charlie, you can expand these tvcs by range resistors to work as higher voltage tvcs. if you do it right (rf-type setup) you can work up to a couple hundred khz with just minor additional error beyond its error in its orgininal voltage range. need to calibrate them however. using an attenuator is not a good idea, too unprecise. still tvcs are the most precise way to measure, if done right. pretty tme consuming though. but you need them e.g. to calibrate a 4920.
adrian > Gesendet: Sonntag, 31. August 2014 um 21:41 Uhr > Von: "Charles Black" <cbl...@centurytel.net> > An: "Discussion of precise voltage measurement" <volt-nuts@febo.com> > Betreff: Re: [volt-nuts] Datron 4920M, AC Voltmeter, for sale on ebay - 1 day > left > > Hi Stephen, > > Thanks for the info on the 4920M. It might be that I should pass on this > but it is nice to know that it is probably working. If I don't have the > necessary items needed for calibration it might still be a good source > uncalibrated. > > I was hoping that the 4920 had better minimum voltage out steps than my > present Rigol 4062 for 3458a AC calibration. I have two EL 1400 0.25V > voltage thermal converters that I was trying to use in a test setup but > they had such a low voltage range that I was forced to use my ATV-60 > attenuator. It all kind of worked but a 0.1 db minimum step is a little > course for easy use. The Rigol also suffers from this malady. > > Charlie > > On 8/31/2014 1:06 PM, Stephen Grady wrote: > > Charlie, > > > > > > The "Error Ur" is an under-range error; you have to apply an input above > > 10% of the range before it will display a reading. The 4920's are a very > > nice instrument. Their only problem is that they are all so old that they > > are reaching the stage where some components are drifting excessively or > > failing. I have come across 4920's that are drifting a little (more than > > there spec) between cals (and yes they need to be cal'd annually), another > > 4920 I came across had an intermittent failure in one of its power supplies. > > > > Kind Regards, > > > > Stephen Grady > > Sydney Australia > > > > -----Original Message----- > > From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of Charles > > Black > > Sent: Monday, 1 September 2014 3:19 AM > > To: b...@veritechmeasurements.com.au; Discussion of precise voltage > > measurement > > Subject: Re: [volt-nuts] Datron 4920M, AC Voltmeter, for sale on ebay - 1 > > day left > > > > Hi Ben, > > > > I am going to check this out today to find if it might be helpfull around > > here for my AC calibration. It has an error message: "Error Ur" > > so some fixing is going to be needed. On the back it says it's got Option > > 80, whatever that is. > > > > Charlie > > > > > > On 8/31/2014 5:37 AM, ben wrote: > >> Hello all, > >> Just a heads up. I noted there is a lonely Datron / Wavetek 4920M AC > >> voltmeter for sale on ebay, starting at US$650 (ending in 1 day !). I > >> have little idea of its true working state or not (picture shows it > >> powered on). > >> If fully working it would be a good buy for an AC voltmeter that is, I > >> reckon, better than an HP 3458A. Only drawback with these models is > >> the voltage input shell is always earthed, not floating. I have two of > >> these 4920M's already, not really tempted by a third. I have a paper > >> copies of operator, calibration, and service manual if anyone interested. > >> > >> regards, ben. > >> _______________________________________________ > >> 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. > >> > >> > >> > > > > _______________________________________________ > > 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. > > > > > > --- > > This email is free from viruses and malware because avast! Antivirus > > protection is active. > > http://www.avast.com > > > > _______________________________________________ > > 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. > > > > > > > > > _______________________________________________ > 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. _______________________________________________ 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.
