AIR-CORE TRANSFORMERA transformer composed of two or more coils that are wound around a
nonmetallic core .
ALLOWANCE PARTS LIST (APL)Repair parts required for units having the equipment/ component
ALLOYED JUNCTIONA junction formed by recrystallization of a molten region of P-type material on
an N-type substrate, or vice versa .
ALPHAThe emitter-to-collector current gain in a common-base circuit .
ALTERNATING CURRENTAn electrical current that constantly changes amplitude and changes
polarity at regular intervals .
ALTITUDEThe vertical distance of an aircraft or object above a given reference, such as ground or sea
ALUMINUM CREEP(1) The movement of aluminum wire from a point where pressure is applied. (2)
The "retreat" of heated aluminum wire as it cools .
AMBIENT TEMPERATUREThe surrounding temperature such as the temperature of air surrounding a
conductor in a compartment or within a piece of equipment .
AMBIGUOUS RETURNSEchoes that exceed the prt of a radar and appear at incorrect ranges .
AMERICAN WIRE GAUGE (AWG)The standards adopted in the United States for the measurement of
wire sizes .
AMMETERAn instrument for measuring the amount of electron flow (in amperes)   .
AMPEREThe basic unit of electrical current .
AMPERE-TURNThe magnetomotive force developed by 1 ampere of current flowing through a coil of
one turn .
AMPERITE (BALLAST) TUBEA current-controlling resistance device designed to maintain
substantially constant current over a specified range of variation in applied voltage or resistance of a
series circuit .
AMPLIDYNEA special dc generator in which a small dc voltage applied to field windings controls a
large output voltage from the generator. In effect, an amplidyne is a rotary amplifier that often times
produces gain of approximately 10,000 .
AMPLIFICATION(1) The process of enlarging a signal in amplitude (as of voltage or current) . (2)
The ratio of output magnitude to input magnitude in a device that is intended to produce an output that
is an enlarged reproduction of its input  .
AMPLIFICATION FACTORThe voltage gain of an amplifier with no load on the output  .
AMPLIFIERThe device that provides amplification (the increase in current, voltage, or power of a
signal) without appreciably altering the original signal  .
AMPLITRONSee CROSS-FIELD AMPLIFIER .