I have some info from sowter about:
"This was built to customer specification for which we have the following brief:
10k/10k
For use with a source of 100 ohms
Turns ratio 1:1.3
Max level +24dBm at 40Hz"
Colours:
_______ ||| _______
PINK BROWN
)|||(
)|||(
VIOLET________)|||(_______ GREY
|||
BLACK-= SCREEN