Electronics > Metrology

Keysight 34465A femtoamps? (typo 1 uA range)

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jonpaul:
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 Paris

PS: 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.



gamalot:
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?

2N3055:
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 µA

In 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.

HighVoltage:

--- Quote from: jonpaul on December 08, 2021, 11:22:05 am ---
In current 1 uA range, we see ~ 1 pA open ckt, and sometimes read 500 fA with slow averaging.

--- End quote ---

That sounds about right, I have seen similar values on my 34465A
BTW, you make make good and stable measurements down to 1 nA on this instrument.

Dr. Frank:

--- Quote from: jonpaul on December 08, 2021, 11:22:05 am ---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 100 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 Paris

PS: 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.

--- End quote ---

Hello,

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
   

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