Anritsu 680 C Series, Maintenance Manual

Page: 128 / 317

NOTE
For the
£
40 GHz models, use the MA2474A
power sensor; for >40 GHz models, use the
MA2475A power sensor.
4. Connect the Power Sensor to the RF OUTPUT of
the 691XXB.
NOTE
Before beginning this calibration proce-
dure, always let the 691XXB warm up for a
minimum of one hour.
AM
Calibration
Procedure The following procedure let you (1) adjust the AM
Calibration DAC to provide the correct amount of
AM in both linear (100%/V sensitivity) and log
(25 dB/V sensitivity) modes of operation for frequen-
cies of
£
2 GHz and >2 GHz, (2) calibrate the AM Me-
ter circuit, and (3) store the results in non-volatile
memory (EEPROM) on the A17 CPU PCB.
NOTE
For those instruments that contain a Down
Converter, the procedure for Linear AM
and Log AM calibration must be performed
twice—once for frequencies
£
2 GHz and
once for frequencies >2 GHz. Upon initial
completion of each procedure, the program
will automatically return you to the start to
repeat the procedure.
1. Set up the Function Generator as follows:
a. Mode: EXT
b. Signal: Square Wave
2. Perform Linear AM calibration as follows:
a. At the
$
prompt on the PC screen, type:
calterm 112
and press <ENTER>.
b. Set the function generator to output 0.00 volts.
When done, press any key on the keyboard to
continue calibration.
c. Now, set the function generator to output
±
0.50 volts. Use the COMPL button on the
function generator to toggle the output be-
tween +0.50 volts and –0.50 volts.
690XXB/691XXB MM 4-31
AM
CALIBRATION CALIBRATION
NOTE
For units with Option 21A installed,
the procedure for Linear AM and
Log AM calibration must be per-
formed twice—once for frequencies
of
£
2.2 GHz and once for frequencies
>2.2 GHz.