HP 8340B Manual page 230

5-4.
M/N
LOOP, A32,
ASS, AND A32A1
(Cont'd)
6.
Connect DVM to A32TP1 TUNE
test point. Refer to Figure 5-8
for location of A32 assembly.
7.
Loosen locknut
on A32A2C1 FREQ ADJ control and
adjust
A32A2C1
for
a
DVM
reading of
-35.0
Vdc
±0.5
Vdc. Retighten A32A2C1 locknut. Verify that DVM
reading
is still
within
tolerance.
8. Press
[CW]
on the
DUT,
then enter
[2]
[3] [0] [0]
[MHz].
9.
Turn the Spectrum Analyzer's
Signal
Track
off and then set the Spectrum Analyzer for
a
Center
Frequency
of 179.230
MHz.
Turn the Signal
Track
on. The
frequency
indicated on Spectrum
Analyzer should be 179.230 MHz ±1 count and the
DVM
should read
-2.8
Vdc
±
1.0 Vdc.
10.
Set the DUT's LINE
switch
to STANDBY.
11. Disconnect the
DVM from the A32
assembly. Remove
the
A32/A33
assembly from the instrument
and place
it
on an extender board.
12. Disconnect the
A32 output cable A32A1 W1
from A33J3 (Figure 5-8) and
connect
this cable using
SMB
male-to-male adapter to the input of the
Spectrum Analyzer. Set the DUT's LINE switch
to
ON
and
press
[INSTR
PRESET].
13.
Turn the Spectrum Analyzer's Signal Track
off and then set the Spectrum Analyzer Center
Fre¬
quency to
375 MHz,
the Frequency Span
to 100
MHz, Log Scale 5dB/Division, and the
Reference
Level to
+5
dBm.
I
CAUTION
)
ViM^MfM^M
Do not apply
a
positive voltage to A32TP1 or damage may occur to
the
VCO tuning diodes.
14. Connect the low-voltage power supply to the
OUT as follows: Positive lead to ground (do
this
first). Negative lead to A32TP1 TUNE test
point.
Set
the output
of the supply for
-35.0
Vdc
±0.5 Vdc.
15.
Adjust A32A2C5 PWR for
a
VCO
output level of
0 dBm
±
2
dB as indicated on Spectrum
Analyzer. Refer
to Figure
5-8 for location of adjustment.
16. Slowly reduce the voltage output of the external low-voltage power supply connected
to
A32TP1
TUNE test point while monitoring the VCO output
level on the
Spectrum Analyzer
and voltage level on
DVM.
17.
The VCO
output level should be greater than
-2
dBm between 395 MHz
(-35
Vdc) and
355 MHz
(-2.8 Vdc).
18.
Repeat Steps
2
through
9
to check frequency accuracy.
19.
Set the
DUT's LINE
switch to STANDBY.
Disconnect
all the test equipment from the
A32/
A33 assembly. Reconnect the cable
A32A1 W1
to A33J3.
20. Reinstall the A32/A33 M/N Output Assembly and remove the jumper from A59TP4
to
A59TP5 (UNLK
indicator disable).
21.
Disconnect the cable from the DUT's rear-panel EXT FREQUENCY STANDARD,
recon¬
nect the BNC cable between the INT and EXT connectors, and set the adjacent switch
to
INT.
HP8340B/41B
Adjustments
5-25/5.26