Home-made Valve tester

[pwdrive]

Yes it can but lots of settings in the Avo Valve Data Manual give the Vg2 setting the same as the Va setting.

Lawrence.

[Sparks]

The battery bias is easy enough, I may even put a lid switch on the box to automatically switch it off when the lid is closed.
Don't really want to get involved with zeners, as I don't really know how to deal with them, and only have vague ideas of what they do!
Bob

[pwdrive]

A zener diode would be optional, if the mains voltage into the transformer is reasonably stable then no real need for one.

Lawrence.

[Sparks]

I did consider putting a mains PSU inside it for the variable screen voltage, but decided against it in favour of a variable supply of 0 - 250 Volts DC going into the unit, the anode voltage being selected from the variac, and using the same voltage with the coarse and fine screen dropper from the same supply. A 12 variable 12 Volt battery grid bias appeals to me mainly because of its simplicity. A battery, switch and pot. cost less than a pot, transformer, rectifier and smoothing! I do have all those items, but putting a 12V transformer in it would be one less transformer for other projects!
I will be starting by building the box first of all!
Bob