Type RF coaxial connector Designed 1930s Cable Coaxial | Designer E. Clarke Quackenbush Manufacturer Various | |
 | ||
Diameter 18 mm (0.71 in) (typical) | ||
The UHF connector is a World War II or earlier threaded RF connector design, from an era when "UHF" referred to frequencies over 30 MHz. Originally intended for use as a video connector in radar applications, the connector was later used for other RF applications. This connector was developed on basis of a shielded banana plug.
Contents
Design and nomenclature
Originally the connector was designed to carry signals at frequencies up to 300 MHz, but later measurements reveal limitations above 100 MHz. The coupling shell has a 5⁄8 inch 24tpi UNEF standard thread. The most popular cable plug and corresponding chassis-mount socket carry the old Signal Corps nomenclatures PL-259 (plug) and SO-239 (socket). These are also known as Navy type 49190 and 49194 respectively.
PL-259, SO-239, and several other related military references refer to one specific mechanical design collectively known as the UHF Connector.
Mechanical
By design, all connectors in the UHF Connector family mate using the 5/8 inch 24 tpi threaded shell for the shield connection and an approximately 0.156 inch (4mm) diameter pin and socket for the inner conductor. Similar connectors with an incompatible 16mm diameter, 1mm metric thread have been produced, but these are not standard UHF connectors by definition.
Surge impedance
UHF connectors have a non-constant surge impedance. For this reason, UHF connectors are generally usable through HF and the lower portion of what is now known as the VHF frequency range. Despite the name, the UHF connector is rarely used in commercial applications for today's UHF frequencies, as the non-constant surge impedance creates measurable electrical signal reflections above 100 MHz.
Power
UHF connectors can handle RF peak power levels over one kilowatt based on the voltage rating of 500 volts peak. The average power handling of the PTFE-insulated versions is essentially set by heating of the center pin, and is therefore frequency-dependent, because the RF resistance rises as the skin depth falls.
Environmental tolerance
The UHF connector is not weatherproof.
Applications
In many applications, UHF connectors were replaced by designs that have a more uniform surge impedance over the length of the connector, such as the N connector and the BNC connector. UHF connectors are still widely used in amateur radio, Citizens Band radio, and marine VHF radio applications.