HP 8340B Manual page 300

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 for
a
DVM
indication of
0.00 volts, then note the
POWER
dBm
display reading. Adjust
A26R88 (MO) counter-clockwise
until
the
POWER dBm
reading indicates
a
peak of output
power.
If
the output
power cannot
be peaked,
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
Change
14
HP 8340B/41B