MAINTENANCE
CALIBRATION ADJUSTMENTS
1. Replace the access screw.
3, Detector Offset Adjustment
This adjustment sets the
detector
offset voltage.
TEST EQUIPMENT
Power Meter and
Sensor
REMARKS
The UUT must be operated at room temperature for
at
least
one
hour with
the
module
plate cover in place before continuing
with
this adjustment procedure.
This
adjustment is normally required only when components in the detector or detector
linearizer circuits have been replaced or when the adjustment has been changed or has
shifted. If the Detector Offset is adjusted, perform
the
AM
Depth adjustment.
CAUTION
This adjustment directly
affects the
output level and should not be adjusted
indiscriminately.
PROCEDURE
The
Detector
Offset adjustment, R144, is adjusted to
provide
a 20-dB change in output
power for a 20-dB change in the LEVEL
DAC with level correction disabled, and while
operating in fixed range.
a. Gain access for this adjustment
by
removing
the instrument bottom cover.
b. Program the UUT to [RCL]
[9][8],
then program the UUT to 350 MHz and
12 dBm.
c. Program the UUT to
[SPCL]
[8][1]
and [SPCL]
[9][1].
These special
functions disable all
level
correction and enable amplitude fixed-range.
d. Remove the
Detector Offset adjustment access screw
from
the
bottom
module plate cover.
e. Zero the
Power Meter.
f. Connect the Power Sensor to
the
UUT RF OUTPUT connector.
g.
Program the UUT to +12 dBm.
h. Note
the Power
Meter reading.
i. Program the UUT for
-8
dBm,
using
the EDIT keys.
j.
Adjust the
Detector
Offset adjustment, R
144,
for a Power Meter reading 20
dB ±0.1 dB below the reading obtained in step h.
4C-7
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