HP 8340B Manual page 432

5-16.
LEVELED RF OUTPUT ADJUSTMENTS (Cont'd)
Equipment
Oscilloscope
...................................................
HP 1741A
10:1 Divider Probe,
2
Required
.................................
HP 10004D
Detector
.....................................................
HP 8473C
Digital
Voltmeter (DVM)
.........................................
HP 3456A
Adapters:
APC 3.5 (f)
to
APC 3.5 (f) (HP 8340B
only)
..................
HP P/N 5061-5311
APC 3.5 (f)
-
Type
N
(m) (HP 8341 B
only)
.................
HP P/N 1250-1744
Dual
Banana to BNC (f)
................................
HP P/N 1251-2277
BNC (f)
-
Clip Lead
.................................
HP P/N 8120-1292
Procedure
MODULATOR OFFSET
1.
Connect the DVM
to
A26TP3 (MOD
LVL).
Preset A26R88 (MO) fully
clockwise (Figure 5-53). Turn
the DUT's LINE switch ON
and allow
30 minutes warm
up.
2. Press
[INSTR PRESET]
on the
DUT.
Press
[CW] [8] [GHz].
Press
[SHIFT]
[METER]
to bypass
the ALC
circuit and allow direct control of the linear modulator
circuit.
3. Adjust the front panel rotary knob
(RPG)
for
a
DVM
indication of
0.00
V +
3
mV, then note the
indication in the
POWER
dBm display. Adjust
A26R88 (MO) counter-clockwise to decrease the
POWER dBm
indication by
0.2 dB.
LEVELED BIAS
4.
Disconnect the
DVM
and connect the oscilloscope as shown
in
Figure 5-52.
5.
Set the oscilloscope as follows:
DISPLAY
...................................................
CHANNEL
A
CHAN A
.........................................
0.02 V/Div DC COUPLED
TRIGGER
....................................................
EXT. POS.
TIME/Div
.........................................................
5
mS
6.
On the DUT, press
[INSTR PRESET] [START FREQ] [7] [GHz] [STOP FREQ] [1] [3] [.] [5] [GHz].
Press
[SHIFT] [PWR SWP] [-] [2] [0] [dBm].
Press
[SWEEP TIME] [5] [0]
[msec].
Save
this instrument state by pressing
[SAVE]
[2].
7.
The oscilloscope display
should be similar to
Figure 5-54. Adjust
A24R12 (MIN)
so that all points
on the trace are reduced to the lowest possible voltage level
(i.e.,
maximum negative voltage).
5-102
Adjustments
HP 8340B/41B