[Orion] AGC/NR Interaction?

[Joe Giacobello]

Gary, thanks for your input.  What you describe may be a part of what I 
am seeing.  Last night I was on 30M and I set the threshold at an 
acceptable noise level and then activated the NR.  It seemed that both 
the noise and the signal increased by the same amount.  In other words, 
there was no change in S/N; everything just got louder.  It was as if 
the NR setting was negating the AGC threshold setting.

However, on another occasion, under what appeared to be similar 
conditions, I obtained the expected quieting from the NR when there was 
either a signal or no signal present.  I am not sure what was different 
about the two conditions.  I kept playing with the NR and threshold 
settings for a while on various signals, but I couldn't identify a 
consistent pattern of behavior.  (I should add that i am running the RF 
gain wide open and that I'm still using the N4PY interface.)  I'll do 
some more experimenting tonight.

I also operated 80M CW during the test.  Unfortunately, I was too lazy 
to compare my FTKMP with the new 4 KHz roofing filter with the Orion and 
just used the Orion exclusively.  Nevertheless, it was my distinct 
impression that I had very few problems with QRM from sigs on 
neighboring frequencies and no signs of overload or IMD or the like.

73, Joe

Gary Tuck wrote:

> Joe, I believe the manual states that you can expect the noise level to
>  increase a bit in some circumstances when the NR circuit is engaged
>  because the Threshold is lowered--the signal to noise level increases
>  though. What I've found is that when I turn on NR, you can no longer
>  effectively adjust the threshold level in the Rx menu. I may have the
>  AGC set to Program adn Threshold at 20uv but when engaging the NR, I
>  can turn the multi knob and the Threshold level numbers change but
>  there is no change in the noise level, even at 191uv. So, it appears
>  to me that the NR circuit makes a Threshold adjustment and then locks
>  out the user from adjusting while NR is engaged.
>
>  I have a strange interaction between the NR circuit and Sweep. If I
>  turn off my rig with the Sweep engaged and then turn the rig back on,
>  the Sweep will freeze every time I turn the NR off. I have to have the
>  NR circuit engaged if I want to use Sweep . If I turn Sweep off and
>  then turn the rig off and then on, the Sweep and NR both work and
>  independently of the others' setting.
>
>  Absolutely a great rig though. I played around in the CW contest in a
>  bit of search and pounce for new ones, and I was continually amazed how
>  close I could hear a station next to a s9+30db signal. If I turned my
> hardware NB off, I often couldn't even tell a pile up was nearby without
>  looking at the Sweep display.
>
>  Gary
>
>
>
>
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