[volt-nuts] Newer Fluke 845ab manual with chopper mod?

Dallas Smith dosmith at outlook.com
Sat May 3 12:18:13 EDT 2014

Does anyone have the schematic for the Fluke 845 chopper modification as 
stated in front of manual to be released approximately Dec 1993?

Manual statement:
'The new circuit now employs optically-isolated Bilateral Analog FETs, 
and is fabricated on an additional circuit board.'

Frank, from Volt-Nuts 21 Mar 2010, suggested that: The 335A_D manual 
contains the coil chopper for the calibrator circuitry, (page 119/120) 
and the opto chopper version for the included Null volt meter, same 
circuitry as of the 845A/B. Compare this with the 335_D manual,(page 
169) where you can find the MOS FET version for the calibrator amplifier.

Has anyone tried this circuit for the Fluke 845ab?

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