Chapter 11 569
Synthesizer Section
Frequency Span Accuracy Problems
2. Determine the harmonic-mixing number from the information in
Table 11-13 on page 569.
3. Use the following equation to determine the 1st LO span used.
4. Refer to Table 11-12 on page 568 to determine the circuit associated
with the span.
Confirming Span Problems
1. First perform either the manual “7. YTO Adjustment” in Chapter 3 ,
or the automated “2. LO Frequency” and “3. YTO FM Coil”
adjustments in Chapter 2 .
• On the spectrum analyzer press
CAL, REALIGN LO &IF, and retest
all spans.
• If the YTO adjustment has sufficient range and only LO spans of
2.01 MHz or greater are faulty; test YTO linearity by performing
step c.
• Test the span in question at different center frequencies in the
same band. If the span accuracy changes significantly (2% or
more), suspect the A11 YTO.
2. If only 1st LO spans of 2 MHz or less are faulty, suspect the A14
fractional N PLL.
3. If there are several spans in the main coil and FM coil ranges
affected, suspect the A14 span attenuator.
Table 11-13 Harmonic Mixing Number versus Center Frequency
Center Frequency Harmonic Mixing Number
9 kHz to 2.9 GHz 1
2.75 GHz to 6.46 GHz 1
5.86 GHz to 13.2 GHz 2
12.4 GHz to 31.15 GHz 4
30.5 GHz to 50.6 GHz 8
18 GHz to 325 GHz 6 through 54 depending upon lock
harmonic selected
First LO Span
Display Span Setting
Current Band Harmonic Mixing Number
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