Power: Input And Output
Transmitter output power is crucial to successful communication because,
along with antenna choice, it affects communications range. Check with
local hams about the power levels required to "hit" (access) popular
repeaters and for effective simplex contacts. The local terrain should
be considered; flat, open areas require less power. A handheld radio
should be capable of 3 to 5 watts of output for consistent coverage.
Mobile radios (10 to 50 watts) have far better coverage, but require
more current, such as from a car battery or power supply. Most radios
have variable power settings to conserve power and battery capacity.
Handheld radios use sealed and rechargeable multi-cell battery packs
that fit a specific radio and are rarely interchangeable between models.
It is wise to purchase a spare pack and rotate the packs regularly.
Packs that hold regular alkaline AAA or AA cells are important to have
for operation away from home or in emergencies when recharging power
may not be available. (Remember to dispose of dead and weak battery
packs properly!) Several battery options are described in Table 3 (see
the PDF file).
The higher a battery's energy density, the longer a battery of a given
size will last. Energy density drops with temperature, so a cold battery
won't deliver as much energy as one at room temperature. Most batteries
are rated to be stored at temperatures from -20 to +45 degrees Celsius.
Handheld radios are sold with a wall-mounted
Handheld radios use sealed and rechargeable multi-cell battery packs that
fit a specific radio and are supply or "wall wart" that charges the
batteries (rarely interchangeable between models) slowly. This may be
inconvenient during emergency or heavy use. A desk or drop-in charger
charges the packs quickly and holds the radio upright. If the radio can
charge from 12 V, it can also be charged in a vehicle with an automotive
adapter. An automotive adapter that allows your handheld radio to charge
(and possibly operate) from a vehicle's cigarette lighter or other 12-volt
source is useful if ac power is unavailable. Not all handheld radios can
transmit while connected to chargers; be sure to check the manual!
Radios for base, portable, or mobile use require an external power source.
This may be a vehicle's electrical system, a deep-cycle battery, or an
ac-operated power supply. Mobile radios may require up to 20 amps on
transmit at full power, so be sure your power source can deliver enough current.
Power supplies and the cables used to connect the radio must be able to
supply the maximum required current for your radio at the proper voltage.
Check the radio's specifications for input current to find out how much
current is needed. The radio manual should also specify what wire size
for a given cable length is needed to insure adequate voltage at the
radio under full load.
--- SBBSecho 3.00-Win32
* Origin: The Thunderbolt BBS - wx1der.dyndns.org (57:57/10)
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