Precision AVOmeter s/n 441-567 working
This instrument was given to me by Ian Rea in 2013. He rescued from
his place of work some years ago when the calibration department was
closed. The other stuff went in the bin but he didn't have the heart to
chuck this as it's such a beautiful item!
0.3% of FSD on DC voltage ranges
0.5% of FSD on DC current ranges
0.75% of FSD on AC ranges (assuming FF of 1.11)
true value= 1+.0003(t-20)
where t is ambient temperature in edges Centigrade
The detachable lid houses the connecting leads and the test certificate dated 17/12/1973
The internal construction has echoes of the more workaday AVO meters.
The wire wound resistor boards are supported in a mahogany wood frame and the switches are ingeniously interlocked, the current and voltage selectors cannot be turned until the centre switch is correctly positioned.
The serial number indicates that this meter was made in May 1967.
For further information have a look at my pages on the model 8
AVO and Test Meter No1 here and here