10-18 Chapter 10
Service Key Menus and Error Messages
Service Key Menus
SM4 Automatically attempts to determine new pretune values
when the instrument encounters phase lock problems (for
example, “harmonic skip”). With , the
frequencies and voltages do not change, like when they are
attempting to determine new pretune values, so
troubleshooting the phase-locked loop circuits is more
convenient. This function may also be turned off to avoid
pretune calibration errors in applications where there is a
limited frequency response in the R (reference) channel. For
example, in a high power test application, using band limited
filters for R channel phase locking.
N/A Displays a phase lock sequence at the beginning of each band.
This sequence normally occurs very rapidly, making it
difficult to troubleshoot phase lock problems. Switching this
mode ON slows the process down, allowing you to inspect the
steps of the phase lock sequence (pretune, acquire, and track)
by pausing at each step. The steps are indicated on the
display, along with the channel (C1 or C2) and band number
(B1 through B13).
This mode can be used with PLL PAUSE to halt the process
at any step. It can also be used with the analog bus counter.
N/A
Used only with PLL DIAG mode. indicates that it
will continuously cycle through all steps of the phase lock
sequence. holds it at any step of interest. This
mode is useful for troubleshooting phase-locked loop
problems.
N/A Provides access to the rest of the service modes keys.
SM5 Toggles the sampler correction routine ON, for normal
operation, or OFF, for diagnosis or adjustment purposes.
N/A Normal operating condition and works in conjunction with IF
GAIN ON and OFF. The A10 assembly includes a switchable
attenuator section and an amplifier that amplifies low-level
4 kHz IF signals (for A and B inputs only). This mode allows
the A10 IF section to automatically determine if the
attenuator should be switched in or out. The switch occurs
when the A or B input signal is approximately −30 dBm.
N/A Locks out the A10 IF attenuator sections for checking the
A10 IF gain amplifier circuits, regardless of the amplitude of
the A or B IF signal. Switches out both the A and B
attenuation circuits; they cannot be switched independently.
Be aware that input signal levels above −30 dBm at the
sampler input will saturate the ADC and cause measurement
errors.
Table 10-11 Service Modes Menu Keys
Key GPIB
Mnemonic
Description
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