Yes, my 845AB has a pretty sensitive null control. I can get it to zero without too much fiddling. There is some filter lag between tweaks and meter movement. I checked all the electrolytic caps and replaced a couple of suspect ones. I just rebuilt my Fluke 343A DC calibrator. It started acting funky after a 24 hour power failure. The output would cycle up and down about 30% over a 1 minute period. Turns out about 6 small electrolytic caps went. All is now well. The thing is spookily stable. 1 uV to 1000 volts outs. Not too bad for 50 bucks. Wish it did AC. I have a 5200A ac calibrator but it only goes to 100V. The 5205 power amp weighs about 100 pounds and uses vacuum tubes for the output. _________________________________________________________________ Hotmail: Trusted email with powerful SPAM protection. http://clk.atdmt.com/GBL/go/210850553/direct/01/