13-01-2020, 01:10 PM
You can also measure filament / heater resistance. In general when cold about half what the voltage & current suggests. You can compare with known valves of the same type.
Some valves (Mullard / Philips) have a separate etched part code. Different factories may have a different code. Apart from dismantling and measuring every part, and testing at same rating, this is also how we know that ECH81 = ECH83, just a different datasheet and part number. Absolutely proven to be same valve.
Some valves (Mullard / Philips) have a separate etched part code. Different factories may have a different code. Apart from dismantling and measuring every part, and testing at same rating, this is also how we know that ECH81 = ECH83, just a different datasheet and part number. Absolutely proven to be same valve.
