How to identify unmarked vacuum tubes (European)

If you pick up batches of used vacuum tubes from time to time, you probably end up with quite a collection of vacuum tubes with unreadable or missing markings. Over time I've developed some methods to identify these tubes with a fairly high success rate.
Note: I mainly focus on European tubes in this video

00:00 Introduction
03:08 Using the type code
21:40 Identifying internal tube elements
33:15 Identifying the heater
42:51 Exhaustive example of identifying a tube
1:05:02 Outro

Philips-Mullard Factory Valve Codes: https://frank.pocnet.net/other/Philip...


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