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) |
・Brief Self-An Introduction to The Audiophiles
・Electron Valves and Vintage Tubes Pages
E-mail to
kouchi@cypress.ne.jp