S-Is. Alc Adjustments - HP 8340B Manual

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.
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
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]
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
following: [SHIFT][GHz] [4] [8] [Hz] [SHIFT][ENTRYOFF].
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
+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
mV Repeat all negative external leveling adjustments, in the order given, until all OVM
± 0.01 mV.
indications are within ±1%.
26. Connect a positive XtaI detector in place of the negative Xtal detector. Press
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
NOTE
NOTE
0.01 volts. Access Calibration Constant Number 48 by entering the
±
[6] [0] [dBm]. Adjust A25R80 (EX—) for a DVM indication of —1.000
[—]
[5] [GHz]. Press [XTAL]leveling. The
[.]
[~]
0.02 volts. The
±
twice to set the
HP 8340B/41B