Buildind a ECC83/12AX7 valve tester

[Kuga]

That looks excellent with those panel meters!

What’s the difference between the points in the circuit measured by ‘HT’, ‘B+’ and ‘anode’?

This tester works same operating conditions as a valve amplifier. I use prety the same Madamp J5MK1 amplifier power suply.
HT display it's to know I have 230Vac on the socket. I use a variac but voltage may vary. HT need to be 257-259 to know I'm testing at 230Vac. B+ display voltage show valves Vcc suply. Anode display show valve working Vcc voltage. It has a switch to show anode voltage on each triode. mA analog meter show anode current on each triode. You can see I can use a DMM to get a ultra acurated readings.


Here you can see a very worn 12AX7/ECC83 valve. When a triode show less than 1mA means you have worn out valve. If anode voltage and anode current are the same on each triode you have a balanced valve.

 

[stratfordade]

Thank you and yes that looks like a very tired ECC83.