Sec.  80.859   Main power supply.

   (a) The main power supply must simultaneously energize the radiotelephone
   transmitter at its required antenna power and the required receivers. Under
   this load condition the voltage of the main power supply at the
   radiotelephone input terminals must not deviate from its rated potential by
   more than 10 percent on ships completed on or after July 1, 1941, nor by
   more than 15 percent on ships completed before that date.

   (b) Means must be provided for charging any batteries used as a main power
   supply. A continuous indication of the rate and polarity of the charging
   current must be provided during charging of the batteries.