Sec. 80.806  Requirements of main installation.

    All main radiotelegraph installations must meet the following 
requirements:
    (a) The main antenna must be installed and protected to ensure 
proper operation of the station. Effective October 14, 1986, the main 
antenna energized by the main transmitter on the frequency 500 kHz must 
produce at one nautical mile a minimum field strength of thirty (30) 
millivolts per meter. If the main antenna is suspended between masts or 
other supports liable to whipping, a safety link must be installed 
which, under heavy stress, will reduce breakage of the antenna, the 
halyards, or any other antenna-supporting elements.
    (b) The main transmitter must be capable of meeting the requirements 
of Sec. 80.253.
    (c) The main receiver must efficiently receive A1A and A2A emission 
on all frequencies within the bands 100-200 kHz and 405-535 kHz. It must 
have headphones capable of effective operation. The main receiver must 
have sufficient sensitivity to effectively operate headphones or a 
loudspeaker when the receiver input is 50 microvolts.
    (d) The main power supply must simultaneously (1) energize the main 
transmitter at its required antenna power, and the main receiver, (2) 
charge at any required rate all batteries forming part of the 
radiotelegraph station, and (3) charge the main power supply for this 
purpose at all times including times of inspection. Under this load 
condition the voltage of the main power supply at the radio room 
terminals must not deviate from its rated value by more than 10 percent 
on vessels completed on or after July 1, 1941, nor by more than 15 
percent on vessels completed before that date. While at sea, batteries 
forming part of the main installation must be fully charged daily.
    (e) To measure voltage(s) of the main power supply at its radio room 
terminals, voltmeter(s) must be permanently installed in the 
radiotelegraph operating room.
    (f) The main installation must be provided with a device permitting 
changeover from transmission to reception and vice versa without manual 
switching.
    (g) The main installation must be capable of being quickly connected 
with and tuned to the main antenna and the reserve antenna if one is 
installed.