[AMRadio] AM Transmitter "quality"


Jim Tonne tonne at comcast.net
Wed Sep 16 09:25:45 EDT 2009


Regarding 300 to 2800, or 100 to 3400, or  whatever,
I want to bring to the surface another factor.

One of the reasons the usual inexpensive low-end
SSB rigs can sound so obnoxious is that they have
a poor low-end response, as pointed out by several
folks.

Another reason that even moderate-priced SSB
rigs can sound bad is a sharp cutoff rate at either
the low-frequency end (say 300 Hz) and/or the
high-frequency end (say 2800 Hz).

It is the sudden cutoff that the ear dislikes.

I point out the my old 51J4 sound pretty nice if
the mechanical filter is kicked out.  Why?  Not
only because of the increased bandwidth of the 
I.F.  but rather because the shape of the top of 
that filtering system is so rounded.  The cutoff of
the audio frequencies is quite gentle.  Not all
that wide, but the descent into the stopband is
pretty gentle.  

- Jim   W4ENE



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