18WuD2x

unsaturated standard cell • ununoctium 713
Collector current
Unsaturated
operation
Base voltage
unsaturated operation
Saturation
point
unsaturated standard cell See STANDARD CELL.
unshielded cable A cable, such as a twisted pair or
a multiwire twist, lacking a shielding jacket. Unless
special precautions are taken, such as transposing
conductors, such a cable is susceptible to
stray pickup and is capable of radiation.
unshielded choke An uncased choke (i.e., one without
a protective and shielding metal housing).
unshielded coil An inductor without a fieldconfining
enclosure.
unshielded probe An instrument probe that has no
shielding enclosure. Such a probe is desirable for
some tests, but it is subject to antenna-pickup effect,
body capacitance, and stray-field pickup.
unshielded stage In electronic equipment, a stage
operating entirely in the open (i.e., without electrostatic
or magnetic shielding enclosures). It is,
therefore, susceptible to stray pickup and is capable
of radiation.
unshielded transformer 1. An uncased transformer
(i.e., one without a protective and shielding
metal housing). 2. A transformer having no
electrostatic shield between its windings.
unshift The mechanical action in a teletypewriter
when the carriage moves from the figures position
to the letters position.
unshunted current meter A single-range
D’Arsonval milliammeter or microammeter that
has no shunt resistor. The resistance of the instrument
is, therefore, equal to the resistance of
the movable coil.
unsolder To separate wires, contacts, or fastenings
by melting the solder that holds them together.
Also called DESOLDER.
unsophisticated electronics Electronics theory
and operations of the simplest kind, involving little
or no mathematics. It is generally intended for
a hobbyist audience. Compare SOPHISTICATED
ELECTRONICS.
unstable oscillation 1. Relaxation oscillation.
2. The periodically interrupted oscillation characteristic
of a blocking oscillation.
unstable region The negative-resistance portion of
an N- or S-shaped response curve.
unstable servo A servo having unlimited output
drift.
unstable state A condition, such as a negativeresistance
region, that is difficult to maintain
and often results in oscillation. The negativeresistance
region of the tunnel diode forwardconduction
curve is evidence of such a state.
Compare STABLE STATE.
untapped winding A winding having two terminals,
one at either end, and no intermediate terminals
or connections. Also called untapped coil.
unterminated amplifier An amplifier operated
without a load device (i.e., under open-circuit
output conditions).
unterminated generator A generator operated
without a load device (i.e., under open-circuit
output conditions).
unterminated line A transmission line that is not
terminated with an impedance (i.e., an openended
line).
untriggered flip-flop A flip-flop that, at a particular
instant, receives no actuating pulse, and that,
therefore, does not change state.
untuned amplifier A radio-frequency amplifier
that is not tuned to a single frequency, but has
useful gain over a wide band of frequencies. Examples
are the distributed amplifier and the video
amplifier.
untuned filter See ALL-PASS FILTER.
untuned line An aperiodic transmission line (i.e.,
one that is only tuned to a particular frequency
by its own distributed characteristics).
untuned transformer A transformer having simple
primary and secondary windings and no tuning
devices (such as capacitors in series or
parallel with the windings), and designed so that
its natural resonant frequency (because of distributed
capacitance) lies outside the specified
range of operation.
ununbium Symbol, Uub. Atomic number, 112.
The most common isotope has atomic weight
277. Classified as a transition metal. It is humanmade
and not known to occur in nature.
ununhexium Symbol, Uuh. Atomic number, 116.
The most common isotope has atomic weight
289. First reported in January 1999. It is a decomposition
product of ununoctium, and it in
turn decomposes into ununquadium. It is not
known to occur in nature.
ununnilium Symbol, Uun. Atomic number, 110.
The most common isotope has atomic weight
269. Classified as a transition metal. It is
human-made and not known to occur in
nature.
ununoctium Symbol, Uuo. Atomic number, 118.
The most common isotope has atomic weight
293. It is the result of the fusion of krypton and
lead, and decomposes into ununhexium. It is not
known to occur in nature.