5-15. ALC ADJUSTMENTS (Cont’dJ
20. If all power meter indications are within the test limit, check at power levels from —20 dBin to
+lOdBm 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 [INSTRPRESET].
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 OUT RF output. Connect a BNC Tee at the detector
output. Connect a BNC cable from one output of the Tee to the OUT’s LEVELING EXT INPUT.
Connect another BNC cable from the BNC Tee to a OVM. Set the OVM 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 [INSTRPRESET]. 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 OVM indication of —31.6
mV ±0.3 inV. Access
Calibration Constant Number 45
by entering the following: [SHIFT][GHz][4] [5] [Hz] [SHIFT][MHz][1] [2] [Hz] [SHIFT][kHz][2]
[2] [Hz].
23. Press [POWERLEVEL] and enter [0] [dBm].
Adjust calibration constant
Number 48 for a OVM
indication of —1.00 volts
±
0.01 volts. Access Calibration Constant Number 48 by entering the
following: [SHIFT][GHz] [4] [8] [Hz] [SHIFT][ENTRYOFF].
24. Press [POWERLEVEL] 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 t6 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 OVM
indications are within ±1%.
26. Connect a positive XtaI 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 inV.
5-96
Adjustments
HP 8340B/41B