This is one of a number of instruments
given to me by Martin Harrison
which belonged to his father who was a a Chartered Electrical Engineer.
He collected both old electrical test equipment and due to his name
(John Harrison) old clocks. Martin thought his father would have been
pleased with his items new home and owner.
I have given it a clean and found to work
very well. I
checked the meter against one of my digital meters and found it to be
accurate. I guess that F.G.
indicates that it is a First Grade instrument to the British Standard.
The model number AP1806 may indicate that it was made for the Air
Ministry. It requires 5mA for full scale deflection.