[AMRadio] AM Transmitter "quality"


Joe Hankins joe_hankins at lexcominc.net
Tue Sep 15 14:11:05 EDT 2009


I really don't care whether people chose to modify their old AM 
transmitters to "improve" sound quality, as they can do whatever they 
want with their radio. What does bother me a little is when people use 
words like "nasty" and "awful" to describe the audio quality of some 
classic transmitters, as if thedesigners of the day were not smart 
enough to design a decent transmitter.

At the time these transmitters were built, the goal of amateur pone 
operation was effective radiotelephone service. Human speech falls into 
the range between 300 and 3000 Hz. There are sounds outside this range, 
but they do not contribute to intelligibility. So, in order to make the 
best use of the power available,  the bandwidth didn't need to be more 
than 4Khz.  The next logical step in the quest for efficient use of 
available power was SSB, which has an equally "nasty" sound but does the 
intended job quite well.

By modifying a transmitter to increase the audio bandwidth, all that is 
being done is to get it closer to the commercial broadcast transmitters 
of the day, which needed much greater bandwidth to handle music.

Joe
KN4JH


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