Using a 25 cycle AC meter on 60 cycle current....

[Kamakiri]

I was at an estate sale this morning, and saw a bunch of antique meters there. I wanted one for my variac, as it just has a dial, and I came across this monster. It's identical to the one in the pic, except that it's a "B" and not a "C" style. It weighs about 10 pounds!

Tried it out on AC line current to see that it pegged as soon as it made contact. Then, I realized that THIS one is made for 25 cycle current as opposed to 60 cycle (the pic isn't the meter I have, but other than that is identical).

Question is, can I use this thing on 60 cycle current, and if so, what modifications do I need to make to the line voltage going in?