HP 8340B Manual page 237

5-5.
20/30
LOOP PHASE LOCK, A36, ASS, ASS, A40, AND A43 (Cont'd)
49. Connect the Function
Generator to A36TP3. Adjust the Function Generator amplitude to
place the
20 kHz signal displayed on the
Spectrum Analyzer at
the
0 dBm reference
line.
50. Set the Function Generator to 50 kHz.
51.
Set the Spectrum Analyzer
Marker at 50
kHz.
52. Adjust A36L7 and A36L8
(50
kHz
NULL) to
null the
50 kHz
signal displayed on
the Spectrum
Analyzer. Refer to
Figure 5-12 for location of adjustments.
53. Note the level of the 50 kHz
signal. This level should be at least
65 dB down
from the level of the 20
kHz response. Disconnect the test equipment from the
ASS
assembly.
54. Disconnect the active probe from the Spectrum
Analyzer
and connect the Spectrum Analyzer
input to
A36J2
(OUT 200-300 MHz)
using a
BNC
to
SMB
snap-on
test cable. Set the LINE switch
to
ON.
55.
Set the
Spectrum Analyzer as follows:
INSTR PRESET
................................ ..............
Press
START FREQ
...................................................
150
MHz
STOP FREQ
...................................................
470 MHz
REF LINE
....................................................
+10
dBm
MARKER
.................................................
PEAK SEARCH
56. Connect an external low-voltage dc
power supply positive lead to A36TP3
and the negative lead
to any convenient chassis ground. Set the external power supply for +16.0 Vdc
±
0.1
Vdc.
57.
The
Oscillator frequency should be 310
MHz ±10
MHz as indicated on the
Spectrum Analyzer
If
not, remove the metal shield from
A36
and increase or decrease the spacing between turns of
A36L4
and increase or
decrease
the area of the single turn of
A36L5
to properly tune the
oscillator.
58.
Change
the
power supply voltage to +4.0
Vdc ±0.1 Vdc.
59.
The
Oscillator
frequency
should drop below
200
MHz
with
an
amplitude greater than —7 dBm.
60. Repeat Steps 56 through 59
if
necessary to meet requirements.
61.
Set the LINE switch to STANDBY. Reinstall the metal
shield on
A36
if it
was
removed,
reinstall
A36
(PLL1
VCO)
in the instrument, and reconnect all
cables.
62. Remove A38 (PLL1 IF) from the instrument and
install
it
on an extender board. Connect
all the
cables to A38.
63. Set
the
LINE switch
to
ON
and press [INSTR
PRESET].
Press
[CW]
then enter
[1] [3]
[.]
[9] [7]
[MHz].
HP 8340B/41B
Adjustments
5-33