[AMRadio] Only function of carrier

[Stevan A. White]

I'll add this observation to the comments below; some folks have what I 
call "Motorola disease."  They cut off a lot of bass (low freq) response 
which may be OK for an FM repeater but it is the LF response that gives 
the real power to the audio so they're really shooting themselves in the 
foot.  You don't need the bass response growling but don't kill it 
completely either.  I'd pass LF down to at least 100 Hz (lower if you 
like) but keep the upper end up to at least 7.5 kHz; you'll sound a lot 
better, and more natural too.  As a broadcast engineer I am accustomed 
to going up to 125-135% modulation on positive peaks and limiting 
negative peaks to about 95%.  It doesn't add an appreciable amount of 
distortion, it's easy to hear and understand, and it cuts through the 
crud fairly well.  Of course, there's nothing like having everything 
from the mic to the antenna optimized.  It makes a world of difference 
on the receiving end and is easier on your equipment too.

73 de W5SAW, Steve White
> The only function of carrier is to operate the detector circuit.  The time constant is long on the  output of the detector at the IF freq, the carrier converted down to the IF freq. charges this RC circuit up.  As the upper sideband signal, being a higher freq,  adds to the output of the detector as its higher IF freq.  switches the circuit on and off generating more charge, the LSB signal subtracts from this voltage as it's lower freq allows the circuit to discharge.  The output is a waveform that represents the transmitted audio and is sent to the audio amp.  100% modulation on  any RF carrier level is the best you can get for fidelity, but maybe not communication punch through ability.
>
> Now, for the folks that think base response is the be all end all for AM,  weak signals are impossible to copy when you are all base, no highs.  There are a lot of signals I hear with my R390A, Hammer 170A and R4C that could be copyable if only they had full range of audio, but for some reason, their owners bow to the god of low freq range audio.
>
> Charlie, W4MEC in NC