Hey, How do you test a 3A4 tube in one of these? theres nothing in the chart.

I looked in a tube substitution book, and there was no replacement for a 3A4.
Could it be the tube is newer then the tester?
You could Google "testing a 3A4 in a B&K 667", or see if there are any updated charts.
Could be it wasn't made to test one.
Contact B&K.
Hopefully someone else one here can help.