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PL-259 (male) plug. Outside diameter is about 18 mm.
|Type||RF coaxial connector|
|Designer||E. Clarke Quackenbush|
|Diameter||18 mm (0.71 in) (typical)|
|Passband||Typically 0-100 MHz|
PL-259 (plug) 
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.
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.
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.
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.
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.
The UHF connector is not weatherproof.
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.
- US patent 2761110, Henry M Diambra, "Solderless Coaxial Connector", published 1956-08-28, assigned to Entron, Inc.
- US patent 4085366, Billy Padgett, "Noise reduction device for citizen's band transceivers", published 1978-04-18, assigned to Billy Padgett
- "UHF Connector Series". Amphenol. Retrieved 23 September 2015.
- US patent 2335041, William A Bruno, "Right-angle electric connector", published 1943-11-23, assigned to Bruno Patents Inc
- US patent 2422982, Edward Clarke Quackenbush, "Coaxial cable connector", published 1947-06-24, assigned to Edward Clarke Quackenbush
- Dale Pollack (1941). "High-Frequency Transmission and Reception". In Henney, Keith. Radio Engineering Handbook (3rd ed.). New York and London: McGraw-Hill Book Company. p. 514.
- "(PL) 259 Connectors". Connectors. Hamradio.me. July 2011. Retrieved 16 May 2015.
- "Introduction to U.H.F.". The Radio Amateur's Handbook (18th ed.). West Hartford, CT: American Radio Relay League. 1941. pp. 362–363.
In Amateur work, the ultra-high-frequency region is considered to include the 56 to 60 Mc band and all higher frequency bands available for amateur use.
- "'UHF' Connector Test Results". Connectors. Hamradio.me. October 2011. Retrieved 31 January 2012.
- TM 11-5820-348-15, ANTENNA EQUIPMENT RC-292. Department of the Army. 1966-04-23.
- MIL-HDBK 172A, Vol. I - Military Standardization Handbook, Electronic Test Equipment. Department of Defense. 1964-03-11.
- "Drawing of Metric Connector". RF Supplier. Retrieved 24 September 2015.
- US patent 2233166, William C Hahn, "Means for transferring high frequency power", published 1941-02-25, assigned to Gen Electric
- "The UHF type connector under network analysis". Chris's Amateur Radio and Electronics resource pages. Retrieved 31 January 2012.
[. . .] at 432 MHz [. . .] we see a loss in the order of 1.0 dB, this equates to a transmission loss of around 6 Watts with 25 Watts input.
- "Lab Tests: SMA, BNC, TNC and N Connectors". Connectors. Hamradio.me. August 2011. Retrieved 31 January 2012.