Understanding power supply requirements

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I have a basic question about power supply requirements for typical transceivers. I'm looking at the specs for a Kenwood TM-V71A, which is a 50W mobile transceiver.



I figured that a 50W transceiver running on a 12V(-ish) power supply would pull around 4A max, but the specs for this radio show a "maximum current drain" of around 13A. How does that work?






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    I have a basic question about power supply requirements for typical transceivers. I'm looking at the specs for a Kenwood TM-V71A, which is a 50W mobile transceiver.



    I figured that a 50W transceiver running on a 12V(-ish) power supply would pull around 4A max, but the specs for this radio show a "maximum current drain" of around 13A. How does that work?






    dc-power







    share|improve this question























      up vote
      2
      down vote

      favorite









      up vote
      2
      down vote

      favorite











      I have a basic question about power supply requirements for typical transceivers. I'm looking at the specs for a Kenwood TM-V71A, which is a 50W mobile transceiver.



      I figured that a 50W transceiver running on a 12V(-ish) power supply would pull around 4A max, but the specs for this radio show a "maximum current drain" of around 13A. How does that work?






      dc-power







      share|improve this question













      I have a basic question about power supply requirements for typical transceivers. I'm looking at the specs for a Kenwood TM-V71A, which is a 50W mobile transceiver.



      I figured that a 50W transceiver running on a 12V(-ish) power supply would pull around 4A max, but the specs for this radio show a "maximum current drain" of around 13A. How does that work?






      dc-power




      dc-power






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      asked 3 hours ago









      larsks

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          A 50W transmitter is one that can create 50 watts of RF output. The RF amplifier is never 100% efficient, so the input power requirements will always be higher than the output power.



          Furthermore, the maximum current drain accounts for startup transients and other peaks in excess of the average current drain.






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            A 50W transmitter is one that can create 50 watts of RF output. The RF amplifier is never 100% efficient, so the input power requirements will always be higher than the output power.



            Furthermore, the maximum current drain accounts for startup transients and other peaks in excess of the average current drain.






            share|improve this answer
























              up vote
              3
              down vote













              A 50W transmitter is one that can create 50 watts of RF output. The RF amplifier is never 100% efficient, so the input power requirements will always be higher than the output power.



              Furthermore, the maximum current drain accounts for startup transients and other peaks in excess of the average current drain.






              share|improve this answer






















                up vote
                3
                down vote










                up vote
                3
                down vote









                A 50W transmitter is one that can create 50 watts of RF output. The RF amplifier is never 100% efficient, so the input power requirements will always be higher than the output power.



                Furthermore, the maximum current drain accounts for startup transients and other peaks in excess of the average current drain.






                share|improve this answer












                A 50W transmitter is one that can create 50 watts of RF output. The RF amplifier is never 100% efficient, so the input power requirements will always be higher than the output power.



                Furthermore, the maximum current drain accounts for startup transients and other peaks in excess of the average current drain.







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                share|improve this answer










                answered 1 hour ago









                Phil Frost - W8II

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