18WuD2x

698 tunnel-diode amplifier • two-phase
to produce gain. It is used primarily at ultra-high
and microwave frequencies.
tunnel-diode oscillator A circuit that uses the
negative-resistance properties of a tunnel diode
to produce oscillation at a specific frequency. It is
used primarily at ultra-high and microwave frequencies.
turbidimeter A device used to measure the turbidity
(relative opaqueness) of liquids.
turbidity meter See TURBIDIMETER.
Turing machine A hypothetical model, conceived
by Alan Turing in the 1930s, devised as an exercise
in problem solving. In effect, it was a computer
programming language with a limited
instruction set, operating in a computer with infinite
memory and storage capacity.
Turing test A scheme devised by Alan Turing, designed
to test computers for artificial intelligence
(AI). If the machine can fool a person into thinking
it is another person most of the time, then the
machine in effect “passes” the test, indicating
that it has some AI.
turn One complete loop of a coil.
turnaround time 1. The length of time required for
a repair to be performed. 2. The length of time required
for a computer program to be completed.
3. The time required for a trans-ceiver to switch
from the full-transmit to the full-receive condition.
turn factor For a given inductor core, the number
of turns (in a standard configuration) that results
in an inductance of 1 H.
turn-off time The time required for the operation
of a circuit or device to cease completely after a
signal or operating power has been removed.
Compare TURN-ON TIME.
turn-on time The time required for a circuit or device
to come up to full (normal) operation after
application of a trigger or operating power. Compare
TURN-OFF TIME.
turnover pickup See DUAL PICKUP.
turns ratio For a transformer, the ratio of the
number of turns in the primary winding to the
number of turns in the secondary winding.
turnstile antenna A polyphase antenna that resembles
a turnstile gate.
turntable 1. The motor-driven, rotating platter on
which a phonograph disc rests during recording
or reproduction. 2. In a high-fidelity phonograph
system, the assembly containing the platter, as
defined in 1.
turret tuner A television front-end tuner having a
separate tuned-circuit section for each channel.
Turning a knob rotates a desired section into position
against switch contacts. Also called DE-
TENT TUNER.
TV 1. Abbreviation of TELEVISION. 2. Abbreviation
of terminal velocity.
T/V Abbreviation of temperature to voltage.
TV decoder A device for unscrambling a television
broadcast that has been intentionally encrypted
to prevent its use by unauthorized viewers. See
SUBSCRIPTION TV.
TV ghost See GHOST.
TVI Abbreviation of TELEVISION INTERFERENCE.
TVL Amateur radio abbreviation of television listener
(looker).
TVM Abbreviation of TRANSISTORIZED VOLT-
METER.
TVO Abbreviation of TRANSISTORIZED VOLT-
OHMMETER. (Also, TVOM.)
TVOM Abbreviation of TRANSISTORIZED VOLT-
OHMMETER. (Also, TVO.)
TV projector A combination electronic and optical
device for projecting television images on a large
screen.
TV sound marker See SOUND MARKER.
TVT Abbreviation of television terminal (computer
peripheral).
TW Abbreviation of TERAWATT.
TWA Abbreviation of TRAVELING-WAVE AMPLI-
FIER.
tweeter A loudspeaker that favors the extreme treble
(high) audio frequencies, ranging from 4000
or 5000 Hz to more than 20,000 Hz. Compare
WOOFER.
twin diode See DUAL DIODE.
twinlead See FLAT-RIBBON LINE.
twin line See FLAT-RIBBON LINE.
twin meter See DUAL METER.
twin-T measuring circuit See PARALLEL-TEE
MEASURING CIRCUIT.
twin-T network See PARALLEL-TEE NETWORK.
twisted pair A simple wire line used for communications.
It consists of two wires twisted together
to form a helix.
twister A piezoelectric crystal, such as one of
Rochelle salt, that generates a voltage when
torqued.
twistor A magnetic-memory element consisting of
a winding of magnetic wire on a length of nonmagnetic
wire.
two-channel amplifier See DUAL-CHANNEL AM-
PLIFIER.
two-channel recorder See DOUBLE-CHANNEL
RECORDER.
two-electrode amplifier See DIODE AMPLIFIER.
two-electrode tube See TUBE DIODE.
two-element amplifier See DIODE AMPLIFIER.
two-element beam A Yagi antenna consisting of a
driven element and one parasitic element. The
parasitic element can be either a reflector, about
5% longer than the resonant half wavelength at
the operating frequency, or it can be a director,
about 5% shorter than a half wavelength at the
operating frequency.
two-element tube An electron tube having two
principal electrodes (i.e., a tube diode).
two-five code See BIQUINARY CODE.
two-phase Pertaining to circuits or devices in
which two components (two voltages, two