ORIGINThe point on a graph where the vertical and horizontal axes cross each other .
OSCILLATORAn oscillator is a nonrotating device that produces alternating current. The frequency is
determined by the characteristics of the device .
OUT-OF-CIRCUIT METERA meter that is not permanently installed in a circuit. Usually portable and
self-contained, these meters are used to check the operation of a circuit or to isolate troubles within a
OUTPUT ENDThe end of a transmission line that is opposite the source; receiving end .
OUTPUT IMPEDANCEThe impedance that is presented to the load by the transmission line and its
OVERDRIVENWhen the input signal amplitude is increased to the point that the transistor goes into
saturation and cutoff .
OVERMODULATIONA condition that exists when the peaks of the modulating signal are limited .
PACKAGING LEVELSA system developed to assist maintenance personnel in determining the
repairability of components, printed circuit boards, modules, and so forth .
PAGE PRINTERA high-speed printer that prints teletypewriter characters one at a time in a full-page
PARABOLIC REFLECTORAn antenna reflector in the shape of a parabola. It converts spherical
wavefronts from the radiating element into plane wavefronts .
PARALLAX ERRORThe error in meter readings that results when you look at a meter from some
position other than directly in line with the pointer and meter face. A mirror mounted on the meter face
aids in eliminating parallax error .
PARALLEL CIRCUITTwo or more electrical devices connected to the same pair of terminals so
separate currents flow through each; electrons have more than one path to travel from the negative to
the positive terminal .
PARALLEL-CONNECTED DUPLEXERConfiguration in which the tr spark gap is connected across
the two legs of the transmission line one-quarter wavelength from the T-junction .
PARALLEL LIMITERA resistor and diode, connected in series with the input signal, in which the
output is taken across (parallel to) the diode .
PARALLEL-NEGATIVE LIMITERA resistor and diode, connected in series with the input signal, in
which the output is taken across the diode and the negative alternation is eliminated 
PARALLEL-POSITIVE LIMITERA resistor and diode connected in series with the input signal, in
which the output is taken across the diode and the positive alternation is eliminated .
PARALLEL-RESONANT CIRCUITA resonant circuit in which the source voltage is connected across
a parallel circuit (formed by a capacitor and an inductor) to furnish a high impedance to the frequency
at which the circuit is resonant. Often referred to as a tank circuit  .
PARALLEL-WIREA type of transmission line consisting of two parallel wires .