Sec. 80.253  Technical requirements for main transmitter.

    (a) The following table gives the operating carrier frequency, 
emission, modulation and average ship station antenna power requirements 
for the main transmitter.

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                                  Frequency                                                     
                
                                  tolerance                       Percentage      Modulation    
   Power into   
  Operating frequency (kHz)  -------------------    Class of      modulation    frequency for   
  average ship  
                              Parts \1\             emission    for amplitude     amplitude     
 station antenna
                              in 10 \6\  Hz \2\                   modulation      modulation    
                
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500 kHz.....................    1,000      20    A2A and A2B    Not less than  At least 1       
Not less than   
                                                  or H2A and     70; not more   frequency       
 200 watts.     
                                                  H2B.           than 100.      between 300     
                
                                                                                and 1250        
                
                                                                                Hertz, except   
                
                                                                                for             
                
                                                                                transmittal     
                
                                                                                installed       
                
                                                                                after July 1,   
                
                                                                                1951, at least  
                
                                                                                1 frequency     
                
                                                                                between 450     
                
                                                                                and 1250 Hertz. 
                
    Do......................    1,000      20    A1A or J2A...  .............  ...............  
Not less than   
                                                                                                
 160 watts.     
410 and 2 working               1,000      20    A2A and A3N    Not less than  At least 1       
Not less than   
 frequencies in the band 415                      or H2A and     70; not more   frequency       
 200 watts.     
 to 525.                                          H3N.           than 100.      between 300     
                
                                                                                and 1250        
                
                                                                                Hertz, except   
                
                                                                                for             
                
                                                                                transmitters    
                
                                                                                installed       
                
                                                                                after July 1,   
                
                                                                                1951, at least  
                
                                                                                1 frequency     
                
                                                                                between 450     
                
                                                                                and 1250 Hertz. 
                
    Do......................    1,000      20    A1A and N0N    .............  ...............  
Not less than   
                                                  or J2A and                                    
 160 watts.     
                                                  J3N.                                          
                
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\1\ For equipment type accepted or type approved before November 30, 1977.                      
                
\2\ For equipment type accepted or type approval after November 29, 1977.                       
                

    (b) A main transmitter must operate at its required antenna power 
when adjusted to any required operating frequency and energized by the 
main power supply of the ship station or by an equivalent power supply.
    (c) A main transmitter must be equipped to measure (1) antenna 
current, (2) transmitter power supply voltages, and (3) anode or 
collector current(s).
    (d) The antenna power must be determined at the operating carrier 
frequency by the product of the antenna resistance and the square of the 
average antenna current, both measured at the same point in the antenna 
circuit at approximately ground potential.
    (e) A main transmitter producing more than 250 watts output power 
must have the output power reduced to not more than 150 watts when used 
for telegraphy. In stations where a separate telegraph transmitter 
operable on the same frequencies as the main transmitter with an output 
power of less than 250 watts, is installed, the power reduction 
requirement does not apply. Such separate transmitters must not obtain 
power from the emergency power supply.