Sec. 80.255  Technical requirements for reserve transmitter.

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

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                                  Frequency                                                     
                
                                  tolerance                       Percentage    Modulation for  
  Power into an 
  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.........................  \3\ 1,000    20    A2A and A2B    Not less than  At least 1       
Not less than 25
                                                  or H2A and     70; not more   frequency       
 watts.         
                                                  H2B.           100.           between 300     
                
                                                                                and 1250 Hertz  
                
                                                                                except for      
                
                                                                                transmitters    
                
                                                                                installed       
                
                                                                                after July 1,   
                
                                                                                1951, at least  
                
                                                                                1 frequency     
                
                                                                                between 450     
                
                                                                                and 1250 Hertz. 
                
410 and 1 working frequency   \3\ 1,000    20    A2A and A3N    ......do.....  ......do.......  
......do        
 in the band 415 to 525.                          or H2A and                                    
                
                                                  H3N.                                          
                
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\1\ For equipment type accepted or type approved before November 30, 1977.                      
                
\2\ For equipment type accepted or type approved after November 29, 1977.                       
                
\3\ Except for reserve transmitters whose use is confined solely to safety communications. Such 
transmitters    
  must maintain a frequency tolerance of 3000 parts in 10.\6\                                   
                

    (b) A reserve transmitter must operate at its required antenna power 
when adjusted to the operating frequency and energized by the reserve 
power supply of the ship station or by an equivalent power supply.
    (c) A reserve transmitter must be equipped to measure antenna 
current.
    (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 gound potential.