[EMAIL PROTECTED] wrote:
Well, sorta kinda. If the unwanted signal gets in and pumps the AGC, then
the DSP might knock down the signal but won't be able to do anything about the
AGC pumping. Then, you won't hear the signal if it is weak. That is the
whole issue of the DSP being in or out of the AGC loop and it generated a
mountain of controversy with the Orion when TT moved the DSP to within the loop.
The K3 has two AGC loops. One is part of the DSP, so as long as the DSP
does not overload, a signal outside the DSP passband but within the
crystal filter passband will not cause the AGC to pump.
But, if the signal is greater than, I think, S9+30 (30 dB above 50 uv),
then it might overload the DSP. So in that case, the analog AGC which is
outside of the DSP kicks in to prevent that, and you would notice a gain
reduction on the desired signal.
This is where you could use a narrower roofing filter. I ordered 2.8,
1.0, and 0.4 KHz filters. I noticed this effect with huge signals by
listening with the bandwidth set to 450 Hz, which uses the 1 KHz crystal
filter. Moving it to 400 Hz causes the narrower filter to be activated,
which eliminates the pumping.
--
73,
Vic, K2VCO
Fresno CA
K3 no. 00007 ('James')
http://www.qsl.net/k2vco
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