It sounded subversive, a peek behind a curtain of some kind. So I ferreted it home, and over many days, scanned it one page at a time into a PDF. It was the 1940 edition, so I have no doubt that in fact enlisted men can freely read this completely out of date 69 -year-old radio navigation text.
"CAUTION! NOT TO BE ENTRUSTED TO THE CARE OF ENLISTED MEN!"
Radioman 2c is a designation under the artificer's branch. It that sets pay grade, an insignia, and indicates a set of positions that person may hold. Like most military positions to move up in rank one must pass a test. This is the instructors exam with answers for the Radioman 2c exam. There's a little more information here.
Radioman was a rating for United States Navy and United States Coast Guard enlisted personnel, specializing in communications technology. The rating was created in 1921 and was used continually until it was merged with Data Processing Technician into the Information Systems Technician. The Radioman was not just a DJ, what they called a Broadcast Operator, but also teletype repairmen, Crypto operators, supervisors, Distro Operators and every other job that fell under the qualification.
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