5-38 Keysight N5227B Service Guide
Theory of Operation
Receiver Group Operation
5-
models) are mixed with a synthesized LO signal that is 7.438 MHz higher than
the source incident signal to produce a 7.438 MHz IF signal. This synthesized
LO comes from the A25 HMA26.5 (via the A26 splitter for 4-port models).
At frequencies below 53 MHz, the IF is set to 0.826 MHz.
The analog IF signal is sent to the A24 IF multiplexer board where it is amplified
and then sent to the A16 SPAM board.
The A27 mixer brick sends the EXT TSET DRIVE LO OUT signal to a rear-panel
connector for use with an external test set. This same output connector on the
A28 mixer brick is terminated.
A24 IF Multiplexer Board
This assembly provides pulse modulation capability and routes the IF signal out
through the rear panel connectors for external use and routes external signals
in through rear panel connectors to be included in the signal processing.
In this assembly, on 4-port models, a single reference signal is selected from
R1, R2, R3, and R4 to be sent on to the A16 SPAM. On 2-port models the R1
and R2 reference signals are sent to the A16 SPAM.
The analog IF signals (A, B, C, D, and R for 4-port models and A, B, R1, and R2
for 2-port models) are sent to the A16 SPAM board where they are converted to
digital information.
Rear Panel Interconnects
The A24 IF multiplexer board includes the following rear panel interconnects.
PULSE I/O
A DB-15 female connector. Pin assignments are listed in
.
Table 5-5
PULSE I/O Connector Pin Assignments
DB-15 Female Connector
Pin
Name
Description
1
IFGateAin
IF pulse gate input A (TTL)
2
IFGateBin
IF pulse gate input B (TTL)
3
IFGateCin
IF pulse gate input C (TTL)
4
IFGateDin
IF pulse gate input D (TTL)
5
IFGateRin
IF pulse gate input R (TTL)
