HP 8560E, Service Manual

Page: 118 / 665

Chapter 2 117
Adjustment Procedures
16. Signal ID Oscillator Adjustment (serial prefix 3517A and below)
7. Press
INSTR PRESET
on the HP 8566A/B and set the controls as
follows:
Center frequency .............................................................. 12.7 MHz
Span .................................................................................... 500 kHz
8. Set the HP 5343A controls as follows:
Sample rate ................................................ .Fully counterclockwise
50
Ω
— 1 M
Ω
SWITCH .......................................................... 50
Ω
10 Hz — 500 MHz/500 MHz — 26.5 GHz switch ............10 Hz — 500 MHz
9. If no signal is displayed on the HP 8566A/B, adjust A15C629 SIG ID
until a signal is displayed.
NOTE
If the 298 MHz SIG ID oscillator is severely mistuned, it might be
necessary to widen the span on the HP 8566A/B to see the IF signal.
10.Rotate A15C629 SIG ID slightly while observing the HP 8566A/B
display.
NOTE
The nominal counted frequency should be 12.7 MHz, not 10.7 MHz.
11.While observing the HP 8566A/B display, adjust A15C629 SIG ID for
the highest obtainable frequency, with less than 3 dB decrease in
amplitude from maximum. Read this frequency from the frequency
counter and record as F
3 dB HIGH
.
F
3 dB HIGH
=
_________________________
MHz
12.Observe the HP 8566A/B display as you adjust A15C629 SIG ID for
the lowest obtainable frequency, with less than 3 dB decrease in
amplitude from maximum. Record the frequency counter reading as
F
3 dB LOW
.
F
3 dB LOW
=
__________________________
MHz
13.Calculate the difference between F
3 dB HIGH
and F
3 dB LOW
, then
divide results by four. Enter the result as F
OFFSET
.
F
OFFSET
=
___________________________
kHz
14.Add F
OFFSET
to F
3 dB LOW
recorded in step 10 and record the result
as F
SIGID
.
F
SIGID
=
_____________________________
MHz
15.Adjust A15C629 for a frequency counter reading equaling F
SIGID
.
The final adjusted frequency must equal 12.7 MHz
±
50 kHz.