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| | Mullard, Philips, and Valvo Tube Codes |
 | | MostAmperex, Mullard, Philips and Valvo tubes are marked with a group of symbols which contain coded information relating to the type, place of manufacture or country of origin, and the date of manufacture. |
 | | There are some deviations to this rule, and in certain manufacturing plants not all of the code protocol was followed exactly, with every batch of tubes. |
 | | Prior to 1955, Mullard used a purely numerical code for encoding the tube type, but then adopted the code change as listed here after that. |
| www.audiotubes.com /mullcode.htm (1256 words) |
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