10 000 WATT FM BROADCAST TRANSMITTER
FM10
Page 5-3
01 October 2002
Table 5-1 PA Failures Versus RF Output
DISABLED POWER AMPLIFIERS POWER REDUCTION NOMINAL
AND/OR RELATIVE TO RF CARRIER
RF POWER MODULES 10 000 WATTS OUTPUT
One Power Amplifier -0.25dB 9450 Watts
Two Power Amplifiers -0.50dB 8900 Watts
Three Power Amplifiers -0.75dB 8400 Watts
One RF Power Amplifier Module -1.60dB 6900 Watts
Two RF Power Amplifier Modules -3.50dB 4450 Watts
5.4.4 STRESS CURRENT PROTECTION:
Every precaution should be taken to ensure the static
sensitive semiconductor devices are protected from
unnecessary stress current. This is achieved by
ensuring:
- electrical connections are not broken while
current is flowing in the circuit.
- voltages are not present on external control/
monitoring circuits when they are connected.
OPERATION WITH DEFECTIVE OR MISSING
RF POWER AMPLIFIER MODULES:
5.5
It is permissible to operate the transmitter
with a defective or missing RF power amplifier
module, provided the following
precautions/procedures are observed:
5.5.1 If an RF power amplifier module has one or
more defective power amplifiers, as indicated by the
control/monitor panel's PA FAIL ALARM
lamp, but it
is still contributing to the transmitter's RF output; it
may be left on. A reduction in carrier level is the
only consequence. Refer to table 5-1 to determine the
reduction in forward power that can be expected with
different quantities of defective power amplifiers.
Do not attempt to compensate for any RF power
reduction caused by power amplifier assembly
failures by adjusting RF power level controls.
5.5.2 If an RF power amplifier module must be
removed, it must be turned off prior to disengaging
its mating connectors. Follow the instructions
detailed in paragraph 5.7 to turn off a module that
must be removed with the transmitter on-air. At all
other times turn off the switching power supplies by
pressing the RF OFF switch and then switching off the
AC power source. This is accomplished by opening
(turning off) the circuit breaker panel's MAIN POWER
circuit breaker or switching off the AC power source
at the service entrance.
NOTE
When the circuit breaker panel's AC ON lamp is on,
AC power is being applied to the power transformer
and the switching power supplies are capable of
producing a high current positive voltage.
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