HP 8562E, Service Manual

Page: 401 / 482

Check the fractional N oscillator (steps 13-17)
13. Set the spectrum analyzer to the following settings:
Centerfrequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...300 MHz
Span . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14. Monitor the fractional N PLL output at A145304 (FRAC N TEST) with a synthesized
spectrum analyzer such as an HP or HP Refer to function block AI of
Al4 frequency control schematic.
15. The signal at (FRAC N TEST) should measure approximately -10 at
66.7 MHz. If the loop is unlocked, the sampler IF frequency can also be seen on
about 30
below the fractional N signal.
16. If a problem exists only at particular CENTER FREQ and SPAN settings, determine
the desired fractional N oscillator frequency by pressing (CAL), ,
, and setting the HP 85633 to SINGLE trigger mode.
17. If the fractional N oscillator frequency is not correct, refer to “Unlocked Fractional N
PLL” in this chapter.
Check sampler drive output of A7 SLODA (steps 18-21)
18. Set jumper to the TEST position and set the spectrum analyzer to the following
settings:
Center frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.9
Span . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
19. Disconnect cable W34 from
20. Use a power meter to measure the A7 SLODA sampler-drive output at the end of W34.
The power should measure greater than -9
21. Place jumper in the NORMAL position and reconnect W34 to
Check sampler IF (steps 22-28)
22. Set the spectrum analyzer to the following settings:
Center frequency
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MHz
Span . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
23. Place jumper in the TEST position.
24. Disconnect W32 from Monitor the sampler IF output SAMPLER IF)
with a synthesized spectrum analyzer such as an HP or HP
25. The sampler IF should measure between 46 MHz and 86 MHz at -15 to
If the signal frequency or amplitude is incorrect, refer to “Unlocked Offset PLL” in this
chapter.
26. Set jumper in the NORMAL position. Reconnect W32 to
Check FM loop sense (steps 27-34)
27. Set jumper in the TEST position.
28. Set the spectrum analyzer to the following settings:
Synthesizer Section 1