Keysight N5221A/22A Service Guide 5-11
Theory of Operation
Synthesized Source Group Operation
A21 Multiplier/Amplifier 26.5 Board (HMA26.5)
In bands 2–15, the synthesized LO input is filtered, amplified, and passed
through to the A22 splitter (4-port only). In bands 16-21, the input is amplified,
doubled, and filtered, then sent to the output.
Together, these signal paths create the full output frequency range of 10 MHz
to 26.5 GHz that is sent to the A22 splitter (4-port only) where the signal is
divided and sent to the A23 and A24 (4-port only) mixer bricks as the LO
signal.
A10 Frequency Reference Board
This assembly provides stable reference frequencies to the rest of the
instrument. A high stability 10 MHz oven-controlled crystal oscillator (OCXO)
normally provides the frequency standard. However, if a 10 MHz external
reference signal is detected at the 10 MHz EXT REF IN port on the rear panel, it
is used as the frequency reference instead.
The 10 MHz reference signal is used to phase lock a 100 MHz VCO. The output
of this VCO is then divided by ten to produce the 10 MHz EXT REF OUT rear
panel signal and also a 10 MHz reference signal for the A12 signal processing
ADC module (SPAM) board. The VCO output is also divided by two to produce
50 MHz reference signals for the A4, A13, and A11 13.5 GHz synthesizer
boards.
Rear-Panel Interconnects
A19 Test Set Motherboard
The A19 test set motherboard serves these functions:
— to act as an interface between the A17 CPU board and the auxiliary rear
panel interconnects.
— to provide ALC signals to the A21 HMA26.5.
— to route control signals to the signal separation group. Refer to
Separation Group Operation” on page 5-16
for more information.
10 MHz REF INPUT
A BNC connector that allows an external frequency reference signal to be used to
phase lock the analyzer for increased frequency accuracy.
The analyzer automatically enables the external frequency reference feature when
a signal is connected to this input. When the signal is removed, the analyzer
automatically switches back to its internal frequency reference.
10 MHz REF OUTPUT
A BNC connector that allows a 10 MHz reference signal, produced by the A10
frequency reference board, to be output for use in phase locking external test
equipment.
Summary of Contents for N5221A
Page 9: ...Contents Keysight N5221A 22A Service Guide 10 ...
Page 10: ...11 Keysight N5221A 22A Service Guide Contents ...
Page 156: ...5 32 Keysight N5221A 22A Service Guide Theory of Operation Power Supply Group Operation 5 ...
Page 264: ...6 108 Keysight N5221A 22A Service Guide Replaceable Parts Replaceable Parts Listings 6 ...