Hoyt Radio Rotary Meter - How to test this portable multimeter?

[ez24]

I have one of these:

http://www.radiomuseum.org/r/hoyt_radio_rotary_meter.html


and was wondering what it was for?  I guess used on radios?  The meter rotates, thus the name rotary.  Looking at the main picture, it has three posts on the left and three on the right.

The upper large left one is marked " 30 AMPS " on the left side.  The smaller middle post reads " 3 AMPS "  and the lower small one reads " 30 MIL-V "

The upper large right post reads " + ", the smaller middle one reads " 3 VOLTS ", the lower small right one reads " 30 VOLTS"

Summary of readings (for posts):

30 AMPS          +                 (big posts)
3   AMPS          3 VOLTS       (small posts)
30 MIL_V         30 VOLTS     (small posts)

I want to test this but I do not want to do something stupid.  What throws me is the " + " sign.

I have a bench ps that I can control the amps and volts but not near 30 amps.  Could I hook up the positive terminal from the power supply to " + " and negative to "3 volts" and turn up the volts to 3 and see what happens.  The same for 30 volts

Can I assume " 30 MIL_V"  is 30 millivolts ?

Hook up the ps and turn up the amps and volts to test amps ? 

Any ideas on how to test this mulitimeter?

thanks

[radhaz]

Did you see this?
https://books.google.com/books?id=PNgDAAAAMBAJ&pg=PA664&lpg=PA664&dq=Radio+Rotary+Meter&source=bl&ots=t_h0-w2GWz&sig=bmfVukWP56I4BSKf_D5los9CfO8&hl=en&sa=X&ei=6yWQVf3ZMcTZoASi-oX4DA&ved=0CDIQ6AEwAw#v=onepage&q=Radio%20Rotary%20Meter&f=false

[ez24]

Thanks

I did not know that the meter had to be rotated.  I thought it was for how it was to be held, it must of had a pointer that is missing.  I tried it at 3 and 30 volts and it works and is accurate 
Strange to hook up a positive lead and move the negative.

Probably designed to be hooked up with several wires at the same time and the dial rotated to the different readings.  Wished I had a 1926 radio to use it on.

Hard to stop reading the Popular Mechanics, I miss those old magazines.