Service manual

Agilent 382A Operating and Service Manual 15
Operation
Attenuator
Calibration
Calibrate 10 dB System Error
Since we are to calibrate the attenuator in 10 dB steps we must first calibrate
the 10 dB attenuator on the SWR meter. To do this we substitute a calibrated
directional coupler. Proceed as follows:
Figure 6 Attenuator Calibration
1. Connect the instruments as shown in Figure 6.
2. Remove the 382A under test and reconnect the system (marked
"CALIBRATE" in Figure 6).
3. Set variable attenuator to 41 dB.
4. Peak SWR meter for maximum signal with 1000 Hz square wave
modulation at one of the calibration frequencies of the calibrated
directional coupler.
5. Set SWR meter to the 40 dB range and set to a reference point about
mid-scale on one of the expanded scales. Be sure this is well within the
square-law region of the detector (see Hewlett Packard Journal
July 1966, Vol 17, No. 11, pp 9-13).
6. Connect input and auxiliary output of directional coupler at the point
marked "CALIBRATE" in Figure6 on page15 (terminate main line
with matched load).
7. Set the SWR meter to 50 dB range.