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The SGC Building, 13737 S.E. 26th St. Bellevue, Washington 98005 USA
P.O. Box 3526, 98009 Tel: (206) 746-6310 Fax: (206) 746-6384
© 1997 SGC Inc.
The selectivity of a radio receiver is its ability to distinguish between signals that are audible on the frequency
that the radio is tuned to and other signals across the radio spectrum. Sensitivity is especially important when you
are listening to crowded parts of the radio spectrum. If this is the case, you will hear one station on a radio with
good selectivity and many stations (or images of stations) on a receiver with poor selectivity.
The operating temperature range of a transceiver is simply the temperature range that it will operate within.
This measure is especially important when the equipment is to be used in extreme climates, such as in subzero or
high temperatures near the equator.
The power requirements of a radio refer to the voltage that it requires to operate. This voltage requirement is
important because it will determine the power source that can operate the radio. Some of the common ratings are
220 and 110 volts (for operation from the main power lines) and 12 and 24 volts (for operation from a battery pack).
The current draw refers to the amount of power that a radio requires while operating. The equation W = I xV
shows the relationship between the voltage, the wattage, and the current draw, where W is the power in watts, I is
the current in amps, and V is the voltage in volts. For any radio that you use, V will be constant. When the voltage is
constant, and the radio requiring more watts when receiving than transmitting, you can determine the difference in
the current draw.
SELECTIVITY
OPERATING TEMPERATURE RANGE
POWER REQUIREMENTS
CURRENT DRAW
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