Service manual

10 Agilent 382A Operating and Service Manual
Operation
NOTE This procedure does not correct for other system errors
8. Repeat this measurement with the attenuator under test set to 10, 20, 30,
40, 50 dB and MAX attenuation. The SWR must remain less than 1.15
(25 dB return loss calibration line) throughout the frequency range of the
attenuator under test. If any of these traces go through the calibration
line the attenuator may or may not be out of specifications depending
upon how the extra reflections in the system combine. To determine the
true SWR at these doubtful frequencies use the single frequency. See
SWR test which follows.
9. Connect the other port of the attenuator to the test setup and repeat steps
4 through 8. If the SWR is out of specifications check for warped,
broken, burned or wrinkled resistive cards. Check for silver paint or
foreign material in rotary choke joints.
Single Frequency
SWR Test
The swept frequency SWR test is preferred since it will show narrow
out-of-specification bands, which may be missed with spot checking by
means of this single frequency method. However, if equipment for sweep
testing is not available or if doubtful frequencies show up in
sweep-frequency testing use the following test:
1. In the setup of Figure2 on page8 connect a slotted line and SWR meter
between test setup and 382A under test.
2. Adjust carriage for maximum voltage on SWR meter.
3. Adjust sliding load for maximum voltage on SWR meter.
4. Repeat steps 2 and 3 since they interact.
5. Set GAIN on SWR meter for a meter reading of 1.0.
6. Move carriage to minimum voltage position (maximum SWR).
7. Move sliding load to maximum voltage (minimum SWR). Do NOT
readjust carriage.
8. Read SWR on meter. This is the true SWR of the 382A with the load
reflection cancelled out. However, any possible reflections from other
components of the system are not cancelled.