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| [[File:GR-874 connector 1.jpg|250px|thumb|right]] | | #redirect [[GR-874]] |
| '''General Radio 874 (GR-874)''' connectors are hermaphroditic (asexual) coaxial RF connectors developed by [[Eduard Karplus]], [[Harold Wilson]] and others in the late 1940s, initially for applications up to "4500 Mc" (4.5 GHz).
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| 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.
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| 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. See for example the [[tekwiki:519|Tektronix 519 oscilloscope]] that had a 125 Ω GR-874 variant at the input.
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| Different versions of the connector have different maximum voltage ratings; 1000 V is typical. There are locking and non-locking versions.
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| By the 1970s, GR-874 connectors were being supplanted by SMA connectors in test equipment, also motivated by increasing bandwidth requirements.
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| GR-874 connectors and adapters continue to be available through [http://www.ietlabs.com/gr874-connectors.html IET Labs], [http://www.mgs4u.com/RF-Microwave/General-Radio-GR-874.htm Max-Gain Systems], [https://www.pasternack.com/gr874-adapters-category.aspx Pasternack] and possibly others.
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| The connector was also used by other manufacturers in the 1960s and 1970s, e.g. Tektronix (see [[tekwiki:GR-874 connector]]), Hewlett-Packard, and Philips.
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| ==Links==
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| * [[wikipedia:GR_connector|GR connector]] @ Wikipedia
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| * [https://archive.org/details/sim_general-radio-experimenter_1948-10_23_5 A Radically New Coaxial Connector for the Laboratory. General Radio Experimenter, Volume 23 No.5, October 1948]
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| * [https://archive.org/details/General_Radio_Experimenter_1961_10 New and Improved Coaxial Connectors. General Radio Experimenter, Volume 35 No.10, October 1961]
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| * [[Media:GR874 1973 GR Catalog.pdf | GR-874 Section of 1973 General Radio Catalog]]
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| * [https://patents.google.com/patent/US2548457A/en US Patent 2548457, Harold M Wilson, ''Coaxial connector for high-frequency transmission lines'']. Filed Jan. 10, 1947; Granted Apr. 10, 1951
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| * [http://www.mgs4u.com/RF-Microwave/General-Radio-GR-874.htm MGS sales list of GR874 hardware]
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| ==Pictures==
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| <gallery>
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| GR-874 connector 1.jpg
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| GR-874 connector 2.jpg
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| GR-874 connector 125 Ohms.jpg | 125 Ω GR-874 connector
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| US Patent 2548457.jpg | Drawings from US Patent 2548457
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| </gallery>
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| [[Category:Introduced in 1948]]
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