[Milsurplus] Any idea what this is?

[Email4KH at aol.com]

This flush mount meter has a 2" diameter round white face.  The sole gauge is 
labeled "Antenna Position Degrees" with ticked range of -2.5 thru +2.5 on the 
top, and "Received Signal Level" with range of 0-100 on the bottom.  Needle 
is anchored at 6 o'clock. Additional text on the face reads "ES=50 UADC"  and 
"621-19230" (mfr. part number, I suppose).  I know the description is 
confusing, but if these labels and ranges make any sense to you, and you know what this 
thing is, please reply.  I'd be glad to send photos.