Keysight 34465A femtoamps? (typo 1 uA range)  - Page 1
Forum section: electronics / general

author: jonpaul
author_rank: Super Contributor
timestamp: December 08, 2021, 11:22:05 am
content: Bonjour a tous:We received a new 34465A (dark color) in warranty, with Keysight CAL cert, was $1150. Any others have bought these used?Checks of our lab standards, a few observations:Every voltage ref, resistance and capacitance are well within CAL.DC Voltage Zero ~ 1 uV with gold shorting jumper.ACV zero is 0.In current 1 uA range, we see ~ 1 pA open ckt, and sometimes read 500 fA with slow averaging.A 22000 GOhm Victoreen in series with 10 V Vref to generate a current ~ 500 pA.QUESTIONS:What is the ultimate zero others see on DC current range 100 uA ?Is there any different using front or rear inputs?Put unit on standby with power off, yellow LED . That standby keeps the int ref ON so warmup effects?OR, how long a warmup period is suggested?Does a real printed manual exist, the PDFs are hard for us to read.Many thanks for your kind assistance!Have an absolutely fantastic day!Jon in ParisPS: 34465A: WOW what a marvelous instrument! Quite a step up from my ancient Fluke 8842A!My only CAL work was a halcyon Summer spend in perhaps 1966 at Julie Research Labs in NYC, working with Loeb Julie.I still have some of their handwound resistors.

author: gamalot
author_rank: Super Contributor
timestamp: December 08, 2021, 12:10:34 pm
content: I am completely confused by your question, how can you read 1pA or even fA level results in the 100uA range on a 6.5-digit meter, do you mean the 1uA range?

author: 2N3055
author_rank: Super Contributor
timestamp: December 08, 2021, 12:31:50 pm
content: Jon,In "Keysight Truevolt Series Digital Multimeters, Operating and Service Guide" there is detailed performance verification procedure.Quick excerpt for low current ranges:OPEN condition (zero verification)1 µA ± 50 pA (50E-12 A)10 µA ± 200 pA (± 200.0E-12 A)100 µA ± 0.001 µAIn 1µA and 10µA ranges use or relative zeroing (Null) math function is recommended before measurements.Long term stability is not guaranteed in those ranges.Best regards,Sinisa.

author: HighVoltage
author_rank: Super Contributor
timestamp: December 08, 2021, 01:53:28 pm
content: Quote from: jonpaul on December 08, 2021, 11:22:05 amThat sounds about right, I have seen similar values on my 34465ABTW, you make make good and stable measurements down to 1 nA on this instrument.

author: Dr. Frank
author_rank: Super Contributor
timestamp: December 08, 2021, 01:58:47 pm
content: Quote from: jonpaul on December 08, 2021, 11:22:05 amHello,DCV and DCI zeros are that low, because your unit was recently calibrated, which at a first step makes a zero calibration for all modes, see manual.No, there is no printed version of the manual available. That's a real pain in the ass...If you would print it, it's still a mess, because it's made as a purely digital book with hyperlinks, with no linearly structured chapters..ACV is of course zero, as all HPAK bench multimeters cut off the reading to zero, when the level is below a certain margin.There was an article describing the AC linearity at low values, and about this cutoff.Carefully read the specification, foot note 15, it's mentioned there, that AC accuracy is only specified down to >0.3% of F.S.My unit from 2015 currently shows an average of -809nV in 100mV DC range with gold plated shorts.The 1µA DCI range only has a resolution of 1pA, and after warming up it shows an average offset current of about 500fA.Trick: go to math, switch scaling on with m = 1 and b= 0, and you get a much more convenient display of the statistical values, as well as on the main display as a floating engineering format. That's great to enhance resolution to 7 digits (not 7 1/2, unfortunately).You always need to zero the ranges, when making low value measurements (µV, pA), so your questions do not make so much sense.The orange LED only indicates that the DMM is plugged into mains, but the analog board and the LM399 reference unfortunately are not powered.The 34970A DAQ only has this nice feature, that the analog circuit is powered all the time.2h warm up time is sufficient for the 34465A to have full and stable accuracy, just check temperatures with menu Utility=> Test => Calibrate. The inner temperature rises about 2..3°C above room temperature. As the LM399 is warmed up and stable within 30sec, or so, you might (ab)use the ACAL feature to get quite accurate readings after a few minutes already.That's not timely stable, of course, and you need to repeat the ACAL after a while.Yes, the 34465A is a real nice, stable and very versatile DMM.Frank

author: mawyatt
author_rank: Super Contributor
timestamp: December 08, 2021, 03:24:40 pm
content: After about ~30 minutes warm up we see ~5pa with SD of ~900fa open circuit current on the KS34465A, the DMM6500 shows ~52pa and SD 11pa.Edit: Added Voltage short input offset which is -830nv SD108nv for KS34465A and 860nv SD 70nv for DMM6500.2nd edit: Added SDM3065X, 7na SD 1.3na and 3.1uv SD 170nv respectively.Best,

author: gamalot
author_rank: Super Contributor
timestamp: December 08, 2021, 05:01:25 pm
content: Here are the measurement results of my 34465A after warming up for 5 hours (it has never been calibrated since I bought it in November 2015)