US Navy Keys
US Navy High Speed Morse Code Certificate Requirements: Send & Receive CW at 30wpm. This probally is among the last certificates issued. In the late 6Ø's CW had all but been replaced by on-line crypto equipment for both RTTY and Voice operations. In the 7Ø's the Navy suspended teaching Morse Code at The Radioman "A" School. Greg also received a Vibroplex with the certificate Royal Navy ARS morse code Certificate of Proficiency Navy MARS Call - NØZMC Once I Was a Navyman

Manufacturers Codes - 1915 to early 193Øs Listings from http://www.metronet.com/~nmcewen/Navy_numbers.html
CA	American Radio Research Corp.	CAB	Baldwin Telephone Co.
CAC	Central Telephone Co.	CAD	Domestic Manufacturing Engineering Co.
CAE	Cutler Hammer Manufacturing Co.	CAF	John Firth
CAG	General Radio	CAH	Cutter Manufacturing Co.
CAJ	Holtzer Manufacturing Co.	CAK	William J. Murdock
CAL	Locke Insulator Co.	CAM	Manhattan Electrical Supply Co.
CAN	Sagame Electric Co.	CAO	Ward Leonard Co.
CAP	Frank B. Perry	CAQ	Robbins and Meyers
CAR	Roller Smith	CAS	Chloride of Silver Co.
CAT	American Transformer Co.	CAU	Triumph Electric Co.
CAW	C. & C. Electric Co.	CAX	Metropolitan Electric Co.
CAV	Industrial Controller Co.	CAY	West Electric Controller Co
CB	Crocker Wheeler Co.	CD	E.J. Simon
CF	DeForest Radio Telephone & Telegraph Co.	CG	General Electric Co.
CH	Electrose Insulator Co.	CK	Kilbourne and Clark
CL	Fritz Lowenstein	CM	Marconi Wireless Telegraph Co. of America
CN	National Electric Supply Co	CO	Copely Manufacturing Co.
CP	Cutting and Washington	CQ	International Radio Telegraph Co.
CR	Wireless Specialty Apparatus Co.	CS	Sperry Manufacturing Co.
CT	Federal Telegraph Co.	CU	Miller Resse Hutchinson
CV	Weston Instrument Co.	CW	Western Electric Co.
CY	Wireless Improvement Co.	SE	Bureau of Steam Engineering, US Navy
Key Designations - XXX-26ØNN - early 193Øs to post W.W.II
CABH	Signal Electronic & Mfg. Co.	CABJ	Lionel Corp.
CAKU	Winslow Co.	CAPH	Telegraph Apparatus Co. (Ted McElroy)
CAPZ	Telegraph Apparatus Co. (Ted McElroy)	CAQZ	Brelco
CAY	Westinghouse Electric & Mfg. Co.	CAZ	Brooklyn Metal Stamping Co.
CAZT	Electro Specialty Co.	CBBX	Western Union Telegraph Co.
CDM	D.P. Mossman Co.	CEA	Bendix
CEJ	E.F. Johnson	CHD	Hardwick-Hindle, Inc.
CJB	J.H. Bunnell	CJF	J.F. Frietz
CJY	Leach Brothers	CKI	Chicago Apparatus Co.
CLR	Leach Relay	CLS	L.S. Brach
CLT	Lundquist Tool & Mfg. Co.	CMH	American Radio Hardware
CMI	The Molded Insulator Company	CMK	McElroy Electronics (Ted McElroy)
CN	National Electric Machine Shops Inc.	COL	Collins Radio Co. Inc.
CRR	Bendix	CRV	RCA Victor, Div of RCA
CSE	Signal Electric	CTC	Chicago Telephone Supply
CTE	Telephonics Corp.	CUZ	United States Telev. Mfg. Co.