What might this unit be for?

[abwdvm]

https://photos.app.goo.gl/4PF1ryqDi4UTecj53

Removed from service years ago. AM Station.

[Deep Thought]

That is almost certainly a homebrew modulation monitor.

[kkiddkkidd]

That is almost certainly a homebrew modulation monitor.

I concur...

[davek]

would the cryptic inscription on the front offer any clues?

[kkiddkkidd]

would the cryptic inscription on the front offer any clues?
clue.png

But that could just be a clever attempt to mask the real insidious use for a box with a knob, switch and a couple of meters.

You know... like a clandestine loudness control for which only the PD has the combination. Who is to say that the center zero meter isn't a listener monitor to tell the PD if more or less people approve of his loudness control knob adjustments?

[Deep Thought]

Labels are just a convenient way to containerize things we can't control.

I've seen similar things which were merely remote meters, but this one seems to be more 3D than those.

[ChuckG]

Who is to say that the center zero meter isn't a listener monitor to tell the PD if more or less people approve of his loudness control knob adjustments?

Sure, it goes up when he increases the loudness. Don't encourage him.

Incidentally years ago I had a FCC inspector give me the side-eye for having a big VU meter in the studio rack, fed by rectified off-air audio because it was labeled "modulation". He wanted to see the calibration..... Or I could take the label off.