Rohde & Schwarz R&S SMB100B - Automatic Level Control (ALC); Reverse Power Protection

Improving level performance
R&S
®
SMB100B
153User Manual 1178.3711.02 ─ 08
Level Range
Shows the interruption-free range of the level that you can use in the selected mode.
Remote command:
:OUTPut<hw>:AFIXed:RANGe:LOWer? on page 395
:OUTPut<hw>:AFIXed:RANGe:UPPer? on page 395
RF OFF Mode
Determines the state of the step attenuator, when the RF signal is switched off.
The setting is not affected by an instrument preset ([Preset] key or *RST) and the
"Save/Recall" function. It is reset only by factory preset.
"Unchanged"
Freezes the setting of the step attenuator.
Use this mode if a constant VSWR (Voltage Standing Wave Ratio) is
required.
"Full Attenuation"
Switches to the maximum attenuation.
Use this mode for applications that require a high level of noise sup-
pression.
Remote command:
[:SOURce<hw>]:POWer:ATTenuation:RFOFf:MODE on page 493
7.1.2 Reverse power protection
The R&S SMB100B is equipped with a reverse power protection circuit.
The reverse power protection is tripped when the power of signals reflected from the
load or external signals applied to the RF output get too high. A relay opens and inter-
rupts the internal connection to the RF output. This condition is indicated in the status
bar by the "Overload" status message.
Overload
If an "Overload" status message is indicated in the status bar, perform the following:
●
Remove the cause for the overload
●
Press the [RF on/off] key to reset the overload protection
The RF input is activated when the overload protection is reset.
Remote command:
:OUTPut<hw>:PROTection:TRIPped? on page 396
:OUTPut<hw>:PROTection:CLEar on page 396
7.2 Automatic level control (ALC)
The R&S SMB100B is equipped with an automatic level control (ALC) unit to obtain
best RF level accuracy.
Automatic level control (ALC)