A21 Multiplier/Amplifier 26.5 Board (Hma26.5); A10 Frequency Reference Board - Agilent Technologies N5242A Service Manual

PNA Series Microwave Network Analyzers
N5242A
with an external test set. This output is terminated with a 50-ohm load on the A8 26.5 GHz
source.
The companion signal, EXT TEST SET DRIVE LO, is output from the A23 mixer brick.
Refer to "A23 and A24 Mixer Bricks" on page

A21 Multiplier/Amplifier 26.5 Board (HMA26.5)

In bands 2–28, the synthesized LO input is filtered, amplified, and passed through to the
A22 splitter (4-port only). In bands 29–36, the input is amplified, doubled, and filtered,
then sent to the output.
Together, these signal paths create the full output frequency range of 12.5 MHz to
26.508 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
10 MHz REF INPUT
10 MHz REF OUTPUT
Service Guide N5242-90001
5-21.
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.
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.
Theory of Operation
Synthesized Source Group Operation
5-11