[AMRadio] FCC's AM power


CL in NC mjcal77 at yahoo.com
Thu Sep 22 22:41:49 EDT 2016


I was pondering the old rule of thumb for power in the sidebands of a 100% modulated AM transmitter and got to wondering about our power restriction on AM.  A CW station or SSB station can put 1500 watts into one information carrying signal.  

So, why is it we are restricted to only 375 watts of plate modulated AM which supposedly is equal to 1500 PEP watts of CW and SSB, when this really only equals 93.75 watts per sideband for a total of 187.5 watts of actual information signal.  If we could put the equivalent 1500 watts into our information carrying part of our signal, that would be 750 watts per information carrying sideband, 1500 watts of actual info signal, being generated by an unmodulated power out of 3000 watts. This would be a total Power(total)* of 4500 watts, but, even if we rolled it back to a total power of 1500, that's a 1000 watt carrier with  500 total sideband information signals, still only 33% of the CW/SSB 1500.  So, to be absolutely fair,  with this difference in sideband information carrying powers, it would seem a power reduction is in order for CW and SSB operators such that their actual information carrying signal is not greater than the total power in the sidebands of an equivalent legal power out DSB AM signal, 187.5 watts PEP. 

Of course that will never happen, but there is a great inequality in this restriction that maybe the ACLU could take on as discrimination against the bi-sideband lifestyle.

Never ponder after two PBR's

Charlie, W4MEC in NC

*  Power(total) = Carrier power X (1 + m(sqrd) / 2)  where m = decimal equiv. of mod percent


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