The Astatic JT-30 microphone is the perfect Harmonica mic for use with a vintage tube amps. It was created about 70 years ago and only recently has gone out of production. This JT-30 is believed to be from the 70s or 80s and that date is based n the look of the label.

I have no way of knowing if this works or not but will be happy to take this back if found that it does not work.