"Getting the Most from Your Hand-Held Transceiver"

Copyright 1998, 1999 VARI

When limited to "barefoot" operation, with a "rubber duck" on simplex, HTs are not adequate as a primary rig for emergency communications.

I started with an HT when I first got my license. Today, I would recommend a mobile as a first rig, and if need be, carry it in a briefcase with a suitable gel cell battery for portable use, with the caveat that it doesn't work for everyone. If all you have is an HT, the following is recommended to enable you to "make the most of it."

An HT does make perfectly good sense for:

  1. Anyone who doesn't drive;
  2. Commuters who use public transportation;
  3. Controlling dual-band mobile in cross-band repeat or;
  4. As a "spare," backup or loaner.


FACTS ABOUT HT ANTENNAS

National Bureau of Standards tests of Public Safety high band and amateur 2-meter antennas indicate that a "rubber duck" has -5db, "negative gain" compared to a quarter wave held at face level. In terms of effective radiated power (ERP), this means that a 5w HT with rubber duck, radiates only 1 watt. Placing an HT on your belt results in another -20db attenuation, reducing ERP to 50 milliwatts! UHF results are no better...

This simple helical spring is intended to withstand rough handling, but is not indestructible. Flexible antennas used on fire lines for several weeks showed a 60% failure rate. The California Auxiliary Communication Service recommends that flexible antennas be replaced annually or as soon as they show apparent kinks, abrasion or other wear to visual inspection.

A simple, inexpensive and effective expedient to improve a "rubber duck" is a counterpoise or "tiger tail. Make this from a quarter-wave piece (19.5" on 2m, 11.5" for 220 and 6.5" for 440) of stranded wire, crimped and soldered to a battery clip. Always reinforce the soldered connection with heat shrink tubing or tape to resist flex. When clamped to the outer collar of the BNC connector on your HT antenna, the counterpoise prevents RF from coupling with your body, so your antenna acts like a center-fed dipole instead of an end- fed dummy load! In marginal conditions extend it horizontally, pointing your hand to direct the main lobe of the radiation pattern in the direction where you need a stronger signal.

Several HT antennas are commonly available which perform much better than the standard helical "rubber duck." A J-pole antenna constructed of 300-ohm twin-lead rolls up and fits into your pocket. When thrown up in a tree, it increases antenna height and gain. Flexible 1/4 wave and telescoping -wave antennas also work well.

A quarter wave provides unity gain when used with a "tiger tail" or counterpoise and held at face level. This represents a 5 db improvement over a typical rubber duck, because more of the effective signal is radiated. If using an HT in a vehicle, use a mobile mag-mount antenna to provide a clear RF path outside the vehicle. This overcomes the -20db attenuation which otherwise results from operating your HT with a rubber duck antenna inside a metal vehicle. Always carry a male BNC to female UHF adapter so that you can attach your HT to an outside base or mobile antenna, when one is available.

In marginal operating locations a telescoping half-wave is a better performer, because it provides the same unity gain without a ground plane that a 1/4 wave does when used with a ground plane. A -wave antenna can be pulled up into a tree, dangled out of a window, attached to a window pane with suction cups, or be used bicycle or motorcycle mobile, or in city driving on a window clip mount.

Adding a ground plane or counterpoise to a -wave produces about 2 db gain. A telescoping half-wave boosts the readable simplex range of a typical 5 watt, 2-meter HT from about a mile with a rubber duck to 3 miles or more, depending upon terrain. Adding a tiger tail to a full-sized quarter-wave or telescoping half-wave dramatically improves receive and in favorable terrain extends simplex range of a typical 5-watt handheld to about 5 miles under average HT-to-base suburban conditions.

Telescoping antennas are more fragile and work best when stationary or in the open, avoiding side impacts or rough handling. Avoid prolonged mobile use of telescoping antennas on mobile window clips at highway speed, because excessive flexing loosens the internal electrical connections. Never collapse a telescoping antenna by whacking it down with the palm of your hand. Gently pull it down with your fingers. If you note any wobbling or looseness, replace the antenna.

Flexible antennas are safer when working in close quarters around people and are more durable when walking through dense vegetation for wildfire suppression or search and rescue operations. They better for dual-band transceivers because telescoping antennas are usually single-band. Most dual-band flexibles approximate a 1/4 wave on 2 meters and a 5/8 wave on 70 cm, are optimized for one band and may resonate poorly on the other. Some do perform better than others. How efficient a particular antenna is can be determined for sure only by testing.

If you want to buy an emergency HT gain antenna, a telescoping half-wave, long-flexible, dual-band quarter wave; or a half-wave, dual-band-mobile magnetic mount, which works without a ground plane, offer the best "bang for the buck." Any emergency HT gain antenna you get should be able to handle at least 25W so that it can also serve as a mobile antenna or be used with a brick amp.

In our experience the Comet CH-72 and SBB-1 dual-band flexibles, rated for 50w, and the Larsen telescoping half-wave, rated at 25w work very well. Adapters enable any of these to be used on an HT, attached to a mag mount or pulled up into a tree with its attached tiger tail and coax to a mobile rig or brick amp.

A mag-mount works best on a car, but an improvised ground plane can almost always be found around the home or office, such as a metal filing cabinet, metal trash can, cookie sheet, rain gutter, refrigerator, window air conditioning unit, balcony railing or any other large metal object. On bikes, boats, motorcycles, fiberglass truck caps or wooden balcony railings use a half-wave which doesn't require a ground plane.


BATTERY POWER BASICS

A common error of new operators is failure to carry enough batteries to last through an event. Hand-held transceivers for ARES should have either an external power socket or an extra AA battery case which enables you to keep operating if you can't recharge your NiCads. That fancy new HT with lithium-ion battery is useless when the power goes off unless it can optionally powered by the Energizer Bunny or from an external battery!

Cycle and recharge dry nicad packs at least monthly. Write the recharge date on a strip of tape on each pack. In cold weather keep NiCd packs warm by keeping them in an inside coat pocket and not exposed on your belt.

Adapter cords enabling you to take power from an auto cigarette lighter plug or a gel cell battery are usually needed for extended operation. Cigarette lighter plug cords are often unreliable because the sockets are often contaminated and not the best conductors. They also vary in size so that the plug may vibrate loose. As an alternate power source you should still have one, because they are ubiquitous and in a pitch it is much better than nothing!


STANDARD POWER CORD CONNECTORS

Auxiliary power cords to power your HT and small brick amp should follow the wiring configuration shown in the ARRL ARES Resource Manual. Use twin lead AWG12 to AWG16 gauge "Zipline" with Molex Series 1545, 2-pin polarized connectors and .093 pins. In ARES practice the female pins are assembled into the male plug which is attached to the power source, and the male pins into the female receptacle which is attached to the rig. The plug receptacle and pin set is $0.99 from Radio Shack, Part No. 274-222. These are rated at 8 amps, which is adequate to power small brick amps up to 35w output. Tech America carries the genuine Molex parts in bulk, which are rated at 11 amps and suitable for brick amps or mobiles up to 50w.

Wiring is simple. The end of the two-conductor Molex plug in cross section resembles a little 2-story house with peaked roof. Remember proper polarity by the word associations "red roof" and "black basement," or "pointy positive" and "flat black." Crimp wires before soldering to ensure a strong connection. After inserting the pins into the plug and receptacle, check fit of the assembled fitting and reinforce the wires behind the plug and receptacle with heat shrink or tape. On the battery ends attach crimp type .187" female tab terminals to fit the male tabs on the battery. Wire a plug receptacle onto the leads of a 12-14V, 250mah-500mah wall transformer and for normal charging use a time and current to equal 120% of the battery's capacity.

It is recommended that you rig two sets of cords directly to your car battery to power an HT and your brick amplifier instead of using the cigarette lighter plug. Splice type fuse holders onto both leads, as close to the battery as possible. Use 2 amp fuses for the HT and 10 amp fuses for brick amps up to 40w. Use different wire gages such as AWG16 for the HT and AWG12 for the brick amp, so that the two different cords are readily distinguishable by sight and feel.

If all you have is an HT, the above will enable you to make the most of it so that nobody will complain about your "worthless and weak, hand held baby monitor!"

Nonprofit reproduction permitted with attribution, C. Edward Harris, KE4SKY, State Training Officer, VA RACES

Page Last Updated, 03/05/04

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