Weston 525 : The 'Klaatu' Meter (Ebay purchase for the QTS collection received August 10, 2005)
I'd call this the 'top' side. I'd never seen one until there was a reported sighting on Rec.Antiques.Radio+Phono. Here's what I (think I) know thus far:
IMO definitely a 'schoo/lab' demonstration meter. No scale calibration per se, "0" at center scale, "-" and "+" at the alternate ends of scale (only.) Shown de-energized here. As received, this one had been seriously dorked with, pointer bent, hardware stripped inside, it took a while for me straighten the internals out (to where it's now smoothly operating and clean inside.) People who like leaving their fingerprints on stuff should stay out of things like this! Although the outside might look painted, it's not; the case is cast aluminum alloy that's got a sort of rough patina effect to it.
'Down' or bottom side. Thanks to someone at Rec.Antique.Radio+Phono for suggesting this might be a 'projector meter'; I agree. As shown, 'energized' to read "0" (see next paragraph below.) As original, the meter scale and the unit ID label are 'inverted' from each other (no obvious 'up' or 'down' in vertical orientation.) *If layed down flat on an overhead projector*, this side down, the meter scale/pointer will nicely display on the projector screen! In this application, the cause for the 'Klaatu' case styling becomes obvious: the aluminum finned case is one big heat sink (the top glass surface of older 'high power' overhead projectors can get fairly warm!)
(Click on image above for closeup, separate 104K .jpg load.) The inside, after I'd cleaned it up a bit. The movement has a DC resistance of 735 ohms, paralleled with a fixed resistance of 757 ohms (I think the hand written number inside the case is for the resistor calibration value.) Although the meter movement had been seriously dorked with before it got here (the pointer and rests bent, etc), all of the 'essential' bits were there. I'm 100% sure that as designed this is a 'normal' left to right movement (as opposed to having a center scale mechanical reference, i.e. for galvanometer application.) As shown, I've about 286 millivolts DC at the terminals to make it read "0" (with the armature spring set levers cranked to prevent burying the pointer at 'rest'/no signal.) If I reset the armature spring mechanical references a bit (to where they'd be closer to what would be typically 'normal' for this sort of movement), it will neatly read "0" at 1 milliamp DC. Makes me think that '1 milliamp DC' was/is the target/intended reference point for "0". Any Weston catalogs out there to confirm this (? Please let me know!)
Serial number 1043 : manufactured date of September 1951 : Hey, that's the same year "The Day The Earth Stood Still" was released, wasn't it?