- BNC connector
The BNC (Bayonet Neill Concelman) connector is a very common type of
RF connectorused for terminating coaxial cable.
The BNC connector is used for RF signal connections, for analog and
Serial Digital Interfacevideo signals, amateur radioantenna connections, aviation electronics ( avionics) and many other types of electronic test equipment. It is an alternative to the RCA connectorwhen used for composite video on commercial video devices, although many consumer electronicsdevices with RCA jacks can be used with BNC-only commercial video equipment via a simple adapter. BNC connectors were commonly used on 10base2thin Ethernetnetworks, both on cable interconnections and network cards, though these have largely been replaced by newer Ethernet devices whose wiring does not use coaxial cable. Some ARCNETnetworks use BNC-terminated coax.
BNC connectors exist in 50 and 75
ohmversions. Originally all were 50 ohm and were used with cables of other impedances, the small mismatch being negligible at lower frequencies. The 75 ohm types can be recognized by the reduced or absent dielectricin the mating ends. The different versions are designed to mate with each other, [http://www.amphenolconnex.com/products/bnc.asp Amphenol Connex - BNC Connector specifications] ] although the impedance mismatch will lead to signal reflections. Typically, they are specified for use at frequencies up to 4 and 2 GHz, respectively.
NOTE. The physical sizes of the 50 and 75
ohmsockets are slightly different and can damage the "wrong" plugs.
The connector was named after its
bayonet mountlocking mechanism and its two inventors, Paul Neillof Bell Labs(inventor of the N connector) and Amphenolengineer Carl Concelman(inventor of the C connector), and is much smaller than both the N and the C connectors. Other backronyms the BNC has picked up over the years include: "Baby Neill-Concelman", "Baby N connector", "British Naval Connector", "Bayonet Nut Connector".The basis for the development of the BNC connector was largely the work of Octavio M. Salati, a graduate of the Moore School of Electrical Engineering of the University of Pennsylvania (BSEE '36, PhD '63). He filed a patent in 1945 (granted 1951) while working at Hazeltine Electronics Corporation for a connector placed on coaxial cables that would minimize wave reflection/loss. [ [http://www.google.com/patents?id=6o9oAAAAEBAJ&printsec=abstract&zoom=4 Electrical connector] . US Patent 2,540,012 by Octavio M. Salati]
A threaded version of the BNC connector, known as the
TNC connector(for Threaded Neill-Concelman) is also available. It has superior performance to the BNC connector at microwavefrequencies.
BNC connectors are commonly used in
NIMelectronics, but they are now often replaced by LEMO00 miniature connectors which allow for higher densities. For higher voltages, MHV and SHV connectors are typically used. MHV connectors are easily mistaken for BNC connectors and can be made to mate with them by brute force. The SHV connector was developed as a safer alternative to MHV connectors and will not intermate with ordinary BNC connectors.
In USSR, BNC connectors were copied as SR-50 (Russian: СР-50) and SR-75 (Russian: СР-75) connectors. These connectors have slightly different dimensions (as a result of recalculating from Imperial to Metric system), but are generally interchangeable with BNC, sometimes with force applied.
Twin BNC connectors use the same bayonet latching shell as an ordinary BNC connector but contain two independent contact points (one male and one female), allowing the connection of a 78 ohm or 95 ohm shielded
differential pairsuch as RG-108A. [ [http://www.amphenolrf.com/products/twinbnc.asp Amphenol RF - Twin BNC connector series] ] They are capable of operation at 100 MHz and 100 volts. Twin BNC connectors will not intermate with ordinary BNC connectors.
Triaxial connectors are a variant on BNC which carry both a signal and guard as well as ground conductor. These are used in sensitive electronic measurement systems, particularly of Keithley manufacture. Early ones were designed with just an extra inner conductor, but later tri-axial connectors also include a three-lug arrangement to rule out an accidental forced mating with a BNC connector. Adaptors exist to allow some interconnection possibilities between tri-ax and BNC connectors.
BNC inserter/remover tool
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