Radio Operator, Low Speed - SSN 776 - Marines

The Marine Corps Specification Serial Number (SSN) 776 meant Radio Operator, Low Speed. Does the Low Speed refer to the operator or the radio equipment? If the former, how slow? If the equipment, do you know of a manual or anything that describes the equipment?

My father was a Radio Operator, SSN 776 and I'm trying to figure out what type of equipment he may have used.

Thanks for any tips!

 

RADIO OPERATOR, LOW SPEED (776)

Installs and operates tactical field radio transmitting and receiving equipment. Sends and receives messages by International Morse Code (CW, ICW, or tone) signals and by light signals. Normally operates in radio nets below the level of a division.

Receives CW, ICW, or tone signals and prints pencil copy at minimum speed of 13 five-letter random code groups per minute without error for a minimum period of 3 consecutive minutes out of 5.

Transmits CW, ICW, or tone signals, using hand key, at a minimum speed of 13 five-letter random code groups per minute Without error for a minimum period of 2 consecutive minutes out of 3. Handles, without error, a minimum of 12 plain-dress normal form messages (averaging 10 five-letter random code groups of text) per hour in a field radio net of two or more stations through natural interference.

Receives and transmits messages by light signals at a minimum speed of 5 words per minute. Maintains records pertaining to the handling of messages.

Performs First echelon maintenance by keeping equipment clean, inspecting cords, plugs, antenna mast, receiver, transmitter, and calibration charts, making minor repairs or adjustments, such as changing tubes, adjusting frequencies, and adjusting key, using small hand tools.

Must possess a working knowledge of combined Radiotelephone and radiotelegraph and authentication procedures. May be required to encipher and decipher messages using Converter M209.
RADIO OPERATOR, LOW SPEED (776)