Electronic Valve Manufacturers' Factory Identification Code

CV marked valves usually carry a code to indicate the manufacturer and where the pumping process was completed. The following table lists these codes:

Code Manufacturer Factory
A Mullard Radio Valve Co., Blackburn (prior to January 1951)
A Thorn Tottenham (prior to April 1964)
AB Sylvania-Thorn Enfield
AC Thorn-AEI Footscray
AD Thorn-AEI (Brimar) Rochester
B Edison Swan Baldock (prior to September 1945)
BA AEI (Asssociated Electrical Industries Ltd.,) Woolwich
BC Joseph Lucas Birmingham
C Edison Swan Ponders End (prior to September 1951)
CC Cathodeon Cambridge
CE 20th Century Electronics New Addington (prior to March 1957)
CF 20th Century Electronics New Addington
CN Pye Industrial Electronics  
CO Newmarket Transistors Newmarket
CS Cathodeon Southend
D Mullard Radio Valve Co., Micham
DA Mullard Radio Valve Co., Blackburn
DB Mullard Radio Valve Co., Salford
DC Mullard Radio Valve Co., Whyteleafe
DE Mullard Radio Valve Co., Fleetwood
DF Mullard Radio Valve Co., Waddon
DG Associated Semiconductor Manufacturers Southampton
DH Societe Anonyme Philips Brive, France
E Thorn-AEI Brimsdown
EA Edison Swan Ponders End
EB Edison Swan Gateshead
EC Edison Swan Tottenham
EN Thorn-AEI Sunderland
F STC (Standard Telephone and Cable Co.,) Paignton
FB STC (Standard Telephone and Cable Co.,) Footscray
FC STC (Standard Telephone and Cable Co.,) -Lorenz Esslingen, Germany
FD STC (Standard Telephone and Cable Co.,) Rochester
FE STC (Standard Telephone and Cable Co.,) Oldway (additional to Paignton Factory 'F')
FF STC (Standard Telephone and Cable Co.,) Harlow
G Ericsson Beeston
GA AB Svenska Elektronror (Ericsson) Stockholm, Sweden
H Hivac Harrow
HC Hivac Chesham
HR Hivac Ruislip
J STC (Standard Telephone and Cable Co.,) Crewkerne (prior to January 1946)
J Radar Electronic Equipment  
JA SGS Fairchild Ruislip
JB SGS Fairchild Agrate, Milan, Italy
JD Elliott Bros. (London) Ltd., Borehamwood
JE Elliott-Litton Borehamwood
JK La Radio Technique Suresne, Paris, France
JN International Rectifier Co., (GB) Ltd., Oxted
JQ Associated Transistors Ruislip
JT Microwave Associates Ltd., Luton
K Electronic Tubes High Wycombe
L CSF (Compagnie G ale de T.S.F.) Levallois-Perret (Seine), Paris, France
L MO Valve Co., (prior to Oct. 1951)
LB CSF St., Egreve, Grenoble, Lsere, France
M Gramophone Co., Hayes
MA EMI Research Labs., Hayes
MB EMI Research Labs., Ruislip
MB EMI Hayes
MR EMI (Valve Division) Ruislip
MT EMI Treorchy
N Nore Electric Southend
N STC (Standard Telephone and Cable Co.,) Footscray (prior to August 1951)
NP Texas Instruments Dallas Road, Bedford
NQ Texas Instruments Bedford
NR Texas Instruments Nice, France
O Rank Cintel Lower Sydenham
OR Rank Cintel Rotunda
OS Rank Cintel Sidcup
P Philips Eindhoven, Holland
P GEC (General Electric Co., Ltd.,) Shaw (prior to August 1951)
PA Philips Teleindustri Stockholm, Sweden
PDA Philips Hendon, Australia
Q EEV (English Electric Valve Co.,) Chelmsford
QB MWT (Marconi Wireless Telegraph Co., Ltd.,) Great Baddow
QC MWT (Marconi Wireless Telegraph Co., Ltd.,) Chelmsford
QD EEV (English Electric Valve Co.,) Stafford
QE EEV (English Electric Valve Co.,) Kidsgrove
QF EEV (English Electric Valve Co., ) (Nelson Research Labs) Hixon
R Ferranti Moston
R Ferranti Gem Mill (prior to July 1947)
RA Ferranti Edinburgh
RB Ferranti Dundee
RC Ferranti Chadderton, Oldham
S AEI (Asssociated Electrical Industries Ltd.,) Rugby
SA AEI (Asssociated Electrical Industries Ltd.,) Lutterworth
SB AEI (Asssociated Electrical Industries Ltd.,) Lincoln
SC CFTH Usine de Joinville, Seine, France
SD SESCO Rue de L'Amiral, Mouchex, Paris, France
SDA AWV (Amalgamated Wireless Valve Co., Pty Ltd.,) Sydney, Australia
SF CFTH Rue Mario-Nikis, Paris, France
SL AEI (Asssociated Electrical Industries Ltd.,) Leicester
SP AEI (Asssociated Electrical Industries Ltd.,) Peterborough
T British Tungsram Tottenham
U MO Valve Co., (prior to October 1945)
U Nucleonic and Radiological Strafford
V Cossor Highbury (prior to September 1945)
V Gilbert Photelectrics  
VA Westinghouse Chippenham
VF MCP Electronics Alperton
VL Hughes Internations (UK) Ltd., Glenrothes
VR Brucsh Crystal Co., Hythe
W GEC (General Electric Co., Ltd.,), Hirst Labs Wembley
WB GEC (General Electric Co., Ltd.,) Coventry
WD Claude General Neon Lights Wembley
WE ASM Ltd., Hazel Grove
WF ASM Ltd., Broadstone
X MO Valve Co., Springvale (prior to October 1951)
Y MO Valve Co., Moray (prior to April 1945)
YA Leigh Electronics Havant
YC Semiconductors Ltd., Cheney Manor, Sweden
YD Semiconductors Ltd., Towcester
Z MO Valve Co., Hammersmith
ZA MO Valve Co., Gateshead (prior to March 1957)
ZB MO Valve Co., Perivale
ZC MO Valve Co., Springvale (prior to August 1957)
ZD MO Valve Co., Dover (prior to December 1956)
ZE Osram GEC Lamp Works MXT Dept (prior to March 1957)


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