Dallas wrote:
Did Fluke ever make the 845ab Null Meter with the optically-isolated Bilateral Analog FET chopper?
I have never seen an 845 with FET chopper, despite the engineering change specification most 845 owners have seen. I've heard of one or two 845s that may have been repaired (by Fluke) with a FET chopper assembly (perhaps using 335D parts ??), but I'm not sure any 845s left the factory that way.
These days, there are integrated chopper-stabilized ("zero offset") op amps that can do better than chopper amplifiers (e.g., LTC1050, LTC1052, LTC2054, LTC2057, LTC7652, ICL7650, MAX4238/4239). Randy Evans started two threads here back in December 2013, one on modifying the Fluke 887 and one on modifying the 845. He made available his notes, which were quite thorough. Check the archives starting on Dec. 22, 2013.
Best regards, Charles _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
