Night Vision Anyone know what these adjustments are on this tube

[GBMaryland]

Anyone know what these two potentiometers are used for on this tube?

 

[TianTian]

Hi,
For me, ABC potentiometer and gain potentiometer

 

[TheHorta]

TianTian FTW!

Usually they’re sealed with epoxy. Typically a bad idea to mess with them, but if they’re exposed, someone already has.

ETA: Likely a re-pot tube. Looks like it was professionally done.

 

[Killswitch Engage]

you can make it get jiggy with that gain pot....

 

[PlinkIt]

and see what happens