Finally, here's my story, up to now..
I got my 34465A end of June, GPIB and DIG options.
Very nice instrument, compared to my 34401A from 1993.. especially the comfortable graphical interface and all these direct access / display features. Big win ! Also see other post about 2 very mighty digitizing measurements, I already did with this instrument (DCV and DCI).
Now to the bugs I very soon discovered.
The calibration date had been 3 weeks earlier, 2nd June, with very freshly calibrated Fluke 5720A.
As the instrument already had been produced in January, Keysights calibration policy required a 2nd calibration run before delivery, as 3 months had passed in between (No orange sticker any more!)
Normal calibration is exactly 76, would have been 152 for my instrument, but it came with 222!
Very odd already.
I always check new instruments on receipt.
Have to say, that I own a 3458A, and a Fluke 5442A, which both are uncertain to about 1ppm in DCV, on all DCV ranges .. otherwise I wouldn't have had the chance to find these bugs..
OK, I checked 100mV, 1V, 10V DCV. All three ranges were in accordance to my equipment within < 1ppm!
With each instrument, there's a "Certificate Of Calibration" and a verification Test Report on the backside, which contains the read-back of some of the just-before calibrated modes and ranges.
These DCV ranges were also spot-on during verification, as expected, i.e. less than 1ppm.
So were 10KOhm and other modes.
2nd odd thing now was, that the divide-by-hundred HV ranges, i.e. 100V, 500V and 1kV were all off by 6 .. 14ppm.
(Again, the 3458A and the 5442A both do exact 10V => 100V transfers , < 1ppm uncertainty, by auto-calibration!!)
That already caught my eye, as such an instrument should not drift so far off, in 3 weeks time, and without any possible voltage / power burden in between, when all the lower DCV ranges were spot-on..
The 100:1 divider should also be stable, at least it should not drift by 16ppm.. that would bust the 90d limit as it would bust the 1yr. limit.
Anyhow, I now re-calibrated the HV ranges only, by applying 100V and 500V, as described in the manual.
After storing the cal constants, the instrument displayed exactly 100.00000V, 500.0000V and 1000.0000V, within 1ppm (the 34465A displays 7 digits, if using statistics math function), as expected, and as already checked during verification at Keysight.
Temperature is constant to a few tenths of °C in my lab, during short term measurements, by the way.
As soon as I triggered the ACAL function, the very same calibration offset as before was introduced, i.e +9ppm for 100V, +16ppm for 1kV range. I repeated that several times, but very obviously , the ACAL does not work correctly in the HV ranges. It irreversibly busts the calibration.
Specification is at least violated, as ACAL claims to improve the T.C. from 5ppm/K to 1ppm/K.
Also the 90d limit will be violated, if additional drifts occur.
Changing the inner temperature lead to even more crazy ACAL readings.
I strongly assume a firmware error . The exchange instrument, I received a few days ago, is also spot on in the low DCV ranges, but off by around 10ppm on the HV ranges. (Already FW 2.09)
The 2nd bug is accessible to everybody, and confirmed already on both 34465A, and also on a 34470A.
(All TueVolt DMMs share the same FW 2.08 or 2.09)
If you apply a constant voltage on the HV ranges, like 100V on the 100V range, change the impedance setting from AUTO to 10MOhm.
The instrument is definitely fixed in the 10M divider mode, so there is absolutely no change in the hardware setting.
Anyhow, the reading will increase by +3ppm, reversibly.
Only explanation is a firmware bug also.
3rd bug is a mechanical one.
The lever of the front / rear switch is much too flexible. The plastics is too soft or too thin, so it bends by engaging the Shadow switch.
In my case, releasing the switch to front input again, did not feel fine, and the switch often was hooked.
The occurrence of this error depends on the spring force of the switch, I think.
Typical mechanical design fault.
Anybody else might also check these faults on his own instrument, even though the first fault is only evident to 34465A/34470A owners, and who were capable of checking 100V and 1kV calibration very stably / precisely.
I expect an analysis from Keysight, and hope for confirmation and repair of the assumed faulty firmware.
I have to say, that the reception of this assumed fault by Keysight is very good (starting with kind assistance by Mike Kawasaki), and the support extremely alert, as I already got another new instrument, and they wish to analyse the "defect" instrument in their development in Malaysia.
Frank
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