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6611C-J05 Low-Range Current Measurement Calibration Issue!

Question asked by mgoldshteyn on Sep 29, 2015
Latest reply on Sep 30, 2015 by mgoldshteyn
In the +66312A Dynamic Measurement DC Source and 661xC DC Power Supplies User Guide+, Figure B-1, it says to use a 400 ohm resistor for calibration of the 6611C power supply's Low-Range Current Measurement. I assumed that this includes the 6611C with option J05 (i.e., 6611C-J05), a Keysight fully supported/currently manufactured and sold power supply from the 661xC series that is not mentioned in this guide (??). Apparently this is not the case. To be specific:

When I try to use a 400 ohm resistor (399.3 ohms, +/- 20 ppm/C, 5 W) in series with an ammeter as shown in Figure B-1 (B) and follow the procedure for calibration of the Low-Range Current Measurement on page 61 of the guide, I get a test voltage of about 9.76x volts which results in a current reading of somewhere in the neighborhood of 24.4xxxx mA (going from memory here) on my ammeter. When I try to enter this value into the unit as 0.0244... A as part of Step 22, I get an OUT OF RANGE error. Also, as I am going through the calibration procedure after the unit supplies the necessary voltage to the circuit (i.e., after the CAL:LEV P1 is selected after the completion of Step 21), the current reading on the unit itself shows overflow as well, indicating to me that:

1. The unit is trying to supply close to the maximum voltage that would result in a current of less than 20 mA through the resistor load.
2. A 400 ohm resistor is too low of a value to use to calibrate the 6611C-J05 Low-Range Current Measurement. 

Based on the Calibration Load Resistor values shown in Figure B-1 for other units in the 661xC series, I believe that the correct value for this resistor should be 500 ohms for the 6611C-J05, since this supply has a max voltage of 10 volts. This is a scaling of the 400 ohm resistor that should be used for the regular 6611C with its 8 volts max to the 10 volts max voltage that the 6611C-J05 is capable of supplying.

If anyone can confirm this assessment or has other ideas, please let me know.

Thanks  

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