Standard Communications mt930b, Руководство по обслуживанию, Страница: 40 / 155

Maintenance
Page 6-8 Service Manual MT930B
RF Input LO Leakage Measurement
Measurement Conditions:
• Set the equipment up as in Figure 6-4.
•
MGC: Maximum gain
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Figure 6-4. LO Leakage RF Input Equipment Setup
Measurement Procedure:
1. Connect the spectrum analyzer to J101.
2.
Connect a 75 Ω load to J102 through J104.
3. Set the input port to #1.
4. Vary the spectrum analyzer frequency from 900 to 2200 MHz, and measure
the spurious modulation level as the receiver frequency is varied from 950
to 2159 MHz.
5. Vary the spectrum analyzer frequency from 3.7 to 4.3 GHz, and measure in
the same manner.
6. Take the worst value as the measured value for local leakage at RF input
(at 0.9 to 2.2 GHz and 3.7 to 4.2 GHz).
7. Vary the test frequency from 0 to 20 MHz, 20 to 900 MHz, 2.2 to 3.7 GHz,
and 4.32 GHz and higher, and measure spurious modulation level for each
of these settings as the receiver frequency is varied from 950 to 2150 MHz.
8. Take the worst value as the measured value for local leakage at RF input
(all frequencies except –10).
9. Set the input port to 2 through 4, and repeat steps 4–8 for each port, con-
necting 75 Ω loads to the other ports.
Measurement Specifications:
LO Leakage
At 0.9 to 2.2 GHz and 3.7 to 4.2 GHz:
≤ –55 dBm
At all frequencies except the above:
≤
–45 dBm
As a convenience, a leakage test chart is at the end of this chapter. Feel free to
duplicate it and use it.