UHF connector
Encyclopedia
The UHF connector, also called the Amphenol
coaxial connector,
is a World War II
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,
it was later used for RF
applications. This connector was developed on basis of a shielded banana plug.
UHF connectors are generally usable through what is now known as the VHF
and HF
frequencies and can handle RF power levels over one kilowatt.There is variation between manufacturers with the choice of dielectric, the PTFE types being favoured where low loss is desired. The average power handling of the PTFE versions is essentially set by heating of the centre pin, and is therefore frequency dependent, as the RF resistance rises as the skin depth falls. At low frequencies the power handling is rather better than that of the similar sized N connector
. The UHF connector is the most common connector in amateur radio
applications and is used in this application silver-plated with Teflon dialectric for UHF
applications up to 450 Mhz for the 70cm band.
Despite the name, it is rarely used in commercial applications for UHF frequencies as the non-constant impedance (the impedance drops to 30-40 ohms for a cm or so in the central region of the connector) means they create significant reflections above 300 MHz.
The most popular cable plug and chassis-mount socket carry the old Signal Corps nomenclatures PL-259 (plug) and SO-239 (socket). The PL-259 can be used with large diameter coaxial cable
, such as RG-8/U and RG-9/U, and the smaller diameter RG-58/U and RG-59/U with the UG-175/U and UG-176/U adapter sleeves. Technically, "PL-259" refers to one specific mechanical design, but the term is often used for any UHF cable plug. The thread is usually 5/8 inch 24tpi UNEF standard, however, UHF connectors with a similar, metric, thread have been produced. The center conductor jack on the SO-239 will also accept a 4mm banana plug.
UHF connectors were replaced in many applications by designs that have a more uniform impedance
over the length of the connector, such as the N connector
and the BNC connector
, but they are still widely used in amateur radio
, citizens' band radio
, and marine VHF radio
where robustness and ease of use are more important than a small mismatch. The reasons for the popularity of the UHF connector is its ease of assembly. While crimp connectors exist, the solderable screw-on connector is more common because no expensive crimping tools are required. The connector is not suitable for outdoor applications by itself but can be made weather resistant with self adhesive silicone C-Tape.
UHF connectors were also used for the input & output of composite video
signals for older video equipment (such as VTRs & monitor
s) dating from the late 1970s and earlier. They were known by BBC engineers as 'F & E' connectors, after Films & Equipment, a manufacturer.
Amphenol
Amphenol Corporation is a major producer of electronic and fiber optic connectors, cable and interconnect systems such as Coaxial cables. Amphenol is a portmanteau from the corporation's original name, American Phenolic Corp....
coaxial connector,
is a World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
threaded RF connector
RF connector
A coaxial RF connector is an electrical connector designed to work at radio frequencies in the multi-megahertz range.RF connectors are typically used with coaxial cables and are designed to maintain the shielding that the coaxial design offers. Better models also minimize the change in transmission...
design, from an era when
UHF
Ultra high frequency
Ultra-High Frequency designates the ITU Radio frequency range of electromagnetic waves between 300 MHz and 3 GHz , also known as the decimetre band or decimetre wave as the wavelengths range from one to ten decimetres...
referred to frequencies over 30 MHz.
Originally intended for use as a video
Video
Video is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.- History :...
connector in RADAR
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
applications,
it was later used for RF
Radio frequency
Radio frequency is a rate of oscillation in the range of about 3 kHz to 300 GHz, which corresponds to the frequency of radio waves, and the alternating currents which carry radio signals...
applications. This connector was developed on basis of a shielded banana plug.
UHF connectors are generally usable through what is now known as the VHF
Very high frequency
Very high frequency is the radio frequency range from 30 MHz to 300 MHz. Frequencies immediately below VHF are denoted High frequency , and the next higher frequencies are known as Ultra high frequency...
and HF
Shortwave
Shortwave radio refers to the upper MF and all of the HF portion of the radio spectrum, between 1,800–30,000 kHz. Shortwave radio received its name because the wavelengths in this band are shorter than 200 m which marked the original upper limit of the medium frequency band first used...
frequencies and can handle RF power levels over one kilowatt.There is variation between manufacturers with the choice of dielectric, the PTFE types being favoured where low loss is desired. The average power handling of the PTFE versions is essentially set by heating of the centre pin, and is therefore frequency dependent, as the RF resistance rises as the skin depth falls. At low frequencies the power handling is rather better than that of the similar sized N connector
N connector
The N connector is a threaded RF connector used to join coaxial cables. It was one of the first connectors capable of carrying microwave-frequency signals, and was invented in the 1940s by Paul Neill of Bell Labs, after whom the connector is named.-Design:Originally, the connector was designed to...
. The UHF connector is the most common connector in amateur radio
Amateur radio
Amateur radio is the use of designated radio frequency spectrum for purposes of private recreation, non-commercial exchange of messages, wireless experimentation, self-training, and emergency communication...
applications and is used in this application silver-plated with Teflon dialectric for UHF
Ultra high frequency
Ultra-High Frequency designates the ITU Radio frequency range of electromagnetic waves between 300 MHz and 3 GHz , also known as the decimetre band or decimetre wave as the wavelengths range from one to ten decimetres...
applications up to 450 Mhz for the 70cm band.
Despite the name, it is rarely used in commercial applications for UHF frequencies as the non-constant impedance (the impedance drops to 30-40 ohms for a cm or so in the central region of the connector) means they create significant reflections above 300 MHz.
The most popular cable plug and chassis-mount socket carry the old Signal Corps nomenclatures PL-259 (plug) and SO-239 (socket). The PL-259 can be used with large diameter coaxial cable
Coaxial cable
Coaxial cable, or coax, has an inner conductor surrounded by a flexible, tubular insulating layer, surrounded by a tubular conducting shield. The term coaxial comes from the inner conductor and the outer shield sharing the same geometric axis...
, such as RG-8/U and RG-9/U, and the smaller diameter RG-58/U and RG-59/U with the UG-175/U and UG-176/U adapter sleeves. Technically, "PL-259" refers to one specific mechanical design, but the term is often used for any UHF cable plug. The thread is usually 5/8 inch 24tpi UNEF standard, however, UHF connectors with a similar, metric, thread have been produced. The center conductor jack on the SO-239 will also accept a 4mm banana plug.
UHF connectors were replaced in many applications by designs that have a more uniform impedance
Electrical impedance
Electrical impedance, or simply impedance, is the measure of the opposition that an electrical circuit presents to the passage of a current when a voltage is applied. In quantitative terms, it is the complex ratio of the voltage to the current in an alternating current circuit...
over the length of the connector, such as the N connector
N connector
The N connector is a threaded RF connector used to join coaxial cables. It was one of the first connectors capable of carrying microwave-frequency signals, and was invented in the 1940s by Paul Neill of Bell Labs, after whom the connector is named.-Design:Originally, the connector was designed to...
and the BNC connector
BNC connector
The BNC connector ' is a common type of RF connector used for coaxial cable. It is used with radio, television, and other radio-frequency electronic equipment, test instruments, video signals, and was once a popular computer network connector. BNC connectors are made to match the characteristic...
, but they are still widely used in amateur radio
Amateur radio
Amateur radio is the use of designated radio frequency spectrum for purposes of private recreation, non-commercial exchange of messages, wireless experimentation, self-training, and emergency communication...
, citizens' band radio
Citizens' band radio
Citizens' Band radio is, in many countries, a system of short-distance radio communications between individuals on a selection of 40 channels within the 27-MHz band. Citizens' Band is distinct from the FRS, GMRS, MURS and amateur radio...
, and marine VHF radio
Marine VHF radio
Marine VHF radio is installed on all large ships and most seagoing small craft. It is used for a wide variety of purposes, including summoning rescue services and communicating with harbours, locks, bridges and marinas, and operates in the VHF frequency range, between 156 to 174 MHz...
where robustness and ease of use are more important than a small mismatch. The reasons for the popularity of the UHF connector is its ease of assembly. While crimp connectors exist, the solderable screw-on connector is more common because no expensive crimping tools are required. The connector is not suitable for outdoor applications by itself but can be made weather resistant with self adhesive silicone C-Tape.
UHF connectors were also used for the input & output of composite video
Composite video
Composite video is the format of an analog television signal before it is combined with a sound signal and modulated onto an RF carrier. In contrast to component video it contains all required video information, including colors in a single line-level signal...
signals for older video equipment (such as VTRs & monitor
Composite monitor
A composite monitor is any analog video display that receives input in the form of an analog composite video signal through a single cable — in contrast to multiple-cable or multiple-wire video sources such as VGA cable...
s) dating from the late 1970s and earlier. They were known by BBC engineers as 'F & E' connectors, after Films & Equipment, a manufacturer.