David, I had to go research a bit. The primary difference between the A & D is output accuracy and stability. Roughly a 2 to 1 improvement. Keep in mind we are talking splitting hairs. Either one would exceed what one would normally need for a small home lab.
As for the Fluke 845, you simply cannot beat it. If it is not outrageous, grab it. Hopefully, it is the portable version which had the highest of isolation rating and gives you freedom from ground loops because it runs on batteries, but the rack mount version is nice as well ( I have both models). The Fluke 887 is a nice meter as well. They were very good in their time. However, a top of the Fluke or HP DVM would give them a run for their money. If the price is LOW, it wouldn't hurt to have one. The big draw back is having to operate all the switches to get a result. If your constantly operating the switches, they will wear out. So, it is not what I would consider a general purpose meter, but more of a backup reference standard. For normal stuff just use a cheap DVM. I have all the above equipment except Differential voltmeter is an earlier version, the 883AB, which is the same as the 887 with slightly less accuracy. Bill....WB6BNQ "David C. Partridge" wrote: > Hobbyist. > > The eBay bidding on the Fluke 335D is already going up ... > > I still own the 335A (though how long for is another question). > > Both the above are spares/repair as is the Efratom FRT (no lock). > > The vendor also has Fluke 845 and Fluke 887 and scarily also a 540B, but I > can't afford all that lot in one bite :( > > I have a Keithley 155 Null Detector how does that rate? > > Thanks > Dave > -----Original Message----- > From: [email protected] [mailto:[email protected]] On > Behalf Of WB6BNQ > Sent: 15 December 2012 02:31 > To: Discussion of precise voltage measurement > Subject: Re: [volt-nuts] Fluke 335A versus HP 740B > > David, > > The difference between the 335 A or D model I don't recall off the top of my > head specifically, but they were improvements. I would probably take the D > but really either one is good, assuming, of course, they are working. > > You might want to consider getting both of them. They can handle being 1000 > volts above ground. So with two you have a calibrated DC voltage up to 2000 > volts. > > You still need a good null meter. While the 335's null meter is OK, it does > not hold a candle to the Fluke 845 when it comes to isolation. > > Are you just gathering this stuff for your own use as a hobbyist or are you > intending to get into some commercial concern ? > > Bill....WB6BNQ > > "David C. Partridge" wrote: > > > And also what is the difference between a 335A and a 335D? > > > > Thanks again, > > Dave > > -----Original Message----- > > From: [email protected] [mailto:[email protected]] > > On Behalf Of David C. Partridge > > Sent: 15 December 2012 02:16 > > To: 'Discussion of precise voltage measurement' > > Subject: [volt-nuts] Fluke 335A versus HP 740B > > > > Both DC Voltage standards up to 1000V or so, and also null differential > > meters. > > > > Also both being sold by the same vendor as the other stuff > > > > Do the assembled mavens have a view as to which is preferable? > > > > Thanks > > Dave > > > > _______________________________________________ > > 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. > > > > _______________________________________________ > > 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. > > _______________________________________________ > 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. > > _______________________________________________ > 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. _______________________________________________ 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.
