HP 8901B Operation And Calibration Manual page 400

Model
8901B
Adjustments
Resistance
(ohms)
5. Fine tune the signal
s o m e up slowly until a zero beat signal appears on the oscilloscope. Then
increase
the signal source frequency by 1 kHz. Note the fhquency of the signal source. Note
the peak-to-peak amplitude on the oscilloscope.
HP
Part Number Capacitance(pF) H P Part Number
Signal Source kequency:
MHZ
Waveform Amplitude: mvPP
6. Tune the signal source up by 29.0 kHz.
This tunes
the high-frequency VCO up 32
x
30 kHz
M
1 MHz since the LO frequency is the
H F VCO
frequency divided by 32 on
this
band.
7 .
M u s t A23R34
(OF3 such that
when the input coupling of the oscilloscope is changed &om ac
to
dc the waveform shifts
upward 50 mV. Adjust A23R34 only when the input coupling is
set
to
dc.
8 . A d j u s t
A23R54
0
for the same peak-to-peak amplitude on the oscilloscope as noted in step
5.
I f the adjustment has not enough range:
a. Set A23R54 fully ccw and repeat steps 5 to 7.
b. The signal amplitude step 5. Should be greater
than
in step 8, with A23R54 adjusted fully
ccw. If it is not, replace A23R55 by higher values of resistance as listed in the following
table. If
this
still does not have enough effect, replace A23C45
with
higher values of
capacitance as listed in table below.
c. Adjust A23R54 for the same amplitude as noted i n step 5.
9. Repeat step 7 .
10. Key in 54.0 SPCL to run the LO
tuning test. The display should show 0.
51
1
750
1000
1210
1470
1780
0757-041 6
0757-0420
0757-0280
0757-0274
0757-0278
0757-1 094
1.8
2.7
3.3
3 . 9
01 60-4490
01 60-3568
0 1 60-4382
01 60-461 8
rev. 01 JUL91
Adjustment
4
5-9