ITTSB.EU Blog Forum
Electrical Test and Measurement instruments => Bench-top multimeter => Topic started by: Kiriakos GR on December 29, 2025, 11:52:03 AM
-
Its not the first time that FLUKE 8846A documentation, this found to be at lowest standards.
DIODE Test Mode this is another poorly documented function in English.
Over the years FLUKE Corporation in the USA, this share the duty of writing of localized marketing material at several FLUKE owned offices around the globe.
Most well made documentation, its paper work made by FLUKE Japan !!
Over such a documentation, I found also the note that 8845A/8846A they were designed to test all sort of diodes, LED and even Zener diodes up to 10V.
Today neither AI this is aware of the actual capabilities of voltage and current source over the 8846A. :P
8846A open-circuit voltage at 5V mode = 6,140 VDC (1mA output & 10,1 M Ohm DMM input)
8846A open-circuit voltage at 10V mode = 12,825 VDC (1mA output & 10,1 M Ohm DMM input)
8846A current source 1mA = 1005,0 uA ( 0~400mA HH DMM input)
8846A current source 0.1mA = 100,68 uA ( 0~400mA HH DMM input)
Test performed at 16C environmental.
Current source 0.1mA, this is for special low power high precision diodes, that electricians will never touch. :)
Lets check what competitors do ...
Truevolt Series by KS, three models at 5.05V Max
KS 3458A Up to 12 V (mode dependent)
Legacy KS 34401A model, which only provided 1.2V
Keithley 2000, , including 3V and even a high-voltage 10V range for specialized testing.
Thanks God that FLUKE retired 8845A/8846A and made all their competitors to smile again. :(
-
My fresh discovery, a good advice from Vishay Semiconductors
Zener values from 1 to 10 V, they should be tested for 30 seconds, prior us accept the measurement as valid. :)
Note that the temperature of the ambient* has also an important influence of the reading, according to its thermal
coefficient of Zener voltage.
* All methods must be done at a recommended ambient temperature 25 °C +/- 1.
https://www.vishay.com/docs/84118/84118.pdf (https://www.vishay.com/docs/84118/84118.pdf)
-
Another aha moment. :P
8845A/8846A Digital Multimeter Users Manual July 2006 © 2006 Fluke Corporation
Checking Diodes
The diode function sends a current through a semiconductor junction while the Meter measures the voltage drop across the junction (or junctions). Measurements are displayed in the 10 V range at the medium and fast measurement rates.
"OPEN" is displayed for voltages 10 % above the compliance voltage setting.
Typical junction voltage drop on good junctions are 0.3 to 0.8 volts.
If enabled, the beeper will make a short beep when a good junction is detected.
Shorted diodes will indicate a significantly lower voltage.
With the higher compliance voltage (up to 10 V), the Meter’s diode test function can test zeners up to 10 volts, diode stacks and LEDs.
The selectable current allows you to tailor the diode test to the expected voltage for the junction being tested.
Function modifiers:
Four soft keys allow changing the test voltage and current applied to the diode through the test leads.
The compliance voltage is set to either 5 volts or 10 volts.
The compliance current is set to either 1 mA or 0.1 mA.
Press the appropriate soft key to select the desired voltage and current setting.
It makes you wonder, of how many revisions of Users Manual, Fluke Corporation wrote, and with whom they shared it with. :P
-
So the magical 8846A Digital Multimeter, it can also measure the actual Zener output voltage !!! 8)
This is also great assistance, if you have Zener diodes in storage, that markings text this has fade out. ;)
Diode stacks = HV DC applications, such measurements should be made only at disassembled PSU.
For fellow electricians not aware of Zener diodes, I just found at YT relative video footage.
https://www.youtube.com/watch?v=RSHahPnioW0 (https://www.youtube.com/watch?v=RSHahPnioW0)
-
So the magical 8846A Digital Multimeter, it can also measure the actual Zener output voltage !!! 8)
This is also great assistance, if you have Zener diodes in storage, that markings text this has fade out. ;)
Yes it does that too 8)
About Zener diodes, I was not aware that 5V and bellow they do not have such a sharp knee.
This translates that a 4.2V Zener, this will not measure as this to be a voltage reference. :)
I will pause for now additional Zener diodes testing, until environmental temperature this elevates at 22C at least.
So to redo measurements at my 10V Zener (tested sample), I think that voltage output this will improve at four digits resolution.
If I measure 10.00xx this I will call it success. :)