Section 7
7-4
The procedure to calibrate a voltage range on the 6675A is as follows:
1) Go into the menu
<Main_SoftCal_Voltmeter_(select range)_Volts Set> and connect a
precision voltage source to the Rs-P
2
(High) and Rx-P
2
(Low) terminals.
2) Set the voltage source to 0 volts (and enable its output) and select the
<zero
volts> key. Do this a few times until the displayed count is stable in the
units digit.
3) Set the voltage source to 75% of range and enter this value with the
<Ref
volts>
key. Enable the voltage source output and measure this signal by
pressing the
<HighVolts> key. Do this a few times until the displayed
count is stable in the unit's digit.
4) Finally press the
<Ok> key to internally store these values in the internal
EEROM.
5) Exit this routine by selecting the
<PREVIOUS> key a few times to return
to the main menu.
6) Go into the menu
<Main_Voltmeter_(select calibrated range)> and check the voltmeter
range you have just calibrated.
7.1.3.3. ADC Beta.
For the 50Hz operation ADC Beta = 300 (nominally) and for the 60Hz operation
ADC Beta = 250 (nominally). The 6675A communications card/controller does not
use this number when it calculates voltages or resistor values. It is a number that is
reported to it from the nanovoltmeter processor so that it can be put up on display.
The nanovoltmeter controller gets the value for ADC Beta from dip switches that
are factory set on the nanovoltmeter processor card (and should not be changed).
To Next Page
Loading...