|[AMRadio] New Year's Resolution-Getting Back on AM!|
k4kyv at charter.net
Wed Dec 27 12:31:59 EST 2006
> There are others that say that monitoring your envelope pattern isn't
> good enough, if you have a scope... you should be watching the
> Trapezoid pattern, instead.
One problem with monitoring the trapezoid pattern all the time is that it
will burn a dark vertical line onto the face of the scope tube, where the
unmodulated carrier appears. The trapezoid pattern is useful for indicating
the linearity of the modulated stage, but the envelope pattern gives a
better idea of the actual quality of the signal, since flat-topping and
waveform distortion are easily apparent.
The evelope pattern will burn a horizontal line where the bright no-signal
baseline appears, if you don't disable the scope when not transmitting.
This can also be a problem with CW and SSB operation, since the bright
baseline is there during pauses in modulation or keying, just as the
vertical line is there during pauses in AM modulation when using the
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