The Orion receiver is the best I have used, but there is an aspect of it I
don't understand and don't particularly like. I think back to some of the
early transistor portable radios-about 1959 or so. The sound from these
sets was pretty good, but when you turned the volume control fully down so
that you couldn't hear a station there was still a audible shhhhhhhhhhh
noise from the speaker. With my Orion if I connect a dummy load to the
antenna input I still get a "shhhhhhhhh" which is clearly audible on the
speaker or headphones. Any real signal input is enough to overcome this
background noise, but to me it is annoying. When I crank down the audio
gain on my MP and Pro, all audio background noise disappears. With the Orion
I find that when the AF gain gets very close to zero on the bargraph there
is a click and the shhhhhh is gone, but at the 2-3% point it is back and
increases with the AF gain control. Activating NR removes most of it.
Cranking back the RF gain control lowers it, so I assume it is generated by
DSP activity of some sort. To me over a period of time on cw using
headphones this background noise is fatiguing. I wonder if this is the root
of some of the "noisy receiver" complaints that appear from time to time.
Has anyone else noticed this? Is it a necessary "feature" of the digital
processing being used?
Bob W2WG
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