howeverthemountingterminalsforR13are
always in place.
The voltage across R13 should be 26-32
volts peak-to-peak.
Adjust the horizontal vernier of the oscil-
loscope so that one full RF cycle occupies
a certain number of divisions on the oscil-
loscope. For example: 7.2 divisions. Each
division is then 50 degrees (there are 360
degrees in one cycle).
Use the external trigger input of the oscil-
loscope and connect it to J4 or R25 on the
RF Oscillator.
Adjust thescope triggering, then verifyits
operation by disconnecting the external
trigger input. The oscilloscope should lose
sync as this is done.
Increase the vertical sensitivity of the os-
cilloscope by a step or two. This will cause
the trace to go off scale.
Figure C-2. PA Transistor Identification
and Controls and Indicators (Viewed from Component Side of Board)
1thru8 PACurrent
Limiting
Fuses
These fuses protect
other circuitry in the
transmitter should a
portion of a PA
module fail. As a
result of the fusing
scheme used in the
transmitter, sections
of a power amplifier
may fail and still
allow the remaining
sections of the
power amplifier to
operate properly.
CAUTION
THESE FUSES ARE SPECIAL RECTIFIER
TYPE FUSES ESPECIALLY DESIGNED TO
PROTECT RECTIFIERS AND TRANSIS-
TORS. USE OF REGULAR GLASS FUSES
DEFEATS THE PROTECTION AND CAN RE-
SULT IN DESTRUCTION OF THE GLASS
CASE - POSSIBLY RESULTING IN PERSON-
NELINJURYFROMFLYINGGLASSOR
FROM GLASS PARTICLES THROWN INTO
THE TRANSMITTER INTERIOR.
CAUTION
THE RECTIFIER TYPE FUSE IS FASTER
ACTING THAN THE REGULAR FAST ACT-
INGFUSESANDSOISUSEDTOPREVENT
CASCADING FAILURES. A PA FAILURE
MAY OCCUR WITHOUT UNDUE STRESS
ONTHE MODULATOR. USE OF THE GLASS
TYPE FUSES DEFEATS THIS PROTECTION
ANDWILLVOIDTHEWARRANTY.
Table C-1. PA Module, Controls &
Indicators
Rev. AF: 06-21-2002 888-2314-001 C-3
WARNING: Disconnect primary power prior to servicing.
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