Standard Communications mt930b, Service Manual

Page: 47 / 155

Maintenance
MT930B Service Manual Page 6-15
IF Output Level and Frequency Measurement
Measurement Conditions:
•
Input: 950 to 2150 MHz at –20 to –65 dBm (75 Ω )
•
Output: 70 MHz IF TEST
• AFC: ON (Fine tune VR: Center detent position)
• AGC: ON
Measurement Procedure:
1.
Measure the 70 MHz IF output level with the spectrum analyzer. This is the
IF output test level.
2.
Measure the 70 MHz IF output frequency with the frequency counter. This is
the IF test point output frequency.
Measurement Specifications:
IF TEST Output Level: –30 dBm ± 2.0 dB
IF TEST Output Frequency: 70 ± 0.1 MHz
Overall 20 MHz Bandwidth Ripple Measurement
Measurement Conditions:
• Measure with the scalar network analyzer.
•
Input: 950 to 2150 MHz at –20 to –65 dBm (75 Ω )
• Output: 70 MHz IF TEST
• AFC: OFF
• AGC: OFF
• MGC: 70 MHz IF (the point where the IF output becomes –30 dBm)
Measurement Procedure:
1.
Vary the signal generator center frequency from 950 to 2150 MHz , and set
the test frequency of the UUT to the center frequency of the signal generator.
Verify that the frequency has the largest ripple at center frequency
± 10 MHz.
2.
Measure the ripple of the center frequency ± 10 MHz at the frequency
with the largest amount of ripple (represented as a ± value when the center
frequency is taken as 0 dB).
Measurement Specification:
Overall 20 MHz Bandwidth Ripple: ≤ ± 2.0 dB