Glendora Emergency Response Communications

EMERGENCY OPERATIONS & YOUR HT, Part Two

May 29, 2010

Good information on Batteries.  N7YLA

Jun 22, 2004

March 30, 2004

Bulletin Courtesy Santa Clara County, California ARES/RACES

Before I begin, I would like to give credit to C. Edward Harris, KE4SKY, AEC for Fairfax County ARES in Virginia for his article on "Getting the most from your Hand Held Transceiver." Much of this script has been taken from that article. Some minor editorial changes have been made to make it more readable over the air.

BATTERY BASICS

For Emergency Operations, it is highly recommended that you carry two fully charged Nicad packs and an extra AA battery case and batteries. The Nicads will power your HT for at least the first full day of operations and the AA's will allow you to continue to operate if you can’t recharge your Nicads. It’s also important in cold weather to keep Nicads warm, and not exposed on your belt.

As an alternate or primary power source, use 12-volt, 2 Amp hour or higher Sealed Lead-Acid or Gel Cell batteries. They fit in a coat pocket, run an HT all day or power a 2 meter mini-amp for 3 hours at a typical duty cycle. Sealed Lead-Acid or Gel Cell batteries have many advantages. They will allow you to:

1. Operate when other forms of power are not available

2. Operate longer than with NiCad or Alkaline batteries; 1–3 Ahr batteries are still small enough to be hand carried.

3. Operate mobile, portable or fixed at a higher output power

4. Operate at a lower cost; Gel Cells and SLA’s (sulfur lead-acid) are less expensive than NiCads or alkalines.

5. Operate with fully charged batteries at all times; It’s possible to keep these batteries on a "smart" charger continuously.

Sealed Lead-Acid batteries are used to power medical diagnostic instruments, alarm systems and Un-interruptible Power Supplies (UPA) just to name a few. Depending on the criticality of the application, some organizations replace their batteries on a regularly scheduled basis well before they are worn out and require disposal as hazardous waste. You can generally find them at the ham swapmeets.

If you decide to use Sealed Lead-Acid or Gel Cell batteries, you'll need a battery charger. 12 V Battery Chargers are available from various sources:

You can also use so-called "Wall Warts", but the general consensus is that your batteries won't last as long on these inexpensive chargers.

Of course, you can always build you own. Two very good articles are the:

June ‘87 issue of QST entitled "A New Chip for Charging Gelled-Electrolyte Batteries"

This article uses the Unitrode UC3906 "Smart Chip".

March ‘94 issue of QST entitled "A Lead-Acid Battery Charger"

There is also some very good information available on the internet. I have several good URL's that I can pass along if anyone is interested.

http://www.unitrode.com Unitrode – Home of the UC3906 "Smart Chip"
http://www.benchmarq.com/ Benchmarq chargers
http://www.ibexmfg.com/ Ibex battery chargers
http://www.yuasabatteries.com/ Yuasa "Battery Handbook and Technical Guide"
http://www.electriciti.com/batteri/pwrson1v.html Powersonic batteries

AUXILIARY CONNECTIONS

Power cords for connecting to automobile cigarette lighter plugs or gel cell batteries will be needed for extended operation. Be aware that cigarette lighter plug power may be unreliable due to contaminated cigarette lighter sockets. Also, the sockets themselves vary in size, allowing the plug to vibrate loose. As an alternate source of power, however, everyone should still have the capability since they are readily available. We will cover the pros and cons of the preferred Anderson Power Pole and Molex connectors in detail in an upcoming training meeting..

HAND HELD DUTY CYCLE LIMITS

If you subject your compact HTs to frequent full power 5w transmissions of several minutes duration they will overheat and the final power transistors may fail prematurely. For example, Kenwood and Yaesu state in their service manuals that their HTs are rated for 20% duty cycle at maximum RF output, or 30 seconds of transmit to 2 minutes of standby. Be sure to know the duty cycle capability of your radio equipment.

You have noticed by now that I unkey frequently to avoid such a disaster even though I am using a mobile rig. The radios we use at the Main Facility have very large heat sinks to allow for extended transmission time, but we use the minimum power necessary to conduct the net.

It is best to use your HT mostly on medium or low power for long winded rag chews and restrict full power 5w use to short transmissions to save the finals. If you have a need for high power transmissions of several minutes duration and can’t replace or supplement your hand held with a mobile rig, I would advise getting a power amplifier to do the heavy work. Just remember to reduce your HT's output power going into the amplifier, otherwise, you will still burn up your finals.

ADVICE ON POWER AMPLIFIERS

An excellent way for HT owners to upgrade their portable equipment is to purchase a power amp. An ideal amp should weigh less than 1 pound, be capable of 10 to 15w output when driven by an HT at 1w, or 20 to 40w output when driven by the same HT at 2 to 3w output. It should draw no more than 8 amps of current at its maximum rated output, enabling it to operate safely from a 15 amp Anderson Power Pole connector or the .093 diameter pin Molex Series 1545 connector or fused cigarette lighter plug.

An FM-only amplifier without a preamp will be adequate in most cases. A preamp tends to accentuate intermod due to paging transmitters. Unless you equip your portable station with a notch filter and/or cavity bandpass to suppress this intermod, the preamp will serve no useful purpose. Be wary of bargain "no-name" amps you see at hamfests or in discount catalogs. Some are not aligned for the entire U.S. 2-meter band, many lack thermal protection circuitry for over -voltage, or simply have an inadequate heat sink and will overheat and quit.

73 DE KF6DSA