Rf Signal Path - Tait TM9100 Service Manual

12.4

RF Signal Path

The RF signal path extends from the output of the frequency synthesizer to
Introduction
the LPF. This section of circuitry will require investigation either following
certain checks in
"Biasing of PA Driver and PAs"
into nine tasks grouped as follows:
The initial signal path includes the exciter and PA driver. The directional
coupler, PIN switch, and LPF make up the final signal path.
The measurement points for diagnosing faults in the signal path are
summarized in
Figure 12.14 Measurement points for diagnosing faults in the RF signal path
SIGNAL TYPES
RF
ANALOG
TEST
CAPACITOR
Ω
50 TEST
LEAD TO
TEST SET
DIREC-
TIONAL
COUPLER
RECEIVER
TEST
CAPACITOR
Ω
50 TEST
LEAD TO
TEST SET
RF CON-
NECTOR
354 Transmitter Fault Finding (25W Radios)
"Transmitter RF Power"
Task 25 to Task 28: initial RF signal path
Task 29 and Task 30: directional coupler
Task 31 and Task 32: PIN switch
Task 33: LPF
Figure 12.14.
PAs
L314
GATES OF
Q309, Q310
DRAIN OF Q306
PIN
SWITCH
LPF
or if the biasing checks of
reveal no fault. The procedure is divided
EXCITER
OUTPUT
DRIVER
C301
PA DRIVER
OUTPUT AT
© Tait Electronics Limited August 2005
SYNTHESIZER
OUTPUT
SYN TX LO
EXCITER
C300
BUFFER
OUTPUT
AT C313
FRE-
QUENCY
SYNTHE-
SIZER
TM9100 Service Manual