Anritsu 373XXA - Manual (Page 105)

Receiver Module The Receiver Module consists of the items listed below; refer to Fig-
ure 7-2.
q Quad Sampler/Buffer Amplifier with integrated SRD (step recov-
ery diode)
q Power Amplifier
q A1, LO1 PCB
q A2, LO2 PCB
The Receiver Module is a four channel two stage Sampler/Buffer Am-
plifier and Down Conversion unit. It simultaneously converts the four
22.5 MHz - 40 GHz signals from the Test Set Module into three 2.5
MHz IF signals that are output to the IF Section.
The first stage of the Receiver Module uses harmonic sampling to
down-convert the four 22.5 MHz – 40 GHz output signals from the
Test Set Module down to 89 MHz signals. Any input signals below 270
MHz are passed directly through the four harmonic samplers to the
second stage without down-conversion. The drive signal to each of the
harmonic samplers is a comb of harmonics generated by a step recov-
ery diode (SRD).
The Power Amplifier provides the signal that drives the SRD. The in-
put to the Power Amplifier is the 357 – 536.5 MHz signal from the A1
First Local Oscillator (LO1) PCB. Regardless of the operating fre-
quency, the Power Amplifier is biased on at all times to insure opti-
mum thermal stability.
The second stage of the Receiver Module uses the 25.0 – 272.5 MHz
signal from the A2 Second Local Oscillator (LO2) PCB to down-convert
the 89 MHz signals into four 2.5 MHz IF signals TA, TB, RA, RB (two
test signals and two reference signals). Either the Reference A or the
Reference B IF signal is selected, as is appropriate for Forward/Re-
verse operation. The resultant three 2.5 MHz IF signals (Test A, Test
B, and Reference A/B) are output to the IF Section. A buffered version
of the Reference A/B signal is also fed to the A8 Source Lock/Signal
Separation Control PCB as the Source Lock signal.
The Receiver Module can also select the Reference A IF signal that is
output to the IF Section via the Test A switch path. This IF signal is
used during Line Reflect Line (LRL) Calibrations to ratio the Refer-
ence A and Reference B signals.
ANALOG SUBSYSTEM ASSEMBLIES SYSTEM DESCRIPTION
7-10 373XXA MM