HP 4262A - Page 113

Section V Model 4262A
Paragraph 5-22
ADJUSTMENT
5-22. A12 BOARD OFFSET ADJUSTMENT.
PURPOSE:
This
adjustment
eliminates
any
residual
dc
offset
voltage
from
range
resistor
ampli-
fier
to
maximize
accuracy
of
measurement.
Tomz
___________________
—
BNC_To
ALLIGATOR
CLIP
CABLE
it
Seurce
—0)——
mm——————————
Tl‘o
Chassis
OSCILLOSCOPE
e
——
e
——
e
———
o300
OHog0
C
U
Figure
5-3.
A12
Board
Offset
Adjustment.
EQUIPMENT:
Oscilloscope
.
.............
HP
180C/w1801A/w1821A
(Use 10:1 probe)
PROCEDURE:
a.
Connect
BNC
to
dual
alligator
clip
cable
between
oscilloscope
and
transistor
A12Q11*source
on
the
A12
Range
Resistor
Board
Assembly
(See
Figure
5-3).
*(Junction of A12R36 and R41)
b. Set 4262A controls as follows:
DCBIAS.
..
..ot
i,
OFF
SELFTEST............coiiiinininn...
OFF
FUNCTION.
.........cco0itiiiiiinnnnn..
C
CIRCUITMODE.
............ccvuuu...
PRL
LOSS.
...
e
D
TESTSIGNAL
...............covu....
1kHz
LCRRANGE
.....................
MANUAL
(Set
to
100pF
range)
DQRANGE
........................
AUTO
TRIGGER..................
e
INT
c.
Connect
nothing
(open,
co
)
to
UNKNOWN
terminals.
Note
High
terminals
(Hror
and
Hcur)
and
Low
terminals
(Lcur
and
Lpor),
respectively,
must
be connected together.
d. Set oscilloscope control as follows:
VOLTS/DIV
...........cciiunn.
..
0.01v
TIME/DIV.
.............covui....
0.5msec
TRIGGER.
...............
...
........
INT
SWEEPMODE
......................
AUTO
Input...........
...
...
.
GND
5-8