay (both NO and NC).
Once set up, when you QSY you simply push the Tune/Call button, and the controller takes over, always moving the antenna in the correct direction. If the motor overshoots the programmed SWR (dynamic braking minimizes the possibility), the controller detects this. It then reverses the direction of travel, switches to PCM (pulse-code modulation), which runs the motor at half speed.
I have tried 6 different commercial controllers, including both manual and automatic, SWR and turn counting, and this has been the best one.
The black box in the right photo is a Hammond cast aluminum one (available from Mouser and DigiKey). The rectangular object is a Martel two wire voltmeter. The switches control the amplifier, video to the Navi (see Video Display below), and remote coaxial relay (not shown in the photos) which switches over to the 6 meter loop when needed. All of the cabling is straight forward, and has Molex connectors on both ends to ease installation and removal.
Speaking of black boxes. I typically don't leave things alone, as I'm always looking to make things easier, less distracting, and above all, reliable and easy to work on. In that vain, I remounted my BetterRF TCSC inside a large Hammond cast aluminum box, along with some extra goodies, and bolted the assembly to the top of the amplifier using existing screws.
All of the various control, and power cabling connects through the box. This includes the amplifier's control wiring, the cable from the remote switch up front, the CI-V and accessory socket cables (PTT & ALC), and the power out to the antenna. The meter is an hour meter, which measure the up-time for the amplifier. There are three LEDs. One indicating power to the box, a bicolor indicating power out to the antenna, and an ALC indicator. These are used for trouble shooting, should the need arise.
Out of view is an 18 volt, 50 watt Zener to clamp any transients, and several bypass capacitors for the incoming power. These are used to protect the meters (voltage & hour).
The power to the amplifier, and second battery are fed to the amplifier through 120 amp Anderson PowerPole connectors (one is barely in view to the lower left). Since the IC-7000's main chassis is bolted to the amplifier's fan assembly (it is behind, and below the black box), and all of the wiring is connectorized, the whole assembly can be removed in a matter of minutes when required.
I've used passive filters for many years, to cut back on the high-frequency hash we all have to deal with. They do work well, and don't require any power. However, they do rob a little power in that they do have insertion loss. Depending on the design, that can be as much as 4 or 5 dB. Some transceivers meant for mobile use, lack sufficient audio power in the first place, and a passive filter just adds insult.
A good example is Icom's IC-7000. It is audio amplifier is rated at 2 watts RMS, but it has a hard time doing 1.5 watts, and if you remotely mount the head, the loss in the interconnect cable takes an additional toll. There is a solution,and it comes from Idiom Press.
The SCAF-1 is an adjustable, lowpass, active filter with 96 dB per octave rolloff, which is very impressive. The cutoff frequency is adjustable from 3.5 kHz, down to 450 Hz. It is half watt output may be too low from some applications, but it has proven to be enough in my personal installation. It sells in kit form for about $100 including shipping. Assembly time is 4 to 8 hours depending on your skill level.
The SCAF-1 isn't a cure-all for the mobile noise level we all have to endure. However, there are times when the SCAF allows a contact to be made, that couldn't be made without it. While DSP units, especially IF based ones, do a very creditable job in reducing atmospheric noise levels, the extremely steep skirts of the SCAF adds a level of reduction, effective at least 50% of the time. Your mileage may very, but personally... I'm sold on it!
By the way, if you don't operate CW, you can order a SCAF in kit form set up just for SSB. It is a little easier to fine tune perhaps, but is otherwise identical in performance.
TVandNav2Go makes a video interface for almost every factory-installed navigation system ever made. It is housed in a small metal box, about 1 x 3 x 4 inches, and sells for $250. Most of the competition is at least $100 more. The instructions are rather lame, however it is easy to install. If you have an Icom IC-7000, this is a great addition worth the price of admission, if for no other reason than to reduce distraction.
By the way, the unit has an additional video input (Video 2), commonly used for a backup camera. It too can be switched, and it also takes precedence over the Video 1 input. Using it for a DVD player is contrary to most local laws, so if you do, you're on your own.
I often get asked where and when I operate mobile. Unfortunately, there isn't a pat answer to that. Being retired (mostly), I turn on the Icom IC-7000 anytime I'm in my vehicle. Like most mobile operators, I do more listening than talking, and as a result I don't call CQ very often, even though that's fairly easy for me to do using a modified BetterRF iMate.
Remember, I've been at this for 38 plus years, so the country list is over 300, and I have 302 cards on-file with the suffix /m or words to the effect. If I find one I haven't worked, I may very well jump in based on the signal strength of the desired station.
To directly answer the question, when 20 meters is open, I'm listening on 14.255 MHz at 8:00 and 17:00 Mountain time almost every day. When 17 is open, I hang out between 18.140 MHz, and 18.144 MHz when I'm in the vehicle. I also do some 6 meter work here in grid DM73, using an M-Squared squalo.
In any case, look around and sooner or later you'll hear me (if the bands will cooperate!).
All of us are on a learning curve, and it is a poor day when we don't learn something useful. One of the first lessons I learned after becoming an amateur radio operator, was the absolute importance of having a good antenna. This is especially true for mobile operation. The HyGain 15 meter antenna I spoke about above, is a very good example.
It came with rather large brass end caps, which held an outer fiberglass cover in place. I broke that outer cover by hitting a low-hanging limb. I simply removed the end caps and cover entirely. Suddenly, my near perfect (so I thought) antenna would no longer work properly. This started me on a quest to find out why this was so. It was, and still is, the impetus behind my fascination with mobile operation in general, and mobile antennas specifically. For more information, read the Antenna Efficiency article.
By the way, the reason the antenna didn't work correctly is simply this. The end caps not only reduced the Q of the coil, they also change its inductance. This required a change in the length of the whip, to bring the antenna back into resonance.