Testing 2A3 tubes

[Aural Robert]

So I went to my local audio store this afternoon to test my 2A3 tubes as I suspect one of them has weakened. The testing machine is older, I don't know maybe 40 years? It has a flip chart of tube types to set the various dials and thingies on the device itself to ensure you don't cook the filaments etc. The 2A3 doesn't show up on their list. The shop owner did some poking around and said a 2A3 is a 300B, but no listing for 300B either on the flip charts.

Are there any other tube numbers the 2A3 might be known by? The machine did have the correct socket, I had my tube plugged into it. We didn't power up of course.

I figured if anyone knows it's the designers of the circuit. TIA all.

Aural Robert
... Get out of the road if you want to grow old ...

[fullheadofnothing]

Ummm, a 2A3 isn't a 300B. I dunno if I'd trust someone that made that assumption to test any tubes I valued. Does the tube tester have a 4-pin socket?

[Doc B.]

Setting a tube tester up for testing a 300B and plugging a 2A3 in could kill the 2A3. Don't use a tester without the proper calibration chart.

You can test the tube in the amp. Just measure the voltages. If the cathode voltage of the 2A3 is low the tube is aging.