[AMRadio] FCC's AM power


Geoff ars.w5omr at gmail.com
Mon Sep 26 03:55:41 EDT 2016



On 09/26/2016 02:49 AM, Ross Stenberg wrote:
> I know that some my be dismayed by this however there are unscrupulous hams the routinely run homebrew AM  transmitters such as a 4-1000 modulated by a pair of 4-400’s in excess of whatever one thinks is “the legal limit”! There are others that use old broadcast AM transmitters beyond ham limits as well!
>
> 	73 Ross K9COX
>
> Sent from Mail for Windows 10
>

"legal limit" these days, is simply 1,500w PEP output to the antenna.

*    When an AM transmitter is 100% modulated by a pure sine wave, the 
PEP (Peak Envelope Power), is 4 times the un-modulated carrier power. 
This is because the Audio Voltage modulating the carrier doubles the RF 
voltage at the peak, since the load resistance is constant, the RF 
current doubles at the same instant as the RF voltage. Since P = E * I, 
then P at the instant of the positive peak must be 4 times greater than 
the power of the original carrier


*


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