Keysight Technologies N5247B, Service Manual

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5-8 Keysight N5247B Service Guide
Theory of Operation
Network Analyzer System Operation
5-
For Version 6 and below synthesizers , analyzers with DSP version 4.0, the
comparison (mix) produces the 7.606 MHz (or 2.535 MHz at frequencies below
53 MHz) IF signal. For analyzers with DSP version 5.0, the comparison (mix)
produces the 7.438 MHz (or 0.826 MHz at frequencies below 53 MHz) IF signal.
For Version 7 synthesizers , the comparison (mix) produces the 7.438 MHz (or
0.826 MHz at frequencies below 53 MHz) IF signal.
LO Behavior with LFE (Low Frequency Extension):
On the direct digital synthesizer (DDS) assembly (Version 7 synthesizers) or on
the synthesizer board (Version 6 synthesizers and below), there is a LFE output
that is limited by the L-C filter and by the 250 MHz low pass filter.
Below 20 MHz, the LFE is signal is directly converted. Exceptions are shown in
Figure 5-15 on page 5-45 . See also, “A70 4-Port and A75 2-Port Low
Frequency Extension (LFE) Board” on page 5-32 .
The incident signal output power is leveled by an internal automatic leveling
control (ALC) circuit.
For version 6 synthesizers, the maximum output power level of the network
analyzer at the test ports is shown in the “N5247B– (900 Hz) 10 MHz to 67
GHz -with synthesizer revision 6 or earlier”, available online at:
https://www.keysight.com/upload/cmc_upload/All/N5247B_Synth6.pdf
For version 7 synthesizers, the maximum output power level of the network
analyzer at the test ports is shown in the “N5247B– (900 Hz) 10 MHz to
67 GHz – Data Sheet and Technical Specifications”, available online at:
https://www.keysight.com/us/en/assets/9018-04526/data-sheets/9018-04
526.pdf (N5247-90029).
Refer to “Synthesized Source Group Operation” on page 5-10 .
Signal Separation Group
Each of the incident signals from the source group is separated into a reference
path and a test path. The reference signal is transmitted to the receiver group.
The test signal is transmitted through—and reflected from—the DUT and is then
transmitted to the receiver group.
The signal separation group includes:
— RF path switching to allow forward and reverse measurements
— external connections for the DUT (configurable test set)
— optional step attenuators in the source and receiver paths
— optional mechanical switches
— optional bias tees
Refer to
“Signal Separation Group Operation” on page 5-46 .