50 Mhz Frequency Counter, Modulation, Leveling And Frequency Pull Input Connector - Fluke 96000 Series Operator's Manual

96000 Series
Operators Manual
External Reference I/O's are used to lock frequency synthesizers of
two or more instruments (daisy chain). This eliminates offset and
drift of frequency between instruments, allowing, for instance, a
Spectrum Analyzer to accurately tune with respect to the Instrument.
If they were not locked, the Analyzer and Instrument would be likely
to drift off tune and the Analyzer could lose or not see the Instrument
signal.
Instruments locked to the same Reference Frequency in this way
can still exhibit very slight frequency offsets due to synthesizer /
divider errors, and the two output frequencies will not be phase
locked. (See description under Modulation Leveling and Frequency
Pull Input Connector.)
50 MHz Frequency Counter, Modulation, Leveling and Frequency Pull Input
Connector
The 50 MHz Frequency Counter, Modulation, Leveling and Frequency Pull Input
Connector is a BNC connection for applying a multifunction external control
signal to the Instrument. Depending upon the operating settings of the
Instrument, the signal may be tailored for modulation control, leveling control,
frequency control, or Frequency Counter input.
If AM, FM, or Phase Modulation (PM) is in use, this input can be used to connect
an external modulation source. In this case, the input is enabled via the Modulation
Preferences screen and ac or dc coupling can be selected. See Table 3-4 and
Table 3-5 for the input specifications.
If Leveled Sine is in use, this input will accept a dc feedback voltage from either
of these:
1. An external power meter – for external leveling of the signal at the power
To prevent damage to the load when using External Leveling,
ensure that the maximum output level is suitably limited via the
Leveled-Sine Preferences screen.
2. An external phase detector and error amplifier – for phase locking the output
3-26
meter input. The feedback is compared with an internal adjustable reference
voltage at the input of an error amplifier. The Instrument output level adjusts
to minimize the difference. See Table 3-6 for the input specifications.
of the Instrument to that of another Instrument. In this case, this input is a
voltage for controlling Instrument output frequency. Output frequency can be
pulled by up to ±5 ppm, depending on sensitivity setting. In some
instruments, the equivalent feature is called Electronic Frequency Control or
EFC. See Table 3-7 for the input specifications.
Note
 Caution