Sec. 80.911  VHF transmitter.

    (a) The transmitter must be capable of transmission of G3E emission 
on 156.800 MHz, 156.300 MHz, and on the ship-to-shore working 
frequencies necessary to communicate with public coast stations serving 
the area in which the vessel is navigated.
    (b) The transmitter must be adjusted so that the transmission of 
speech normally produces peak modulation within the limits 75 percent 
and 100 percent.
    (c) The transmitter must be type accepted to transmit between 20 
watts and 25 watts, on each of the frequencies 156.300 MHz, 156.800 MHz 
and on ship-to-shore public correspondence channels, into 50 ohms 
effective resistance when operated with a primary supply voltage of 13.6 
volts DC.
    (d) When an individual demonstration of the capability of the 
transmitter is necessary the output power requirements prescribed in 
this paragraph must be met as follows:
    (1) Measurements of primary supply voltage and transmitter output 
power must be made with the equipment drawing energy only from ship's 
battery;
    (2) The primary supply voltage, measured at the power input 
terminals to the transmitter, and the output

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power of the transmitter, terminated in a matching artificial load, must 
be measured at the end of 10 minutes of continuous operation of the 
transmitter at its full power output.
    (3) The primary supply voltage must not be less than 11.5 volts.
    (4) The transmitter output power must be not less than 15 watts.
    (5) For primary supply voltages, measured in accordance with the 
procedures of this paragraph, greater than 11.5 volts, but less than 
12.6 volts, the required transmitter output power shall be equal to or 
greater than the value calculated from the formula

          P=4.375 (V)-35.313

where V equals the measured primary voltage and P is the calculated 
output power in watts.''
[ 51 FR 31213 , Sept. 2, 1986, as amended at  54 FR 40059 , Sept. 29, 1989]