12AX7 With no Glow?

[Platefire]

I got a brand new EH 12AX7 that has no heater glow? It works and both stages test about 40 on my TV-7A/U tube tester with minimum being 25. So it's apparetnly strong! I never recall having one that didn't glow---is this normal? Platefire 

[eleventeen]

Some 12A_7, the ends of the heaters are recessed inside the teensy tubes that form the cathodes and you can barely see anything...if there is getter flash on the top of the tube it's almost impossible to see even a pinprick of light when they are on. After a few minutes they get warm to the touch, that's the only indication of them being powered on.

Some 12A_7 like a Telefunken I have from a hp power supply flash brightly and look like they are going to explode when they are turned on. Then they look normalish after the blast wave goes by.

[Platefire]

OK Thanks! Thats good to know. Yes I have some Heathkit/Mullards that flash like that in my Silvertone 1482. I thought they were about to kick the bucket, but after a while realized thats standard fare! Platefire