GLOSSARY
- Alpha: The current gain factor of a transistor connected in a common base
circuit. Alpha is equal to the ratio of collector current change to emitter
current change for a constant collector voltage.
- Amplitude Modulation (AM): Varying the amplitude of an r-f carrier in
accordance with intelligence.
- Beat Frequency: A frequency resulting from the combination of two different
frequencies. It is numerically equal to the difference between, or the sum
of, the two frequencies.
- Beta: The current gain factor of a transistor connected in a common-emitter
circuit, Beta is equal to the ratio of a change in collector current to a
change in base current for a constant collector voltage.
- Buffer Amplifier: An amplifier used to isolate the output of an oscillator
from the effects produced by changes in loading in the following stages.
- Calibration: The marked graduations of a dial, or any other indicator.
- Carrier: The r-f component of a transmitted wave upon which an audio signal
or other form of intelligence may be superimposed.
- Crystal: A natural substance, such as quartz, or tourmaline, which is
capable of producing pressure when under an applied voltage. Under stress
it has the property of responding only to a given frequency when cut to a
given thickness.
- De-Emphasis: A low-pass filter network consisting of an RC filter usually
connected at the output of an FM detector to shunt some of the higher audio
frequencies.
- Detection: The process of separating the modulation component from the
signal.
- Discriminator: A receiver circuit that removes the desired intelligence
from an FM signal by changing the frequency variations to amplitude variations.
- Field Strength: Electrical strength of a field.
- Frequency: The number of complete cycles per second existing in any form
of wave motion, such as the number of cycles per second of alternating current.
- Frequency Modulation (FM): A system of superimposing intelligence on a
carrier wave by causing the carrier frequency to vary in accordance with
the intelligence.
- Ground: A metallic connection with the earth to establish ground potential.
Also a common return to a point of zero r-f potential, such as the receiver
chassis.
- Heat Sink: A mass of metal or other good heat conductor used to rapidly
dissipate heat energy produced by a transistor.
- Limiting: Removal by electronic means of one or both extremities of a
waveform at a one determined level.
- Mercury Cell: A primary cell of zinc-mercury construction. featuring constant
voltage and relatively long lifetime.
- Neutralization: The process of nullifying the voltage fed back through
the interelectrode capacitance of an amplifier tube, by providing an equal
voltage of opposite phase.
- Phase: The time difference between any point on a cycle and the beginning
of that cycle.
- Propagation: The transmission of r-f energy through space.
- Radio Frequency: Any frequency of electrical energy capable of propagation
into space.
- Ratio Detector: An FM demodulator that splits the rectified voltages in
such a way that their ratio is directly proportional to the ratio of the
applied i-f voltages which vary with frequency.
- Relay: An electromechanical switch.
- S Curve: The shape of the response curve of an FM detector circuit.
- S Meter: A meter used to read and indicate the strength of the signal
being received.
- Sidebands: Frequencies, in addition to the carrier frequency, produced
by modulating the carrier with an audio signal.
- Single Sideband: A system of radio transmission in which one set of sidebands
(either upper or lower) is completely suppressed, and the carrier frequency
is partly or completely sup pressed.
- Standing Wave: A distribution of current and voltage on a transmission
line formed by two sets of waves traveling in opposite directions, and characterized
by the presence of a number of points of successive maximum and minimum values.
- Thermistor: A resistor whose resistance value changes inversely with temperature.
- Thermocouple: A junction of two dissimilar metals that produces a voltage
when heated by an r-f current.
- Transistor: A semiconductor device capable of transferring a signal from
one circuit to another and producing amplification.
- Tuning: The varying of an inductance or capacitance to control the resonant
frequency of a circuit.
- Voltage Regulation: A measure of the degree to which a power source maintains
its output voltage stability under varying load conditions.
- Wave: Basically, an electromagnetic impulse, periodically changing in
intensity and traveling through space.
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