[Orion] AGC/NR Interaction?

[Joe Giacobello]

I have actually delayed the installation of the 1.372 firmware in my 
attempt to isolate the source of the AGC/NR interaction which I have 
described previously.  Unfortunately, there seems to be no identifiable 
pattern.  It is completely erratic and unpredictable.  It arises whether 
I operate through the N4PY interface or not.  The only thing I haven't 
tried is resetting the Orion.

I am going ahead with the new firmware to see if that solves the 
problem.  Thanks to those who supplied their input on this issue.

73, Joe

Joe Giacobello wrote:

> 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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