Friday, May 18, 2007

The Right Tools

by Ron Hashiro, AH6RH
Scotty, the engineer on the original Star Trek series, was always fond of saying "How many times do I have to tell you...use the right tool for the right job!" As an amateur radio operator involved in emergency communications, do you know what are some of the right tools of the trade? Let's take a look.
Mobile Radios While we like the convenience of a 3 or 5 watt walkie, nothing beats the transmitting distance and the receiver qualities of a 50 watt VHF mobile or a solid HF transceiver. A rubber ducky and a handie talkie really won't cut it for most emergencies that rely on direct simplex communications on level terrain over distances greater than about two to three miles. And a mobile radio has better intermod rejection than a handie. Living and working in Honolulu, we know what a miserable, frustrating time we get from intermod signals.
Antennas If you're insisting on using a rubber duck antenna, you're in big trouble. A rubber duck is really a rubber coated dummy load. To get better performance, you'll need something you can attach to a coax cable and get the antenna closer to a window (if you're inside a sealed air conditioned building) or outdoors to radiate your signal better while you're safe and comfortable inside.
For walkies, a collapsible quarter wave or half-wave "hot-rod" antenna is a start. You can also use a ribbon j-pole antenna. But for mobile radios, you need something that will dissipate 50 watts continuous and many of the commercial walkie antennas are designed for about 5 watts. A regular quarter wave ground plane, mobile magnetic mount antennas -- these are good, portable antennas that are small enough to be used to radiate through a window in a office building or school cafeteria being used as an evacuation shelter.
If you are using a fixed based station, do not be so quick in getting the highest gain vertical antenna you find. Gain is obtained by sacrificing the antenna's radiation pattern. Rather than choosing a 7 dB vertical that slams your signal 100 feet into the building next door, selecting a 3 dB vertical gives an omni-directional antenna with a boost in gain but still allows sufficient radiation from the side lobes to rise over mountains, condo buildings or bend around other obstructions.
A handy item is a portable three or four element beam. A 6 dB gain is worth a four times increase in transmitter power. More importantly, the four times increase in received signal is very handy for pulling out marginal signals. As an example, check out the 146-4 Back Pack from Arrow Antennas (
Coaxial Cables Let's face it. Without feedline, it's mighty hard to get a signal from your radio to the antenna. You would like to position the antenna near a window if you're high above the surroundings, or at least higher than the surrounding obstructions to get the signal out.
If you had a chance, hauling 50 or 100 feet of RG-8U would be an ideal medium loss HF, VHF and UHF feedline cable, but it's mighty bulky and heavy. Using RG-58U is smaller and lighter, but the losses at VHF and UHF starts to cut into your operations.
A compromise is RG-8X, which has the bulk of RG-58U but has loss characteristics close to that of RG-8U. The only "drawback" is that the reducers used with PL-259 coax connectors are the UG-176 variety (for 75 ohm RG-59U) rather than the standard 50 ohm UG-175 for RG-58U but that's a small inconvenience.
Headphones and Other Accessories Little things make a big difference. Using headphones and a boom mike will cut out the background noise in a busy, cluttered environment and will also keep your audio from blasting around an already noisy room.
To speed operations, you may want to also include a foot switch to key your radio with your foot to leave your hands free for writing messages and adjust the radio.
Something as simple as a clipboard ensures you'll have a smooth hard surface to write down messages clearly and legibly no matter where you are.
So, there you have it. A quick run through some simple things that make a big difference in responding to emergencies. Now, it's your turn to be like Scotty and say: "Use the right tool for the right job!"

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