A Mobile or Base Transceiver for Your Go-Kit

Training tip for 1-18-06

The first training tip, in early December, involved emergency power for your handheld, and we stressed the importance of having a power pack that accepts AA Alkaline cells plus a good supply of at least 3 dozen fresh AA alkaline cells on hand. Last time we discussed handheld accessories: having a better antenna than the stock rubber duck that came with the HT, having adapters to convert from your HT’s type of connector to PL-259, BNC or SMA, having a headset or earphones to hear better, to keep from contributing to the pandemonium present in the environment, to maintain privacy, and to preserve your batteries, and having a boom mike as a great convenience. We hope you made the effort to equip yourself with all of these things, or at the very least the batteries. When a disaster hits us, and it will sooner or later, you’ll be glad you made the effort.

Tonight’s training tip is about having a mobile or base rig as part of your go-kit. While it may be prohibitively expensive for you to justify having a spare mobile or base rig just sitting in the go-kit gathering dust waiting for an emergency, your plans for quick deployment to help out in an emergency situation should, if possible, include a mobile or base 2M rig if you own one, or better yet, a dual band or multi-band rig. Why? Your low-power HT may be unable to hit the repeater, or the repeater may be down for the duration of the emergency and unusable. The net may be on simplex frequencies and relaying from point to point. Having a low-power HT may not do the job, so you’ll need something as a back up with more power. A 2M mobile rig usually puts out 10-50 watts or more and with a decent antenna that is plenty to be heard well.

Unlike a handheld, a mobile or base station’s power requirements are considerable – AA cells won’t exactly do. The only way you can use a higher power device is if you have a higher power source. That means a big lead-acid battery or a 12V power supply using AC mains, if they’re available, or a generator. Let’s discuss each one.

A big lead-acid battery can be either the one in your car or a stand-alone deep-cycle marine battery. The car battery is a good choice, as it can be charged by running the engine from time to time. The rig can be permanently mounted in your car as a mobile radio and you can use a good quality quarter-wave or 5/8 wave antenna, either magnetically mounted, mounted on the trunk lip, or permanently mounted using a hole drilled in the vehicle. If you need to be operating mobile, this is the best way to go. If your assignment is to man a shelter or act as liaison at a fixed location, having a rig mounted in your car may not be convenient.

For portable operation like that, you can use a luggable lead-acid battery, but if you do that, get a deep-cycle marine battery. A car battery is made for cranking the engine to start it – lots of amps for a short time - and if you discharge it completely with long-term radio use, it won’t survive too many discharge cycles. A deep-cycle marine battery is designed to be discharged and recharged over and over. It will keep you on the air for a day or two, perhaps longer with conservative usage of the rig on medium or low power. It’s a heavy thing to carry, so be prepared to get help if you’re not in good physical shape. A charger is a good thing to have as part of your go-kit, too, so you can charge it from 120 volts AC, if you have access to it.

There’s a possible problem with running your brand new rig off a 12 volt battery, though. A lot of radios today have microprocessors that are designed to work at a nominal 13.8 volts, the charging voltage on your car battery, but they are not happy with any power source much less than 12 volts. A lead-acid battery is fully charged at 12.5 or 12.6 volts, and can go down to half charge at 10.5 or 11 volts, which is a safe level of discharge for the battery, but the problem is that some radios won’t work at that low a voltage. The way around this problem is with an inverter and power supply. The battery supplies power to the inverter as low as 10.5 to 11 volts, and the inverter supplies 120 volts AC to the power supply, which supplies 13.8 volts to the rig. The rig stays happy and operates longer this way than by working directly off the battery, even though the process is inherently less efficient. There is also the danger that the inverter may cause RF interference, but better quality inverters won’t do that.

If the AC mains are working at your emergency operation location, running a base rig off a 12V power supply is a good idea. Conserve the battery. Use a conventional or switching power supply. The new switching power supplies are lightweight and easily included in your go-kit.

If you have a gasoline-powered generator, use it with a power supply to keep the rig on. The main constraint may be source of fuel. Gasoline cannot be stored too many months without getting gummy, and you wouldn’t want to store more than 5 or 10 gallons anyway for safety reasons. The problem is that in an emergency, when there is no power, service stations cannot pump gas, so you can’t get any more. And modern cars make siphoning gas difficult or impossible. Propane and natural gas are alternative fuels that are gaining in popularity for just that reason. Home installations using these fuels are becoming more common, although they’re still pricey. But with automatic switchover when the power fails, you can live comfortably in your home as long as the fuel holds out. They’re not portable, though, and if you need to take a generator to a field site, a gasoline type is the way to go.

So much for emergency power sources. Now let’s turn our attention to antennas.

Antenna requirements for a mobile or base 2M rig are different from an HT also. That inefficient rubber duck won’t do at all. You need an antenna that will handle 25-75 watts, or whatever your rig puts out. Your best bet is either a simple j-pole like we discussed in the last training tip, or a mag mount quarter-wave whip antenna. For the mag mount to work well, it needs a good ground plane. In an emergency you can’t always count on having a large sheet metal object like a car or file cabinet handy, so it’s a good idea to carry your own. Have an old steel cookie sheet or pizza pan on which to mount the magnet mount. That can be put just about anywhere.

And what about the rig itself?

Simple 2M FM single band mobile or base radios are easy to come by and even brand new ones are very affordable these days. A good one will set you back 160-170 dollars or so and have all the memory capability you can use. I know this goes against the philosophy of some of you, but get out the manual and read through it – some features may not be intuitively obvious. In fact you may not even be aware they exist without reading the manual to find out! It’s a good idea to keep the manual or a photocopy of it in your go-kit. If you haven’t used the rig in a while, an emergency situation is no place to waste time trying to figure out how to access a repeater with a P/L tone. Another good reference book to have is the ARRL repeater directory, which is updated annually. It lists all the repeaters in your area, and you can program the frequencies into the memories of the rig. Modern rigs have alphanumeric labels that you can program for each memory channel. Learn how to do this. It really makes it easy to scan through the memory channels and see at a glance where the repeater is. It’s faster to read “Lancaster” than to see 147.03 and figure it out.

Dual band radios, if you can afford one, give you 2 meters and 70 centimeters in one box. Seventy centimeters, more commonly known as 440 MHz, or UHF (ultra-high frequency) is a lot like 2M in operation. There is some activity in Licking County on that band, and there are four repeaters listed in the repeater directory. In a serious emergency, they would no doubt be used, so if you have access to this band, use it to become familiar with it. If you are in the market for a new rig, take a look at a dual bander. They are more affordable than ever and come packed with lots of useful features.

Multi-band, multi-mode rigs, like the Icom IC-706 or Yaesu FT-857, for example, incorporate the HF bands, VHF bands (6 and 2 meters) and UHF band (70 centimeters) all in one compact box. There isn’t much real estate on the front panel, so most of the radio’s functions are accessed by means of menus and submenus with function keys. This takes some getting used to, and is not something you want to get familiar with during a disaster, so if you have a radio like this, or are contemplating getting one, be sure to practice a lot with it so you are very familiar with its operation and are comfortable using it. Recognize that the one disadvantage of a multi-band rig is that only one band can be used at a time. If you are in a situation where both HF and VHF/UHF capabilities are needed simultaneously, presumably with two or more operators, you would be better off to have separate rigs for HF and for VHF/UHF.

HF only radios can also have their use in an emergency, too, mainly to pass traffic into and out of traffic nets, such as the Ohio ARES net on 75 meters or the hurricane watch net on 20 meters. These radios, and the multi-mode, multi-band radios just described will need suitable antennas for the bands you plan to operate. At the very least, antennas for 75, 40, and 20 meters will be good to have. Dipoles are balanced antennas and don’t require a good ground, something that might be inconvenient to establish in a temporary emergency set-up. One good antenna is to mount mobile vertical antennas base-to-base to make a horizontal dipole. This antenna setup can be mounted on a mast 10 or 15 feet high and will do a creditable job getting a signal out. And speaking of signals, most of the time for regional HF nets, you don’t want an antenna with a low take-off angle or your signal will skip over your target. You’re not hunting DX so you want your signal to go up high and bounce back to the receiving station located a few tens to a couple hundred miles away. A low antenna like I described will do this, and its technical name is near vertical incidence skywave, or NVIS for short. Feed it with 100 watts and you’ll probably be heard well enough.

A lot more can be said about mobile and base equipment set up for emergency operation, but we’ve covered the fundamentals here and, we hope, given you some food for thought. Here is your homework assignment to accomplish before the next ARES net on February 1.

1. If you have a base or mobile rig, for 2M only, or dual band, or multi-band, first go find the manual for it, and read through it, especially with regard to adjusting output power, switching between VFO and memory channels, and storing repeater frequencies and P/L tones into memory.

2. Make a copy of the manual for your go-kit.

3. Then get hold of a recent copy of a repeater directory, or see the web page on the new Licking County ARES web site labeled Repeaters, and make a copy of this information for your go-kit. And while you’re at it, print out the other pages on the web site too. It’s good to have it all in your go kit
4. Finally, program as many of these frequencies, plus the P/L tones if used, into memory and label them with alphanumeric labels if your radio has that feature. Make sure you can bring up the repeater, identify yourself, and get a signal report if possible, to find out how well you’re getting into it. It’s better to check out your equipment and know how to use it BEFORE the emergency than during it!

ADDENDUM:

"John W8NM commented that in the discussion on batteries, gel cells should be included as a viable power source. They provide a good ratio of amp-hours for the weight and are fairly inexpensive. Eldon W8UHQ commented that they provide a safety factor as well, since there is no hydrogen outgassing as with conventional lead-acid batteries. Bob K8LJ added that his experience has been that they don't last as long as a good marine battery. Steve N8WL had considered that gel cells were a subset of lead acid batteries and had no intention of omitting discussion of gel cells, and in fact he owns and uses one, too. They are indeed a viable source of emergency power and should have been included in the foregoing training tip."