Yellow printed Mullards

[59Vampire]

found one with blackburn code in the stash. whats the deal with the yellow:huh

[Timbre Wolf]

found one with blackburn code in the stash. whats the deal with the yellow:huh
Early '60s Mullard printed in yellow paint. Is it an "I61" type-coded tube? That's from early '60s.

- Thom

[59Vampire]

i63 what does that signify?

[Timbre Wolf]

i63 what does that signify?
That is the tube "type" code; I6 signifies an ECC83 (12AX7), in the Philips tubes manufacturing code. Check out this excellent resource (http://www.tube-classics.de/TC/Tubes/Valvo/Phlipscode.htm) for more information.

I61 was the earliest Mullard short-plate 12AX7A type, and I63 was the later one (starting in mid-'60s). Dutch Amperex or Miniwatt, German Siemens or Valvo, and others used the same type codes, since they were part of the Philips conglomerate. But each had its own manufacturer code that was unique.

- T

[59Vampire]

thanks!