B737
MAINTENANCE MANUAL
EFFECTIVITY
Post ELT STC ST03081AT
23-24-00
PAGE 206
JAN 02/07
(c)
Verify an initial frequency of 406.025 MHz +/- 2 KHz.
NOTE: Allow the unit to run 30 seconds before making the measurement to allow the oscillator
to stabilize.
(12)
Current Draw Test
CAUTION: The following tests involve measurements of the lithium battery pack. Exercise
extreme caution to avoid causing a short circuit condition which will blow the fuses
on the battery pack. It is recommended that only an experienced teachnician
perform these tests.
NOTE: A teat harness (P/N 611-0024) may be ordered from ARTEX Aircraft Supplies at 1-800-
547-8901.
(a) All tests must be performed in an RF screen room or with the ELT in a shielded
container that will substantially attenuate the RF signal.
(b) All “ON” state current measurements must be with the RF outputs loaded with 50
ohms for 5 Watts (either a resistive load or equipment with 50 ohm impedance
padded with 10 dB/ 5 Watt attenuator, i.e. a spectrum analyzer).
NOTE: The ELT may activate (turn “ON”) when the various connections are initially made
during the following current tests. This is normal. Reset the unit to “OFF”, if this
happens, by toggling the ON/OFF switch to ON and back to OFF.
(c)
ARM (“OFF”) State Current Measurement
1) Remove the battery pack as describe in step (3), “Remove Battery Pack”.
2) Disconnect to 2-pin harness.
3) Install the test harness 611-0024 and an in-line ammeter as shown in Figure 1.
4) Ensure the ELT is “OFF”
5)
Measure the current with the ammeter. The measured current should be 0
micro amps (µA) and not more than 6 µA.
(d)
ON State Current Measurement
NOTE: Current draw during this test may exceed 305 Amps during the 406.025 MHz burst.
Ensure the ammeter is set on the appropriate range to accommodate this level of
current.
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