The simplest vacuum tubes resemble incandescent light bulbs in that they have a filament sealed in a glass envelope which has been evacuated of all air.When hot, the filament releases electrons into the vacuum: a process called thermionic emission. For most purposes, the vacuum tube has been replaced by the much smaller and less expensive transistor, either as a discrete device or in an integrated circuit. and Canadian English) or (thermionic) valve (outside North America) is a device generally used to amplify, or otherwise modify, a signal by controlling the movement of electrons in an evacuated space.Instead, there were approximately 2000 of these chasses produced, which then ended up as one of the three models in question.
Thus as an example 606452 is a transformer code: 606 tells us it is a Schumacher transformer made in either 1964 or 1974 and and it was built on the last week of December.
If the transformer was read from a silverface Vibro Champ we can deduce it was made in 1974 – almost…
Remember that this is when the transformer was manufactured.
They are all very rare today and few have survived.
The first amplifiers made in-house by Fender is the Woodie series, built in 1946 through 1948.