18WuD2x

60 balanced method • balun
balanced method A system of instrumentation in
which a zero-center scale is used. The reading
can be either side of the zero reading.
balanced modulator A symmetrical modulator circuit
using bipolar transistors, field-effect transistors,
an integrated circuit, or diodes as principal
components, that delivers an output signal containing
the sidebands, but not the carrier. It is
commonly used to generate a double-sideband
(DSB) signal that can be filtered to obtain a
single-sideband (SSB) signal.
balanced multivibrator A switching oscillator circuit
in which the two halves are identical in configuration,
and as nearly identical as practicable
in performance.
balanced network Any network intended to be
used with a balanced system or balanced transmission
line. It is characterized by a pair of terminals,
each of which shows the same impedance
with respect to ground.
balanced oscillator A PUSH-PULL OSCILLATOR.
balanced output Output balanced against ground
(e.g., where the electrical midpoint of the output
circuit is grounded).
balanced output transformer 1. A push-pull output
transformer with a center-tapped primary
winding. 2. An output transformer with a
grounded center tap on its secondary winding.
Input
balanced output transformer, 2.
Output
balanced probe A probe, such as one for an electronic
voltmeter or oscilloscope, that has a balanced
input and (usually) a single-ended output.
balanced-tee trap A wavetrap constructed in a T
configuration, with a resonant section in each
conductor of a balanced transmission line.
balanced telephone line A telephone transmission
line that has two sides, similar to a balanced
radio-frequency transmission line. Either side
has the same impedance, with respect to ground.
balanced termination A load device (or the practice
of using such a device) in which the sections
provide identical termination for each of the sections
or conductors of a balanced system, such
as a balanced line.
balanced-to-unbalanced transformer See BALUN.
balanced transmission line See BALANCED LINE.
balanced varactor tuning A two-varactor, backto-back
circuit for adjusting the value of a capacitor
using an applied dc voltage. This
arrangement has an advantage over a singlevaractor
(unbalanced) circuit, because hightuned-circuit
Q is maintained and harmonic
generation is reduced.
balanced voltages In any symmetrical system,
such as a balanced line or push-pull circuit, two
or more input or output voltages that are adjusted
to have the same amplitude and (usually)
opposite phase.
balanced-wire circuit A circuit or conductor system
with identical halves that are symmetrical,
with respect to ground and to other conductors.
balancing circuit See BUCKING CIRCUIT.
balancing coil In a receiver, a center-tapped antenna
coil that is balanced to ground to eliminate
MARCONI EFFECT.
ballast 1. A component that is used to stabilize the
current flow through, or operation of, a circuit,
stage, or device. 2. An iron-core choke connected
in series with one of the electrodes in a fluorescent
or other gas-discharge lamp.
ballast resistor 1. A nonlinear inductive power resistor
whose voltage-current (EI) characteristic is
such that current through the resistor is independent
of voltage over a useful range. This feature
enables the ballast resistor to act as an
automatic voltage regulator when it is simply
connected in series with a power supply and load.
2. A small (usually high-resistance) resistor operated
in series with a glow lamp, such as a neon
lamp, to prevent overload.
ballast transformer A misnomer often used in
place of BALLAST, 2.
ballistic galvanometer An undamped galvanometer
that is used particularly to observe electric
charges by noting the single throw resulting
from the momentary flow of current through the
galvanometer coil.
ballistics The electronics-supported science concerned
with the motion of projectiles and similar
bodies in air or space.
balloon antenna A vertical antenna consisting of a
wire or wires held aloft by a captive balloon. Occasionally,
used by radio amateurs and shortwave
listeners at low and medium frequencies. A potentially
dangerous antenna because of large staticelectric
buildup, a tendency to attract lightning,
the possibility of its breaking loose, and the risk of
accidental contact with high-voltage power lines.
balop Contraction of BALOPTICON.
balopticon An opaque-picture projecting system in
which the picture is viewed by a television (TV)
camera, such as a vidicon, and displayed by a
picture tube. Also called balop.
balun A specialized impedance-matching radiofrequency
(RF) transformer. It is a wideband device,