DBT brightness - refresher needed

[62vauxhall]

It's been a while since I've used it, and I can't remember how "illuminated" a DBT should be if all is well.

I have something plugged into one that lights the lamp brightly on initial turn on then goes to about half intensity after the initial surge. Isn't there supposed to be a barely perceptible glow or no glow at all?

I could not find anything definitive online but mention was made of different amp types inducing different brightness levels from a DBT.

 

[NavLinear]

The dim bulb tester should illuminate brightly when you first apply power but should dim after the power surge. The amount of illumination after the surge is dependent upon the unit under test and the wattage of the incandescent bulb.