Joe:3119 wrote: heater volts are 2V so it wouldn't be any good for 1.5V battery valves.
Not true, I have this model of tester, the heater extension unit allows you to select multiple heaters ranges by switching between the main panel and the extn unit giving you a range between 1.1V to 117V for heaters. Quite a good little tester, for testing gm and emission (bad/indiff/good)
I have tested battery valves, as well as some TV valves with honking great heater voltages.
My tester shown in post #2 http://vintagetvandradio.myfreeforum.org/about435.html