14  N9912A FieldFox User’s Guide  
  Then Internal Temperatures.  
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 
At approximately 73 °C, the FieldFox enters Temperature Control mode by 
reducing display intensity and measurement speed. This should decrease the 
internal temperature which preserves measurement accuracy and maintains the 
long-term reliability of the FieldFox.  
When entering Temperature Control mode, save your instrument state and data 
that you want to keep.  
When the temperature drops to approximately 71°C, normal operating settings 
are restored.  
NOTE  Measurement speed specifications do NOT apply in Temperature Control Mode. 
High-Temp Shutdown 
In extreme situations, Temperature Control mode may not stop an increase in 
the FieldFox internal temperature.  At approximately 75°C, High-Temperature 
Shutdown will engage and turn OFF the FieldFox.  
Just prior to shutdown, the FieldFox will display a warning of imminent shut 
down.  
Avoid Overpowering the FieldFox 
The FieldFox can be damaged with too much power or voltage applied. 
Exceeding the maximum RF power levels shown below will cause an ADC Over 
Range message to appear on the screen.  
Maximum Input Voltages and Power: 
  RF OUT Connector: ±50 VDC, +23 dBm RF 
  RF IN: ±50 VDC, +27 dBm RF 
  DC Input: 19 VDC, 4 ADC 
Learn more about Maximum power and voltages in the FieldFox Data Sheet on 
page 204. 
 
NOTE  Very often, coaxial cables and antennas build up a static charge, which, if 
allowed to discharge by connecting to the FieldFox, may damage the instrument 
input circuitry. To avoid such damage, it is recommended to dissipate any static 
charges by temporarily attaching a short to the cable or antenna prior to 
attaching to the FieldFox.