I've been playing with the RF gain control on the Orion trying to determine
why the background noise does not diminish as the RF gain is reduced. What
I believe is happening is the DSP AGC is compensating for the reduced RF
gain and keeping the audio at a constant volume. The AGC on the Orion is
much better at holding a constant audio level over the receiver's entire
range than anything else I have ever seen. I use programmable AGC and set
the thres hold to 0.37 uv. With this setting, even a .37 uv signal will
have the same volume as an S9+30 signal. If you use fast, medium, or slow
AGC, the thresh hold is 3 uv so the AGC effect will not start until a 3 uv
signal is received.
If you want the typical quieting effect that the RF gain control does on
other receivers, use prog AGC and set the thresh hold very high.
Carl Moreschi N4PY
Franklinton, NC
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