BNC connector

BNC (from Bayonet Neill–Concelman, sometimes erroneously referred to as the Bayonet Naval Connector or the Baby N Connector) is the most common coaxial connector standard for measurement equipment up to 1 GHz.

"Female" BNC connector

Patented in 1951 by Hazeltine Research, Inc, it is available in different impedances, with 50 Ω being by far the most common. A 75 Ω variant is often used in applications related to video signals, a 93 Ω version was historically used in some data communication applications (ARCnet, IBM 3270). These versions differ in the sizes of the dielectric parts (see photos below).

Tektronix gear transitioned from UHF connectors to BNC connectors in the early to mid-1960s. For some pieces of equipment, a conversion kit was available.

Service Scope Number 23 (December 1963) explains:

Recently, Tektronix, Inc. made the decision to convert all Tektronix instruments having UHF connectors to BNC connectors and, also, that Tektronix instruments of future design will employ BNC connectors.

The decision to convert the Tektronix product line to BNC connectors was based on the following facts:

1. BNC connectors offer lower input capacitance – an extremely important consideration in some applications.
2. BNC connectors have the requirements demanded by high-frequency instruments for good performance.
3. BNC connectors require less panel space and provide more finger room. Growing panel-density problems dictate their use.
4. BNC connectors are employed by the majority of manufacturers producing instruments used in conjunction with oscilloscopes.
5. BNC connectors are quicker and easier to connect and disconnect.

Links

• BNC connector @ Wikipedia
• BNC Connector Patent

Pictures

• 

  50 Ω BNC Female

• 

  50 Ω BNC Male

• 

  50 Ω (top) vs 75 Ω (bottom) BNC plugs

• 

  Cross section of a 50 Ω (bottom) and 75 Ω (top) BNC mated pair