U

UG (symbol) Used to describe coaxial connectors that are made to a Government Specification.

uhf (abbreviation) See ultra-high frequency.

UL - Abbreviation for Underwriters Laboratories, a non-profit independent organization that operates a listing service for electrical and electronic materials and equipment.   An independent laboratory that tests equipment to determine whether it meets certain safety standards when properly used.

Ultra-High Frequency (UHF)--A Federal Communications Commission designation for the band from 300 to 3000 MHz on the radio spectrum. In television - channels 14 to 83 or 470 to 890 MHz.

ultrasonic bond (process) A joining of materials achieved by the scrubbing action and energy transfer of a tool vibrating at an ultrasonic frequency. Attaching leads to pads on silicon devices, and achieving bonds between dissimilar metals are two common applications of this process.

See also ultrasonic welding.

ultrasonic welding (process) Process using vibratory mechanical pressure at ultrasonic frequencies (20 to 40 kHz) to provide heat for welding some types of thermoplastics.

See also ultrasonic bond.

ultraviolet curing (process) Process of accomplishing complete cross-linkage of a polymer coating or other product using ultraviolet light on the work piece.

umbilical connector (component) Used to connect ground support cables to a rocket or missile, and is then disconnected from the missile at the time of launching.

Unilay - Cable with more than one layer of conductors with direction of lay and lay length the same for all layers.

UTP --Unshielded Twisted Pair. Twisted pair cable without either individual or overall shielding.

UV (abbreviation) Ultraviolet.