Agilent Technologies 8753ES Option 011 Service Manual page 307

SERVICE MODES
Table 10-11 Service Modes Menu Keys
Key
FRACN TUNE on OFF
SRC ADJUST MENU
SOURCE PLL ON off
Chapter 10
GPIB
Mnemonic
Tests the A13 and A14 fractional-N circuits. It allows you to
SM1
directly control and monitor the output frequency of the
fractional-N synthesizer (10 MHz to 60 MHz). Set the
instrument to CW sweep mode and then set FRACN TUNE
ON.
Change frequencies with the front panel keys or knob. The
output of the A14 assembly can be checked at A14J1 HI OUT
(in high band) or A14J2 LO OUT (in low band) with an
oscilloscope, a frequency counter, or a spectrum analyzer.
Signal jumps and changes in shape at 20 MHz and 30 MHz
when tuning up in frequency, and at 29.2 MHz and 15 MHz
when tuning down, are due to switching of the digital divider.
This mode can be used with the SRC TUNE mode as
described in
N/A Accesses the functions that allow you to adjust the source:
SRC TUNE on OFF
the phase lock and source assemblies. Use the entry
controls to set test port output to any frequency from
300 kHz to 6 GHz. When in this mode:
— Set analyzer to CW frequency before pressing
SRC TUNE ON
— Test port output is 1 to 6 MHz above indicated
(entered) frequency.
— Instrument does not attempt to phase lock.
— Residual FM increases.
SRC TUNE FREQ
tune frequency.
ALC ON off
(ALC) on and off.
MAIN PWR DAC
SLOPE DAC
SRC ADJUST DACS
HB FLTR SW on OFF
With this mode switched OFF, the source stays in the pretune
SM3
mode and does not attempt to complete the phase lock
sequence. Also, all phase lock error messages are disabled.
The fractional-N circuits and the receiver operate normally.
Therefore, the instrument sweeps, but the source is being
driven by the pretune DAC in a stair-stepped fashion.
Service Key Menus and Error Messages
Description
Chapter 7 , "Source Troubleshooting."
tests the pretune functions of
.
allows you to change the source
toggles the automatic leveling control
Service Key Menus
10-17