Elgar SW5250A Service Manual download pdf (Page 42)

CALIBRATION TW SERIES

3-6

Calculate the gains and offset for the phase being calibrated:

GAIN1 = (MEAS1 – MEAS2) / (RDGN1 – RDGN2)

GAIN2 = (440.0) / (MEAS1 – MEAS2)

OFFSET = GAIN2 * MEAS1 – 220.0

Update the TW calibration registers by sending the following GPIB strings:

CAL{1,2,3}:MEAS:LOC:LOR:VOLT:GAIN GAIN2

CAL{1,2,3}:OUTP:LOC:LOR:VOLT:GAIN GAIN1

CAL{1,2,3}:OUTP:LOC:LOR:VOLT:OFFSET OFFSET

Reset the TW’s output to a safe condition:

SOUR{1,2,3}:VOLT:OFFSET 0.0

OUTPUT OFF

3.8 DC LOCAL HIGH RANGE CALIBRATION

Both the measurement and output subsystems are calibrated at the same time.

Connect the DMM to the output phase of the TW to be calibrated. Set the DMM for

auto–ranging volts DC. Send the following GPIB commands to the TW:

OUTPUT OFF

OUTP:COUP DC

Wait for the TW to complete its coupling change to DC. Continue with the following

GPIB command:

SOUR:VOLT:RANGE HIGH

SOUR:SENSE LOCAL

SOUR{1,2,3}:CURR 5.00

OUTPUT ON

SOUR{1,2,3}:VOLT:OFFSET 0.0

Wait for the DMM to settle and record the value as RDGN1.

Send the following query command to the TW and record the return string as MEAS1:

MEAS{1,2,3}:VOLT?

Calculate the offset value:

VALUE1 = RDGN1 – MEAS1

Send the offset value to the TW:

CAL{1,2,3}:MEAS:LOC:HIR:VOLT:OFFSET VALUE1

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Elgar SW5250A Service Manual Page 42