Hi,

I still have the meter I rescued from the 19 set I bought in the 1950s - there is a marking in the lower left "F. G. X4".

Does anyone know what this means?

73

Jim - G3ZQC

Do you own a serviceable 19 Set? No

I do not know, however I have a No. 19 set that I have fitted a
different meter to and if you are interested in selling that meter
I would very much like to have an original.

Do you own a serviceable 19 Set? no

The "F.G. X4" relates to British Standard 89 for direct-reading electrical instruments. The classes were Sub Standard, First Grade, Second Grade (and possibly even Third Grade), indicated by a two letter abbreviation. Sub Standard (S.S.) meant calibrated directly against the laboratory standard for the unit, First Grade (F.G.) was the next level down, Second Grade (S.G.) was 'Indication only', and Third Grade (if it existed was: "well, there's something there (or not)").

During WW2 materials shortages led to a relaxation of standards, and I think that was what the 'X' implied. (At one point there was a shortage of jewels for watches and meter movements and metallic bearings were used instead - they were very definitely not accurate.)

Post-WW2 the classifications were changed: Sub Standard (S.S.) became 'Precision' (Pr.), First Grade (F.G.) became 'Industrial' (In.), and I think they dropped anything lower than that altogether.

(I actually went and researched this in the British Standards Institute library, but the wartime amendments were incomplete and I never did discover what the X4 actually meant.)

Best regards,
Chris.(G8KGS)

Do you own a serviceable 19 Set? Yes.

Hi Chris,

Thank you for your response. Really surprised to see any reply after such a long time. I can't remember what research I did at the time, but obviously wasn't looking in the right place. So it looks as though the X4 will remain a mystery.

Thanks again.

Regards

Jim - G3ZQC

Do you own a serviceable 19 Set? No

Glad to see
Some life on this website. Too bad it is so quiet. 73