Operation Manual

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that a digital voltmeter (dvm) be used to obtain reference readings for carrier and sideband
power in normal, wide, and narrow alarm. These reference readings can be made with
greater repeatability by using the dvm than by using the analog wattmeter. This is done by
connecting a dvm, set to measure dc voltage, to the detector element output in place of the
normal meter. Improved consistency in dvm readings will result if the dvm input is shunted
with a 1400-W ±1 percent resistor. This resistor presents the same load to the detector
elements as the normal analog meter. If the reference readings are made with the load
resistor in place, all future measurements must be made in this configuration.
3. Measurements taken with built in test equipment (BITE) (i.e., power, DDM, modulation,
etc.) must be verified for accuracy with external test equipment as outlined in this hand-
book. This is to ensure that repeatable results are obtained and maintained in the case of
internal equipment failure and/or replacement of modules that effect BITE measurements.
4. For equipment that uses a maintenance data terminal (MDT), when adjusting the phase of
a signal, the number of degrees adjusted may need to be determined from a reference
index number. This may be accomplished via a table or conversion chart, usually found in
the equipment TI. For this reason, the alternate methods described in the procedures (i.e.,
the addition and removal of line lengths, elbows, etc.) is recommended.
5. The monitor DDM values are the monitor input values as measured with a PIR or the digital
readout values of the monitor or as measured with BITE/MDT. No tolerance is established
for the DDM values. They are used to detect trends such as system or monitor drift.
6. This performance check requires a line entry on Navia Aviation Form “CEGS Monitor Ref-
erence Data”. The reference data line contains the reference data used to perform a mon-
itor performance check. The reference data line can only be updated in accordance with
paragraph 5-7.
c. Test Equipment Required.
1. A portable ILS receiver (PIR).
2. BITE/MDT
3. BIRD wattmeter
4. A dvm.
5. The FA-9438 modulation meter or equivalent.
d. Conditions.
A facility shutdown is required for this check.
e. Detailed Procedure.
1. Preliminary actions.
(a) Refer to Navia Aviation Form “CEGS Monitor Reference Data” for the reference values
specified during the monitor performance check.
(b) Verify that modulation is 40 percent for each tone. (PIR connected to CSB COU test con-
nector on facility front). The facility must be properly phased.
(c) Set up the PIR or equivalent to measure DDM in the carrier feedline and ensure that mod-
ulation equality (0 DDM) exists.
(d) Bypass the equipment monitor(s).
2. Width alarms.
(a) Connect the dvm to the transmitter SBO test connector.
. This voltage represents the nomi-
nal transmitter SBO power in front of the SBO step attenuator
. Measure the dc voltage, note