View source for GR-874

[[File:GR-874-C8A.jpg|250px|thumb|right]]
{{Title|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 {{Catalog L}}. The original versions were friction-supported, in {{Catalog Q}} a locking series was introduced.

GR-874 connectors are carefully engineered to keep a constant impedance throughout the signal path, by varying conductor 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.

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

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 [[tekwiki:519|Tektronix 519 1-GHz Oscilloscope]] uses a 125 Ω GR-874 variant.

Many GR instruments came with GR-874 connectors standard.  A large variety of adapters to other coax connector standards was available that allowed the end user to configure their instruments according to their interconnection needs. 

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.

From Arthur E. Thiessen, ''[https://www.cs.cmu.edu/afs/cs/Web/People/ram/electro/gr/history.pdf A History of the General Radio Company (1965)]'':
<blockquote>
Also, in 1948, after field tests and demonstrations lasting two years, the unique Type 874 coaxial connectors were announced. 
These were a joint development by Karplus, Harold M. Wilson (M. I. T. '31), and William R. Thurston (M. I. T. '43).
A feature of the unique design is that any two connectors fit smoothly together without the usual complication of matching male and female assemblies. 
This feature, together with excellent electrical and mechanical performance, made them an immediate success. 
It is not known exactly how many of them are in use today in all their forms, but the number is in the millions.
</blockquote>

==Links==
* [[wikipedia:GR connector|GR-874 connector]] @ Wikipedia
* [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]
* [https://archive.org/details/General_Radio_Experimenter_1961_10 New and Improved Coaxial Connectors. General Radio Experimenter, Volume 35 No.10, October 1961]
* [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
* [http://www.mgs4u.com/RF-Microwave/General-Radio-GR-874.htm MGS sales list of GR874 hardware]

==Pictures==
<gallery>
GR-874 connector 1.jpg
GR-874 connector 2.jpg
GR-874 connector 125 Ohms.jpg  | 125 Ω GR-874 connector
GR-874-50 ohms vs 75 ohms.jpg  | 50 Ω vs 75 Ω GR-874 connectors
Tek106-outputs.jpg             | GR-874 connectors on a [[tekwiki:106|Tektronix 106 Pulse Generator (1966)]]
US Patent 2548457.jpg          | Drawings from US Patent 2548457
</gallery>

==GR-874 Series Coax Components==
<small>
{{#cargo_query:
tables=Products
|fields=_pageName=Product,Description=Description,Introduced=Introduced In
|where=Series='GR-874'
|order by=Introduced In,Product
|limit=500
|offset=0
}}
</small>

[[Category:Coaxial Elements]]
[[Category:Introduced in 1948]]