The Lynch AZ-31 Speech Scrambler was part of the Lynch E7 system, and was made in the early 1950's

This rack mount unit used vacuum tubes, worked with an oscillator and generated 233 useful scramble patterns (set by the knobs on the panel) out of a possible 16,000. The device was not government classified, even in 1954 since it only provided medium security. Not even the manual has a security classification so it's assumed this device was used in commercial service.

Weight: Over 50 pounds.

The front panel of the AZ-31 with the hinged cover swung down. It's not too often that equipment such as this is still seen in the original shipping box.