HP 8340B Manual page 295

5-15.
ALC ADJUSTMENTS (Cont'd)
20.
If
all
power meter indications are within
the
test
limit, check at power levels from —20 dBm to
+10dBm in 5
dB steps.
NOTE
If adjustments of the calibration
constants were made in
this procedure,
the data thus stored
in the "working memory area" should
be copied to
the "protected memory area" by pressing the following key sequence:
[SHIFT] [MHz] [1] [4] [Hz] [SHIFT] [kHz] [5] [3] [4] [9] [Hz]. Wait
for
"CALIBRATION RESTORED" to be displayed
in
the ENTRY DISPLAY and
then press [INSTR
PRESET].
EXTERNAL LEVELING ADJUSTMENTS
NOTE
The negative external Xtal leveling adjustments include two variable
resistor adjustments
(+6
dBV and —60 dBV) and two calibration
con¬
stant adjustments (—30 dBV and 0
dBV).
These adjustments interact
similarly to the
ALC adjustments. See
Figure
5-49 for more information
that may help to reduce the number of iterations required. Note that the
curve rotates about the —30 dBV level.
21. Connect
a
negative Xtal detector to the
DUT RF
output.
Connect
a
BNC
Tee at the detector
output. Connect
a
BNC cable from one
output of the
Tee
to the
DUT's LEVELING EXT INPUT.
Connect another BNC cable from the BNC Tee
to a
DVM. Set the DVM for
a
floating input and
connect
a 0.1
UF capacitor across
its
terminals.
Make
adjustments
in
the following order:
-30
dBV,
0
dBV,
+6
dBV,
0
dBV,
-30
dBV, and
-60
dBv.
22. Press
[INSTR PRESET].
Press
[CW] and enter [4] [.] [5] [GHz].
Press
[XTAL]
leveling.
The
ENTRY DISPLAY
should indicate ATN:
0 dB, REF
-30.00
dBV. Adjust calibration constant
Number 45
for
a
DVM
indication of —31.6 mV
±
0.3 mV. Access Calibration Constant Number 45
by entering the following:
[SHIFT] [GHz] [4] [5] [Hz] [SHIFT] [MHz] [1] [2] [Hz] [SHIFT] [kHz] [2]
12] [Hz].
23. Press
[POWER LEVEL]
and enter
[0] [dBm]. Adjust calibration constant Number 48 for
a
DVM
indication of —1.00
volts ±0.01
volts.
Access
Calibration
Constant Number 48 by entering the
following:
[SHIFT] [GHz] [4] [8] [Hz] [SHIFT] [ENTRY OFF].
24. Press
[POWER LEVEL]
and enter
[6]
[dBm]. The ENTRY DISPLAY REF
level should be
+6
dBV.
Adjust A25R88 (EXHI, see Figure 5-46) for
a
DVM
indication of -2.00 volts
±0,02
volts. The
+6dB
adjustment
will
affect the
0 dBV
level
as well.
To minimize the number of iterations, over
adjust the
+6 dBV
level,
then when the
0 dBV
level is adjusted, the
+6 dBV
level will be close. For
example,
if
the
+6 dBV
indication is 0.1V low, adjust for 0.15V high.
25. Press
[XTAL] and enter
[-]
[6] [0] [dBm].
Adjust A25R80 (EX-)
for
a
DVM
Indication of
-1.000
mV ±0.01
mV.
Repeat
all
negative external leveling adjustments,
in the order given, until all
DVM
indications are within
±1%.
26. Connect
a
positive Xtal detector in place of the negative Xtal detector. Press [•»•] twice
to set
the
RF attenuator set to 20 dB and the REF set to
-60
dBV, adjust A25R84
(EX+)
for +1.000
mV
±0.01
mV.
5-96
Adjustments
HP 8340B/41B