Standard Communications mt930b, Руководство по обслуживанию, Страница: 43 / 155

Maintenance
MT930B Service Manual Page 6-11
Second IF Bandwidth (–3 and –25 dB) Measurement
Measurement Conditions:
• Use the network analyzer.
•
Input: 70 MHz IF LOOP IN (75 Ω ), 70
± 50 MHz, –30 dBm
•
Output: 70 MHz IF TEST (75 Ω )
• AFC: OFF
• AGC: OFF
• MGC: –30 dBm for 70 MHz IF TEST
Measurement Procedure:
1. Take the 70 MHz output level as the reference, and measure the frequency
bandwidth for –3 dB and – 25 dB.
2. Measure the frequency that is 3 dB below the level in step 1.
Measure each separate filter (16, 18, 22, 25, 27, and 36 MHz)
Measurement Specifications:
−−−− 16 MHz Bandwidth: –3 dB Bandwidth: 16 ± 1.0 MHz
–25 dB Bandwidth: ≤ 26.5 MHz
−−−− 18 MHz Bandwidth: –3 dB Bandwidth: 18 ± 1.0 MHz
–25 dB Bandwidth: ≤ 26.5 MHz
−−−− 22 MHz Bandwidth –3 dB Bandwidth: 22 ± 1.0 MHz
–25 dB Bandwidth: ≤ 34.0 MHz
−−−− 25 MHz Bandwidth –3 dB Bandwidth: 25 ± 1.0 MHz
–25 dB Bandwidth:
≤
37.0 MHz
−−−− 27 MHz Bandwidth –3 dB Bandwidth: 27 ± 1.0 MHz
–25 dB Bandwidth: ≤ 50.5 MHz
−−−− 36 MHz Bandwidth –3 dB Bandwidth: 36 ± 1.0 MHz
–25 dB Bandwidth: ≤ 60.5 MHz