Keysight N9927-90001 User’s Guide                31
Preparing for Initial Use of Your New FieldFox
FieldFox High Temperature Protection
— The temperature at which the following events occur is the average of the 
RF1, RF2, SB1, SB2 temperatures. These temperatures come from internal 
sensors embedded within FieldFox.
Temperature Control Mode
The FieldFox’s internal temperature control preserves measurement accuracy 
and maintains the long-term reliability of the FieldFox. See also, “High-Temp 
Shutdown Warning (RTSA Mode Only)” on page 33. 
Entering Temperature Control Mode
At an average internal temperature of above approximately 64°C, the FieldFox 
enters Temperature Control mode by reducing display intensity. This should 
decrease the internal temperature which preserves measurement accuracy and 
maintains the long-term reliability of the FieldFox. Refer to Figure 2-1.
In addition, duty cycling is enabled when the internal average temperature of 
the FieldFox reaches the duty cycling threshold of above ~64°C. All 
applications (except RTSA): Power for internal circuitry is turned off between 
sweeps and delaying occurs for the next sweep. In RTSA mode, power is only 
turned off, if the FieldFox is in Single Sweep or Hold.
All applications (including RTSA): Display dims to 40% at ~64°C. 
For all modes, except RTSA mode, you will see the following messages 
displayed for ~3 seconds: 
"Automatic Meas Duty Cycling activated for thermal 
management"
Later if the temperatures are reduced:
"Temperatures reduced, ending Automatic Meas Duty Cycling"
For RTSA mode (where duty cycling is not possible), you will see the following 
messages displayed for ~3 seconds: 
"Entering Auto Protect mode for thermal management"
Later if the temperatures are reduced:
"Temperatures reduced, exiting Automatic Protect Mode"
Entering Auto Protect (Maximum) Threshold Temperature Mode
At above approximately 75°C, the FieldFox enters (Maximum) Auto Protect 
temperature control mode by displaying the "Entering Auto Protect mode...". 
See also Table 2-1 on page 34.
When you enter the Auto Protect (Maximum) Threshold, the following message 
is displayed:
Measurement speed specifications do NOT apply in Temperature Control 
Mode.