GR-874 connector

General Radio 874 (GR-874) connectors are hermaphroditic (asexual) coaxial RF connectors developed by Eduard Karplus, Harold M. Wilson and William R. Thurston at General Radio in the late 1940s, initially "for applications up to 4500 Mc" (4.5 GHz).

They first appeared in the General Radio Catalog L of 1948. The original versions were friction-supported, in 1961 a locking series was introduced.

GR-874 connectors are carefully engineered to keep a constant impedance throughout the signal path, by varying connector diameters between free-air and dielectrically supported sections. These connectors therefore exhibit very little reflection and are well suited for frequencies up to 9 GHz and pulse applications. For higher frequencies a smaller connector is required to avoid the excitation of wave guide modes.

Most GR-874 connectors came in 50 Ω impedance. Versions for 75 Ω and 125 Ω were also available using the same ground shield and housing, but different (thinner) center pin geometry. The Tektronix 519 1-GHz oscilloscope uses the 125 Ω GR-874 variant.

The regular 50 Ω version is used in the 1S1, 1S2, 3S1, 3S7, 3S76, 3T7, 4S1, 4S2, 5T1, 5T1A, 5T3, 7M11, N, S-1, S-2, 106, 109, 110, 113, 191, 261, 280, 281, 282, R293, 661, P6025, P6032, P6051, 017-0086-00, 017-0088-00, 035-5031-00, 067-506, 067-0511-00, 067-0513-00, 067-0578-99, 067-0594-00, 067-0832-01, and possibly others, as well as in many adaptors, attenuators, and terminators.

Different versions of the connector have different maximum voltage ratings; 1000 V is typical.

By the 1970s, GR-874 connectors were being supplanted by SMA connectors in test equipment, see e.g. the progression from the S-1 to the S-4 sampling heads, also motivated by the higher bandwidth requirements.

GR-874 connectors and adapters continue to be available through IET Labs, Max-Gain Systems, Pasternack and possibly others.

Links

GR-874 Section of 1973 General Radio Catalog
GR-874 information at GRWiki including detailed lists of parts and equipment
GR connector @ Wikipedia
US Patent #2,548,457A, Coaxial connector for high-frequency transmission lines. Filed 10 Jan 1947, granted 10 Apr 1951.
MGS sales list of GR874 hardware
017-051/017-052/017-053/017-055 adapters
GR-874 Connector @ YouTube

Documents Referencing GR-874 connector

Document	Class	Title	Authors	Year	Links
GenRad Experimenter Oct 1948.pdf	Article	A Radically New Coaxial Connector for the Laboratory		1948	GR-874 connector
GenRad Experimenter Oct 1961.pdf	Article	New and Improved Coaxial Connectors		1961	GR-874 connector