32                                       Keysight N9927-90001 User’s Guide
Preparing for Initial Use of Your New FieldFox
Avoid Overpowering the FieldFox
Summary of FieldFox Average Internal Temperature Protection 
Behavior
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.
Table 2-1  Summary of FieldFox Temperature Protection 
Threshold  Average Internal 
Temperature
Description of Behavior
Duty cycling ~64°C Duty cycling is enabled when the internal average temperature of the 
FieldFox reaches the duty cycling threshold of ~64°C. Power is turned 
off between sweeps and delaying occurs for the next sweep. 
In RTSA mode power is only turned off in Single Sweep or Hold. This 
enables you to control your instrument’s temperature when you don’t 
need to make a measurement by using the "Run/Hold" hardkey to 
pause the sweep. 
All applications (including RTSA): Display dims to 40% at ~64°C. 
Maximum Protect (Initial) ~75°C When temperature reaches the maximum protection threshold 
(~75°C) some applications take additional measures. 
1 degree below shutdown 
(RTSA Mode Only)
~77°C RTSA Shutdown Warning (~77°C) — (Top "WARNING..." message 
displays for 9 sec). Red text at bottom of display remains on until 
internal temperature returns to ~75.5°C. Refer to Figure 2-3 on 
page 31.
Shutdown  ~78°C Instrument shuts down.
Exit Duty Cycle ~62.5°C The temperature required to come out of the duty cycle threshold. 
Maximum Input Voltages and Power:
— RF IN/OUT Connectors: ±50 VDC, +27 dBm RF
— DC Input: -19 to 19 VDC, 60 Watts maximum when charging battery
Learn more about Maximum power and voltages in the FieldFox Data 
Sheet.
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.