Instrument Function
R&S
®
SMB100A
126Operating Manual 1407.0806.32 ─ 13
"Fixed"
When this operating mode is switched on, the attenuator, relays and
amplifier stages are fixed in their current positions to provide level set-
tings without interruption. The resulting variation range is defined and
displayed under "Attenuator Fixed Range".
Note: The function is effective when automatic level control is activated
("ALC State = On").
If the normal variation range is overranged or underranged, level errors
increase considerably and the warning "Level under/overrange"
appears in the info line. The spectral purity of the output signal decrea-
ses with high attenuation.
Remote command:
:OUTPut<hw>:AMODe on page 276
Fixed Range (PEP) In
Displays the level range in which the level is set without interruption for the "Attenuator
Mode fixed" setting.
Remote command:
:OUTPut<hw>:AFIXed:RANGe:UPPer? on page 275
:OUTPut<hw>:AFIXed:RANGe:LOWer? on page 275
RF OFF Mode
Selects the attenuator mode, when the RF signal is switched off.
The setting of the RF OFF mode is not affected by an instrument preset (PRESET key),
*RST and the "Save/Recall" function. This parameter is influenced only by the Factory
Preset.
"Unchanged"
Freezes the setting of the attenuator when RF is switched off. The
attenuator is only activated when RF is switched on.
This setting recommended if a constant VSWR (Voltage Standing Wave
Ratio) is required.
Furthermore, on instruments equipped with a mechanical attenuator, it
provides fast and wear-free operation.
"Full Attenuation"
Sets attenuation to maximum when the RF signal is switched off. This
setting is recommended for applications that require a high level of
noise suppression.
Remote command:
[:SOURce<hw>]:POWer:ATTenuation:RFOFf:MODE on page 340
User Variation
If the level is set using the rotary knob, the step width is defined in the "User Variation"
section.
Variation Active
Activates the user-defined step width used when varying the level value with the rotary
knob.
"ON"
The level value set with the rotary knob is varied using the user-defined
step width which is entered under "Variation Step".
RF Block
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