Reed-Contact Switch Series for the I. F. Band

The nationwide network of transmission facilities is not only growing in number of routes and capacity but also in terms of service capability and administrative flexibility. Within the network there are usually alternate routes for providing service between two points. Interconnection between points may ultimately be controlled by a remote, centralized, real time machine that contains an accurate map of the state of the network. The broadband restoration system, for example, can detect failures, make routine maintenance checks and report to a regional control center where an alternate route between the two points is selected. The control center then remotely operates the wideband switch at each junction of the route to effect a restoration of service. One component group needed to implement these systems is a family of wideband switches capable of meeting the transmission requirements of low insertion loss, high isolation loss, high crosstalk loss, and having an impedance well matched to the 75-ohm system impedance. The 266B ( 8 X 8 matrix), 274A ( 1 X 8 ) , and 273B (1 X 2) switches have been developed to meet these requirements with low operate power, small size, and moderate cost. All of these codes use 237-type miniature dry-reed sealed contacts in a cable-switch1 arrangement to provide an extremely high isolation loss in the open state and a low insertion loss and good impedance match in the closed state. Appropriate matrix configurations are achieved by interconnecting the cable switches with 229