874-X

The General Radio 874-X is an "insertion unit" that allows custom parts or circuits to be built into it.

General Radio 1650-A

Coax insertion unit

Available from 1954 to 1978+

Manuals

Catalog History

Document	Year	Page
Catalog N	1954	139
Catalog O	1956	59
Catalog P	1959	55
Catalog Q	1961	43
Catalog R	1963	72
Catalog S	1965	92
Catalog T	1968	144
Catalog U	1970	159
Catalog73	1973	250
Catalog78	1978	101

(All manuals in PDF format unless noted otherwise)

From the 1965 catalog:

A hollow cylinder fitted with a GR874 Connector at each end and with a sleeve that slides back to provide access to a space about 2 inches long and 9/16 inch in diameter. In this space can be mounted arrangements of small components such as resistors, capacitors, or inductors. The insertion unit can be used as a shielded housing for impedance-matching networks, attenuator pads, VHF transformers, filters, and many other networks. It offers excellent shielding, minimal discontinuity in the line, and convenience.

Photos

1001-A Signal Generator Insertion Units