Anritsu 682XXB - Manual (Page 129)

2. Adjust the Switched Filter Limiter DAC for each
of the frequency bands as follows:
a. At the
$
prompt on the PC display, type:
calterm 145
and press <ENTER>.
b. On the 562 Network Analyzer, set the Resolu-
tion to 0.2 dB and adjust the offset to center
the top of the triangle waveform on the display.
c. Observe the displayed waveform to determine
whether the Shaper Amplifier is being driven
to saturation. This is indicated by a dip in the
top of the triangle waveform (Figure 4-4).
If the displayed waveform indicates there is no
saturation, proceed to step e. If there is a dip
in the waveform, go to step d.
d. On the computer keyboard, use 8, 9, or 0 to
decrement the value of the DAC’s setting until
the top of the triangle waveform starts to be-
come rounded (Shaper Amplifier is no longer
being driven to saturation). Continue decre-
menting until the top of the waveform is 0.3 dB
below this point.
e. Press
Q
on the keyboard to go to the next fre-
quency band.
f. Repeat steps b thru e until the DAC has been
checked and adjusted for all frequency bands.
g. Press
Q
on the keyboard to exit the program.
(The
$
prompt will appear on the screen.)
h. Record step completion on the Test Record.
Shaper DAC
Adjustment For Models 682XXB with Firmware Versions
1.01 to 2.37; Models 683XXB with Firmware
Versions 1.01 to 2.44; Models 682X5B with
Firmware Versions 1.00 to 1.26; and Models
683X5B with Firmware Versions 1.00 to 1.30.
The following steps in the procedure lets you adjust
the Switched Filter Shaper DAC which controls the
gain of the Switched Filter Shaper Amplifier. Each
frequency band will be scanned for the minimum
unleveled power point before adjustment of the
shaper DAC.
1. Set up the 562 Network Analyzer as follows:
a. Press the System Menu key.
b. From the System Menu display, select RESET.
682XXB/683XXB MM 4-19
SWITCHED FILTER
CALIBRATION SHAPER CALIBRATION
Shaper
Amplifier
Saturation
Waveform
0.3 dB
Final
Waveform
After
Adjustment
Shaper
Amplifier
Out of
Sauration
Figure 4-4. Limiter DAC Adjustment
Waveforms
NOTE
The 10 dB attenuator between the
682XXB/683XXB
RF OUTPUT con-
nector and the RF Detector may not
b e r e q u i r e d f o r f r e q u e n c i e s
>20 GHz.