Agilent Technologies FieldFox MW N9913A, Service Manual, Page: 75 / 156

N9927-90003 5-25
FieldFox Analyzer Theory of Operation
Temperature Related Information
Power Meter Mode
All measurement circuitry is switched to the low power state during PM (power meter) mode. This is the
mode with the lowest power dissipation.
The analyzer has no power output capability in this mode. The analyzer essentially functions as a display
for a USB power sensor.
Temperature Related Information
Five temperature sensors are in the analyzer: two on the A4 RF board, two on the A5 System board, and
one in the battery pack.
• RF1—on the A4 RF board
• RF2—on the A4 RF board
• SB1—on the A5 System board
• SB2—on the A5 System board
• Battery pack—inside the battery pack
The battery pack has its own internal temperature sensor. The battery pack will shut itself down in the
case of extreme temperatures.
See Chapter 8 for instructions on viewing temperature readings.
See the FieldFox Analyzer User’s Guide (Part Number N9927-90001), “FieldFox High-Temperature
Protection” section, for information about operation at high temperature.
During normal operation, as each SA measurement is taken, the current RF2 temperature reading is
compared tot he temperature stored for the Frequency Response adjustment. A delta temperature is
calculated. Each SA measurement is adjusted to compensate for the delta temperature.
The internal temperature of the unit is critical when executing the TME based software for tests and
adjustments. See the TME help for detailed information.
Under typical bench top (indoor) conditions, the internal temperature of the unit will be about 20
°
C
above ambient once the internal temperature has stabilized. It will typically take 60 to 90 minutes for the
internal temperature to stabilize when a “cold” unit is turned on.