>>"3. The 3458A still has got the best linear A/D, around 0.02ppm of input." >Is that a typo? Even 0.2 ppm would seem extremely good. I think I saw an >official number of 0.1ppm somewhere. Probably 0.1ppm of range. And how do >they implement that? Manual trimming and compensation? Hello Jan, well DNL, INL, sometimes I still struggle with those terms.. Those 0.02ppm were nonlinearity of input, measured with a JJ array. And they use a special multiple slope scheme, with glitch compensation for the switching FETs. Just download the April 1989 HP Journal, there's everything explained in detail. http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1989-04.pdf Frank

The other reason the price is so high is that the cost of entry for a competitor to develop and sell a comparable unit for such low sales volume would also cost that much if not more. The Fluke 8508 does cost more but it is a 3458A "under the hood". On Mon, Jan 20, 2014 at 3:09 PM, Frank Stellmach <frank.stellmach@freenet.de > wrote: > "3. The 3458A still has got the best linear A/D, around 0.02ppm of input." >>> >> > Is that a typo? Even 0.2 ppm would seem extremely good. I think I saw an >> official number of 0.1ppm somewhere. Probably 0.1ppm of range. And how do >> they implement that? Manual trimming and compensation? >> > > Hello Jan, > > well DNL, INL, sometimes I still struggle with those terms.. > > Those 0.02ppm were nonlinearity of input, measured with a JJ array. > And they use a special multiple slope scheme, with glitch compensation for > the switching FETs. > > Just download the April 1989 HP Journal, there's everything explained in > detail. > > http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1989-04.pdf > > > Frank > > > _______________________________________________ > 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. > -- John Phillips

The Fluke 8508 is actually more of a Wavetek/Datron 1281 under the hood. The real difficulty in introducing a 3458A competitor is that the scientific community has been characterizing the HP meter for three decades. It's quarks and idiosyncrasies are well know such as how it will drift, or react to environmental changes. Even a superiour meter will take years to be as usable. Thomas Knox > From: john.phillips0@gmail.com > Date: Mon, 20 Jan 2014 15:33:39 -0800 > To: volt-nuts@febo.com > Subject: Re: [volt-nuts] The 3458A A/D > > The other reason the price is so high is that the cost of entry for a > competitor to develop and sell a comparable unit for such low sales volume > would also cost that much if not more. The Fluke 8508 does cost more but it > is a 3458A "under the hood". > > > On Mon, Jan 20, 2014 at 3:09 PM, Frank Stellmach <frank.stellmach@freenet.de > > wrote: > > > "3. The 3458A still has got the best linear A/D, around 0.02ppm of input." > >>> > >> > > Is that a typo? Even 0.2 ppm would seem extremely good. I think I saw an > >> official number of 0.1ppm somewhere. Probably 0.1ppm of range. And how do > >> they implement that? Manual trimming and compensation? > >> > > > > Hello Jan, > > > > well DNL, INL, sometimes I still struggle with those terms.. > > > > Those 0.02ppm were nonlinearity of input, measured with a JJ array. > > And they use a special multiple slope scheme, with glitch compensation for > > the switching FETs. > > > > Just download the April 1989 HP Journal, there's everything explained in > > detail. > > > > http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1989-04.pdf > > > > > > Frank > > > > > > _______________________________________________ > > 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. > > > > > > -- > John Phillips > _______________________________________________ > 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.