External Gain; Attenuation Control - Keysight Technologies FieldFox N9912A104 User Manual

SA (Spectrum Analyzer) Mode
SA Mode Settings

External Gain

When using an external amplifier or attenuator, the SA mode trace amplitude
values can be offset to compensate for the effect of the external device. This
effectively moves the reference plane of the SA measurement port out to just
beyond the external device. For example, when using an external preamp with
gain of +10 dB, enter this value for External Gain, and the data trace across the
displayed frequency span will be adjusted down by 10 dB.
When RF Atten is set to Auto, you may see a change in the RF Attenuation
value. This is an attempt to measure the signal at top of screen (the Reference
Level) without overloading the SA first mixer.
How to Set External Gain
— Press Scale/Amptd.
— Then More.
— Then
— Enter a value using the numeric keypad, the
(positive for gain; negative for loss). Values less than 5 dB must be typed
using the numeric keypad. Then press Enter
ExtGain xx dB is shown at the top of the screen.

Attenuation Control

Both the RF Attenuation and Pre Amp functions control the power level into the
SA.
When too much power is present at the RF Input port,
appears on the FieldFox screen. This does not necessarily mean that damage
has occurred, but that the measurement is probably compressed.
When high power levels are present at the RF Input port, internal attenuation
can be switched in to keep the FieldFox receiver from compressing. At
extremely high power levels, use external attenuation to protect the internal
circuitry from being damaged.
The FieldFox can be damaged with too much power.
RF Damage Level: +27 dBm
DC Damage Level: ±50 VDC
The displayed power level is automatically adjusted for RF Attenuation. As the
attenuation value changes, the displayed power level should NOT change.
How to set Attenuation
The default Attenuation setting is 10 dB. This value can be changed from 0 to
31 dB in 1 dB steps.
8- 10
External Gain.
arrows, or the rotary knob
ADC Over Range
Keysight N9912-90001 User's Guide