Hi Ford,
If the "splatter" in question is generated in the offending
stations transmitter, then the only thing you can do is turn
your antenna away from him since the interference actually
falls onto your operating frequency.
If the offending station transmit signal is clean, then the
interference is probably being generated in your receiver.
A quick way to check this is to put some attenuation in front
your the receiver. If the distortion drops more quickly than
the signal levels, then distortion is being generated inside
the receiver. This is because the kind of interference that
is generated inside of receivers (intermodulation distortion)
is very amplitude dependent and falls off rapidly when input
signal levels are reduced (the so-called third order
intermodulation distortion products fall off 3dB for every
1dB drop in signal level).
In terms of your question about sideband suppression, this
is seldom a problem with modern transceivers. The main problem
is intermodulation distortion which has nothing to do with
sideband suppression. The reason for this is simple, unwanted
sideband suppression in an HF transmitter is done at an
intermediate frequency at a fairly low power level where
amplitude distortion (intermodulation distortion) doesn't really
come into play too much. The sideband suppression is set by
the selectivity of the crystal transmit IF filters which
have very sharp selectivity (some of the newer rigs may use
DSP techniques to do this).
Once the unwanted sideband is removed, the transmit signal needs
to amplified from a low level (on the order of milliwatts) up
to a high level - 100 to 150 watts. Since the amplifiers used in
this process only have finite linearity, the various components
of the voice signal will invariably cross modulate each other to
some degree producing intermodulation distortion products, i.e.
splatter. This splatter is very drive dependent, so in the same
way that the intermodulation distortion products generated in a
receiver drop off quickly as the signal level is reduced, the
intermodulation products generated by a transmitter increase
rapidly as the drive power level increased. Automatic level
control (ALC) is supposed to mitigate this to some extent, but
some have commented recently that ALC circuits used in some of
the modern transceivers are of inferior design.
Hope this answers, your question!
Mike, W4EF.................
P.S. Does this mean I can now ask you questions about my taxes -
grin grin........
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