The noise spec on the 845 is 0.2 uV (if I remember correctly). Mine seems to be mostly within 0.1 uV. As far as battery replacement, I still used nicads (since I had them). One advantage of nicads over nimh cells is they are more robust. They tolerate overcharge better and have much better "shelf life". On a lot of replacements I do use the low self discharge NiMH cells. Their self discharge rate does seem to be greater than advertised... For circuits that trickle charge nicads (at say C/12), replacement with NiMH cells will give a C/36 charge rate (assuming three times the nicad capacity). This is OK, particularly if you don't leave them on charge permanently. Speaking of overcharging NiMH cells... I put a dead 3200 maH 6 cell pack on a constant 1.5 A charge and went to the local surplus store... no problem... back in a couple of hours. Got stuck in a nasty traffic jam, got back in 3.5 hours. The pack had exploded and let the magic smoke out of one of the cells... actually magic carbon dust. Parts of the pack were scattered over a 10 foot radius. Nasty black powder everywhere... parts of pack stuck to walls... etc... _________________________________________________________________ The New Busy is not the old busy. Search, chat and e-mail from your inbox. http://www.windowslive.com/campaign/thenewbusy?ocid=PID27925::T:WLMTAGL:ON:WL:en-US:WM_HMP:032010_3

Oops! Forgot to check the manual. Your memory is correct. Mine meets the noise spec. but the zero control covers too large a range and consequently it's impossible to turn it in small enough increments to zero perfectly. This is what the 845AB manual says about noise (and zero): ------------------------------------------------------ MAXIMUM NOISE (input shorted) RANGE NOISE (peak-to-peak) 1 µV 0.20 µV 3 µV 0.25 µV 10 uV - 1000 V 0.30 µV STABILITY OF ZERO Better than 0.15 µV/hour Better than 0.3 µV/day TEMPERATURE COEFFICIENT OF ZERO Less than 0.1 µV/°C from 15° C to 35°C Less than 0.2 µV/°C from 0° C to 50°C ZERO CONTROL RANGE ±5 µV minimum ------------------------------------------------------ Alan ----- Original Message ----- From: "Mark Sims" <holrum@hotmail.com> To: <volt-nuts@febo.com> Sent: Friday, March 19, 2010 6:35 PM Subject: [volt-nuts] Fluke 883AB differential voltmeter > > The noise spec on the 845 is 0.2 uV (if I remember correctly). Mine seems > to be mostly within 0.1 uV. > > As far as battery replacement, I still used nicads (since I had them). > One advantage of nicads over nimh cells is they are more robust. They > tolerate overcharge better and have much better "shelf life". > > On a lot of replacements I do use the low self discharge NiMH cells. > Their self discharge rate does seem to be greater than advertised... > > For circuits that trickle charge nicads (at say C/12), replacement with > NiMH cells will give a C/36 charge rate (assuming three times the nicad > capacity). This is OK, particularly if you don't leave them on charge > permanently. > > Speaking of overcharging NiMH cells... I put a dead 3200 maH 6 cell pack > on a constant 1.5 A charge and went to the local surplus store... no > problem... back in a couple of hours. Got stuck in a nasty traffic jam, > got back in 3.5 hours. The pack had exploded and let the magic smoke out > of one of the cells... actually magic carbon dust. Parts of the pack > were scattered over a 10 foot radius. Nasty black powder everywhere... > parts of pack stuck to walls... etc... > _________________________________________________________________ > The New Busy is not the old busy. Search, chat and e-mail from your inbox. > http://www.windowslive.com/campaign/thenewbusy?ocid=PID27925::T:WLMTAGL:ON:WL:en-US:WM_HMP:032010_3 > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there.