HP 8341b - 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