UHF connector

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UHF connector
PL-259 (male) plug. Outside diameter is about 18 mm.
Type RF coaxial connector
Designer E. Clarke Quackenbush[citation needed]
Designed 1930s
Manufacturer Various
Diameter 18 mm (0.71 in) (typical)
Cable Coaxial
Passband Typically 0-100 MHz
Connector SO-239 (socket)[1]
PL-259 (plug) [2]
"Classic" UHF connector with a soldered center pin. The fringe of braided shielding at the rear has not been fully trimmed away.
Adaptor from SO-239 to BNC connector

The UHF connector[3] is a World War II or earlier[4][5] threaded RF connector design, from an era when "UHF" referred to frequencies over 30 MHz.[6][7][8] Originally intended for use as a video connector in radar applications, the connector was later used for other RF applications.[citation needed] This connector was developed on basis of a shielded banana plug.[citation needed]

Design and nomenclature[edit]

Originally the connector was designed to carry signals at frequencies up to 300 MHz,[3] but later measurements reveal limitations above 100 MHz.[9] The coupling shell has a 58 inch 24tpi UNEF standard thread.[3] The most popular cable plug and corresponding chassis-mount socket carry the old Signal Corps nomenclatures PL-259 (plug) and SO-239 (socket).[10] These are also known as Navy type 49190 and 49194 respectively.[11]

PL-259, SO-239, and several other related military references refer to one specific mechanical design collectively known as the UHF Connector.[3]



By design, all connectors in the UHF Connector family mate using the 5/8 inch 24 tpi threaded shell for the shield connection[3] and an approximately 0.156 inch (4mm) diameter pin and socket for the inner conductor.[citation needed] Similar connectors with an incompatible 16mm diameter, 1mm metric thread have been produced,[12] but these are not standard UHF connectors by definition.[3]

Surge impedance[edit]

UHF connectors have a non-constant surge impedance.[3] For this reason, UHF connectors are generally usable through HF and the lower portion of what is now known as the VHF frequency range.[9] 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.[9][13][14]


UHF connectors can handle RF peak power levels over one kilowatt based on the voltage rating of 500 volts peak.[3] 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.[citation needed]

Environmental tolerance[edit]

The UHF connector is not weatherproof.[3]


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.[15] UHF connectors are still widely used in amateur radio, Citizens Band radio, and marine VHF radio applications.[citation needed]

See also[edit]


  1. ^ US patent 2761110, Henry M Diambra, "Solderless Coaxial Connector", published 1956-08-28, assigned to Entron, Inc. 
  2. ^ US patent 4085366, Billy Padgett, "Noise reduction device for citizen's band transceivers", published 1978-04-18, assigned to Billy Padgett 
  3. ^ a b c d e f g h i "UHF Connector Series". Amphenol. Retrieved 23 September 2015. 
  4. ^ US patent 2335041, William A Bruno, "Right-angle electric connector", published 1943-11-23, assigned to Bruno Patents Inc 
  5. ^ US patent 2422982, Edward Clarke Quackenbush, "Coaxial cable connector", published 1947-06-24, assigned to Edward Clarke Quackenbush 
  6. ^ 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. 
  7. ^ "(PL) 259 Connectors". Connectors. Hamradio.me. July 2011. Retrieved 16 May 2015. 
  8. ^ "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. 
  9. ^ a b c "‘UHF’ Connector Test Results". Connectors. Hamradio.me. October 2011. Retrieved 31 January 2012. 
  10. ^ TM 11-5820-348-15, ANTENNA EQUIPMENT RC-292. Department of the Army. 1966-04-23. 
  11. ^ MIL-HDBK 172A, Vol. I - Military Standardization Handbook, Electronic Test Equipment. Department of Defense. 1964-03-11. 
  12. ^ "Drawing of Metric Connector". RF Supplier. Retrieved 24 September 2015. 
  13. ^ US patent 2233166, William C Hahn, "Means for transferring high frequency power", published 1941-02-25, assigned to Gen Electric 
  14. ^ "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. 
  15. ^ "Lab Tests: SMA, BNC, TNC and N Connectors". Connectors. Hamradio.me. August 2011. Retrieved 31 January 2012. 

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