Salvaged from a "grand-daddy" valve oscilloscope - a Taylor Model 31A
Taylor Electrical Instruments were a designer & manufacturer of test equipment in England
The company was purchased by AVO in 1958 and eventually AVO (which was purchased by Metal Industries in 1959) was purchased by Thorn Industries. A lot of structural changes were occurring in the electronics industry at this time.
The equipment dates from the early 1950's! see the photograph to view this ugly beast in all its former glory.
After evaluation, I decided that full restoration of this Taylor scope was not a viable project so this is one of the parts I have removed.
Philips Miniwatt Valve
Made in Holland
Age is estimated as during the period 1953 to 1970. The equipment was manufactured in 1953 but I do not know if this tube had been replaced at some stage.
Type: 12AT7 (ECC81)
Classic input stage dual triode
Type code markings are:
△ D
T ? (rubbed off) 3
These codes are printed on the base, between the pins NOT on the main glass envelope
The world of type codes is tricky, have a look for yourself at:
http://www.audiotubes.com/mullcode.htm
The 2nd row, T does match up with Philips Eindhoven afd 22652 so that's good but the vital year (2nd character) is the one that has disappeared completely!
Visually the valve appears in great shape, some rubbing of the markings though.
Unfortunately I am now "dead in the water" regarding tube testing - my testers have all been sold and I don't have a valve amp around to use substitution as a test method.
The equipment it came from WAS working way back in the 1970's (!!!) but then it has sat in storage for years and now the electro's all dried up so I cannot fire up the gear any more - in fact I have parted it out.
So I am "quite" positive that the valve has good emission and is not noisy but I cannot check this for sure.
Make any purchase with the fact in mind that this tube is UNTESTED
