[Boatanchors] Moving coil instrument help

[G4GJL]

Guys, can anyone help me to identify the generic type of instrument that I 
have here?

It is a 4-terminal moving coil instrument taken from a Military ATU, and was 
used for VSWR and Power Absorbtion Factor monitoring on an HF transmitter. 
Four wires connected to the RF sensing head, which I never had or even saw.

Question is....What type of instrument is it? Is it a dynamometer, like the 
"VI COS(phi)" instruments used in electrical labs, or is it something more 
subtle?

As I dont know what type of RF pickup unit was use with the instrument, I 
really cannot guess, but it seems strange that two signals could be derived 
from a pickup line which when multiplied in such an instrument, would yield 
VSWR or Power Absorbtion Factor as their product.


Any clues appreciated

Pete
G4GJL