Cal Power TrueWave TW1750, Service Manual

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CALIBRATION TW SERIES
3-28
Wait for the DMM to settle and record the value as RDNG2 .
Calculate the gain and offset for the external input:
GAIN = 60.0 / ( RDNG2 – RDNG1 )
OFFSET = 10 – ( RDNG2 / (42.0 * GAIN ))
Open the output relay and turn off the external gain port with the following GPIB
commands:
OUTPUT OFF
SYST:EXT:GAIN 0
Send the updated calibration constants to the TW with the following GPIB strings:
CAL:UNIQ:GEXTG GAIN
CAL:UNIQ:OEXTG OFFSET
3.19 LOW RANGE CURRENT CALIBRATION
Connect the 12 ohm resistor to the output of the TW through the power analyzer. Set
up the power analyzer to measure current.
Set up the TW to DC coupling, low range, local sense, 13 ampere current limit, output
relay closed and 12 volts with the following GPIB programming strings:
OUTP:COUP DC
SOUR:VOLT:RANGE LOW
SOUR:SENSE LOCAL
SOUR
{1,2,3} :CURR 13.00
OUTPUT ON
SOUR
{1,2,3} :VOLT:OFFSET 12
Wait until the power analyzer has stabilized and record the current reading as RDNG1 .
Query the TW’s current using the GPIB string below, and record this value as MEAS1 .
MEAS {1,2,3} :CURR?
Program the TW to 120 volts DC using the string below:
SOUR {1,2,3} :VOLT:OFFSET 120
Wait until the power analyzer has stabilized and record the current reading as RDNG2 .
Query the TW’s current using the GPIB string below, and record this value as MEAS2 .
MEAS {1,2,3} :CURR?