GR-874
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 (1948). The original versions were friction-supported, in Catalog Q (1961) 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 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 IET Labs, Max-Gain Systems, Pasternack and possibly others.
From Arthur E. Thiessen, A History of the General Radio Company (1965):
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.
Links
- GR-874 connector @ Wikipedia
- A Radically New Coaxial Connector for the Laboratory. General Radio Experimenter, Volume 23 No.5, October 1948
- New and Improved Coaxial Connectors. General Radio Experimenter, Volume 35 No.10, October 1961
- US Patent 2548457, Harold M Wilson, Coaxial connector for high-frequency transmission lines. Filed Jan. 10, 1947; Granted Apr. 10, 1951
- MGS sales list of GR874 hardware
Pictures
-
-
-
125 Ω GR-874 connector
-
50 Ω vs 75 Ω GR-874 connectors
-
GR-874 connectors on a Tektronix 106 Pulse Generator (1966)
-
Drawings from US Patent 2548457
GR-874 Series Coax Components
| Product | Description | Introduced In |
|---|---|---|
| 874-B | Coaxial connector | 1948 |
| 874-C | Cable Connector | 1948 |
| 874-P | Panel Connector | 1948 |
| 874-PC | 874-PC panel connector and cap | 1948 |
| 874-Q2 | 874 to binding post adapter | 1948 |
| 874-Q7 | 874 to 774 coax adapter | 1948 |
| 874-C8 | Cable Connector | 1951 |
| 874-D20 | Adjustable Stub | 1951 |
| 874-EL | Coax right angle adapter | 1951 |
| 874-G10 | 3.16× coax attenuator | 1951 |
| 874-G20 | 10× coax attenuator | 1951 |
| 874-GA | Adjustable Attenuator | 1951 |
| 874-JR | Coax rotary joint | 1951 |
| 874-K | Coaxial coupling capacitor | 1951 |
| 874-L10 | 10cm airline | 1951 |
| 874-L20 | 20cm airline | 1951 |
| 874-L30 | 30cm airline | 1951 |
| 874-MR | Mixer Rectifier | 1951 |
| 874-T | 874 coax tee | 1951 |
| 874-VR | Voltmeter rectifier | 1951 |
| 874-WM | 874 50 Ω terminator | 1951 |
| 874-WN | 874 short-circuit termination | 1951 |
| 874-WO | 874 open-circuit termination | 1951 |
| 874-P58 | Panel Connector | 1954 |
| 874-P8 | Panel Connector | 1954 |
| 874-QBJ | 874 to BNC jack adapter | 1954 |
| 874-QBP | 874 to BNC plug adapter | 1954 |
| 874-QCJ | 874 to C jack coax adapter | 1954 |
| 874-QCP | 874 to C plug coax adapter | 1954 |
| 874-QHJ | 874 to HN jack coax adapter | 1954 |
| 874-QHP | 874 to HN plug coax adapter | 1954 |
| 874-QNJ | 874 to N jack coax adapter | 1954 |
| 874-QNP | 874 to N plug coax adapter | 1954 |
| 874-QUJ | 874 to UHF jack adapter | 1954 |
| 874-QUP | 874 to UHF plug adapter | 1954 |
| 874-VC | Variable Capacitor | 1954 |
| 874-X | Coax insertion unit | 1954 |
| 874-G3 | 1.4× coax attenuator | 1956 |
| 874-G6 | 2× coax attenuator | 1956 |
| 874-LBA | Slotted Line | 1956 |
| 874-LV | Micrometer Vernier Attachment for Slotted Line | 1956 |
| 874-QLJ | 874 to HL (LC) jack coax adapter | 1956 |
| 874-QLP | 874 to HL (LC) plug coax adapter | 1956 |
| 874-VQ | Voltmeter detector | 1956 |
| 874-W100 | 874 100 Ω coax standard | 1956 |
| 1607-P2 | Coax tee | 1959 |
| 874-QTNJ | 874 to TNC jack coax adapter | 1959 |
| 874-QTNP | 874 to TNC plug coax adapter | 1959 |
| 874-L10L | 10cm airline | 1961 |
| 874-QBJL | 874 to BNC jack adapter | 1961 |
| 874-QUJL | 874 to UHF jack adapter | 1961 |
| 874-TO58 | Crimping Tool | 1961 |
| 874-TO8 | Crimping Tool | 1961 |
| 874-TOK | Tool Kit | 1961 |
| 874-C8A | Cable Connector | 1963 |
| 874-G10L | 3.16× coax attenuator | 1963 |
| 874-G6L | 2× coax attenuator | 1963 |
| 874-L20L | 20cm airline | 1963 |
| 874-L30L | 30cm airline | 1963 |
| 874-M | Coax component mount | 1963 |
| 874-ML | Coax locking component mount | 1963 |
| 874-MRL | Mixer Rectifier Locking | 1963 |
| 874-R20LA | Patch Cord | 1963 |
| 874-R22LA | Patch Cord | 1963 |
| 874-TL | 874 coax tee | 1963 |
| 874-VQL | Voltmeter detector | 1963 |
| 874-QMMJ | 874 to SMA jack coax adapter | 1965 |
| 874-QMMP | 874 to SMA plug coax adapter | 1965 |
| 874-TPD | Resistive power divider | 1965 |
| 874-TPDL | Resistive power divider | 1965 |
| 874-U | Coax right angle adapter | 1965 |
| 874-W50B | 874 50 Ω terminator | 1965 |
| 874-W50BL | 874 50 Ω terminator | 1965 |
| 874-G14 | 5× coax attenuator | 1968 |
| 874-G14L | 5× coax attenuator | 1968 |
| 874-QUPL | 874 to UHF plug adapter | ? |