artisan 8640B - Output Impedance Test (out of Band)

Model 8640B TM 9-4935-601-14-7&P
PERFORMANCE TESTS
4-26. OUTPUT IMPEDANCE TEST (In Band) (Cont'd)
2. Set voltmeter so that it can measure 100 mV. Adjust the stub for a minimum indication on power meter. Adjust
generator's OUTPUT LEVEL vernier for a 50 mV indication on voltmeter (
V
min).
3. Adjust the stub for a maximum indication on voltmeter. The voltmeter should indicate <100 mV (
V
max).
______________100 mV
4. Set generator's OUTPUT LEVEL switch one step ccw to 0 dBm. Set voltmeter so that it can measure 30 mV.
Adjust the stub for a minimum indication on voltmeter. Adjust generator's OUTPUT LEVEL vernier for a 10 mV
indication on voltmeter (
V
min).
5. Adjust the stub for a maximum indication on voltmeter. The voltmeter should indicate <13 mV (
V
max)13 mV 6.
Set generator's OUTPUT LEVEL switch one step ccw to -10 dBm. Set voltmeter so that it can measure 10 mV.
Adjust the stub for a minimum indication on voltmeter. Adjust generator's OUTPUT LEVEL vernier for a 5 mV
indication on voltmeter (
V
min).
7. Adjust the stub for a maximum indication on voltmeter. The voltmeter should indicate <6.5 mV (
V
max).
8. If desired, repeat at other frequencies between 256 and 512 MHz.
NOTE
The steps given above effectively check VSWR at all settings of the output attenuator (see
Service Sheet 13).
4-27. OUTPUT IMPEDANCE TEST (Out of Band)
SPECIFICATION:
Impedance: 50Ω, ac coupled, 40 Vdc maximum, VSWR <2.0 on 2V and 1V output ranges; <1.3 on all other ranges.
DESCRIPTION:
A tracking generator is used as an external 50Ω signal source to feed a VSWR bridge. The output port of the bridge is
connected to a spectrum analyzer. The through port of the bridge is connected to a short circuit to establish a reference,
then to the generator output. Return loss versus frequency is displayed on the spectrum analyzer.
4-39
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