HP 8562E, Service Manual

Page: 419 / 482

Sampler and Sampler IF
The sampler creates and mixes harmonics of the sampling oscillator with the first
LO. The resulting sampler IF (60 MHz to 96 MHz) is used to phase-lock the YTO. The
sampler IF filters unwanted products from the output of
and amplifies the IF to a
level sufficient to drive the YTO loop. When the IF is between 78 and 87 MHz, PIN diodes
switch a 120 MHz notch filter in the sampler IF section.
1. Set the spectrum analyzer to the following settings:
Center frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MHz
Span . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2. Disconnect W32 from
3. Connect the input of a power splitter to Connect W32 to one of the splitter
outputs. Connect the other splitter output to the input of another spectrum analyzer.
4. If a 66.7 MHz signal, greater than -15 is not displayed on the other spectrum
analyzer, set a microwave source to the following settings:
Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Amplitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -5
5. Connect the microwave source to A 66.7 MHz signal at approximately 0
should be displayed on the other spectrum analyzer.
6. Use an active probe/spectrum analyzer combination to measure the signal at the following
test points:
66.7 MHz, -8
296 MHz,
7. If a correct signal is seen at but the signal at is wrong, proceed as
follows:
Use an oscilloscope to measure the signals at the following test points:
pin 1
pin 3 Vdc to Vdc Vp-p variation)
-0.8 Vdc to -1.6 Vdc Vp-p variation)
If these levels are wrong, perform the “Power and Sampler Match Adjustments” in the
sampler oscillator adjustment procedure. Refer to Chapter 2, “Adjustment Procedures.”
If adjusting the sampler match does not bring the signal at
within
specification when the signal at is correct, the sampler is defective.
8. The sampler IF signal at is 60 MHz to 96 MHz at -10 to If the
signal at is correct, but the signal at is wrong, the fault lies in the
sampler IF circuitry. Continue with the following steps.
9. Set the HP 85633 to the following settings:
Center frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Span . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Synthesizer Section 11-45