Sec. 80.257  Manufacturing requirements for radiotelegraph automatic 
          alarm receiver (auto alarm).

    (a) The auto alarm must consist of:
    (1) A radio receiver capable of receiving emissions of classes A1A, 
A1B, A2A, A2B, H2A, H2B, J2A, and J2B over the frequency range 496 
through 504 kHz.
    (i) The receiver must reject signals +106 dB above one microvolt at 
&177;150 kHz from the center frequency and +88 dB above one 
microvolt at &177;40 kHz from the center frequency.
    (ii) The receiver must respond to signals from 100 microvolts to 1 
volt on the center frequency. There must be less than 6 dB variation in 
sensitivity from 496 kHz through 504 kHz.
    (2) A device capable of selecting the alarm signal specified under 
Sec. 80.259 (a) and (b).
    (3) A minimum of 3 audible alarm units to meet the three location 
installation requirements of Sec. 80.259(g).
    (4) A testing device to determine locally that the auto alarm system 
is operative.
    (b) The auto alarm may be constructed in one or more units but must 
be independent of the ship's regular radio receiving apparatus.
    (c) A telephone jack must be provided to permit reception by a 
telephone receiver.
    (d) Tuning and timing controls must not be accessible from the 
exterior of the device.
    (e) Once set into operation the audible alarms must continue to 
function until switches off in the principal radiotelegraph operating 
room.
    (f) A nonlocking or momentary-throw switch must be provided to 
permit temporary disconnection of the audible alarm on the bridge and in 
the operator's quarters when the auto alarm system is being tested.
    (g) A failure of the auto alarm power supply must activate the 
audible alarms.
    (h) The auto alarm must operate within specifications throughout the 
temperature range 0-50 degrees Celsius at relative humidities as high as 
95%.
    (i) The auto alarm must be protected from excessive currents, power 
supply reversals and voltage variations which could cause damage to any 
component.
    (j) The auto alarm must be capable of operating when subjected to 
vibrations having a frequency between 20 and 30 Hertz and an amplitude 
of 0.76 mm (0.03 inch) in a direction at an angle of 30 to

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45 degrees with the base of the auto alarm.
[ 51 FR 31213 , Sept. 2, 1986, as amended at  58 FR 44952 , Aug. 25, 1993]