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Chapter 9
287
EXT REF IN
This connector allows you to input an external reference. The reference frequency is
selected using the Ext Ref In field on the INSTRUMENT CONFIGURE screen.
Operating Considerations
Input frequency = 1, 2, 5, 10, or 15 MHz; 1x, 2x, 4x, 8x, or 16x chip
Input level >0.15 V rms
Input impedance approximately 50Ω.
When a valid signal is applied to the EXT REF IN port, the Test Set automatically
switches from internal to external reference if the Ref Select field is set to Auto.
This signal is used as a reference for, and directly affects, these functions:
RF Generator Frequency (including the Tracking Generator)
RF Frequency Counter
AF Frequency Counter
RF Analyzer Tune Frequency
Spectrum Analyzer Center Frequency
CDMA Generator Frequency
CDMA Analyzer Frequency
AF generators 1 and 2 are not affected using an external reference; they use their own
reference.
NOTE The reference output frequency is always 10 MHz, independent of the selected input
reference frequency.
Electrostatic discharges to the EXT REF IN port of 0.5 kV or above may cause
degradation of performance requiring operator intervention.