I got this from a buddy til the one I ordered comes in. This is an old civil defense P.O.S

I got the power on and got it zero.

I am not reading anything, and was wondering if anyone knows these old units. I have no idea how to calibrate it or check to see if its acurate.

Just something to mess with til mine comes in. My buddy knows nothing about this model, just got it off ebay while back.

Any help or knowledge wanted.

Thanks in advance