[Orion] Orion Receiver Audio Background Noise

[N0KHQ@aol.com]

Message: 3
Date: Wed, 2 Mar 2005 08:38:35 -0500
From: "Robert  Carroll" <rlcarroll at patmedia.net>
Subject: [Orion] Orion Receiver Audio  Background Noise
To: <orion at contesting.com>
Message-ID:  <20050301133959.33DA93888E at mxo2.broadbandsupport.net>
Content-Type:  text/plain;    charset="us-ascii"

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 
 
Hi Bob, 
 
I know exactly what your talking about. I did the same thing you did, ran  
the Orion into a dummy load. The receiver was so noisy I couldn't stand  it.
 
But, that was before I figured out how to operate the rig! DUH!
 
Set up your Programmable AGC on both receivers as follows:
 
Hang = 00.30 s
Decay = 5 db/s
Threshold = 00.37 uv
 
You will probably never have to get into the AGC settings ever again.
 
Now, the determining factor as to how much noise (sensitivity) you  want to 
hear will be determined by the setting of the RF Gain control for each  
receiver.
 
Like right now, I'm on 40m. The Main receiver RF Gain is set to 58, the Sub  
Receiver is set to 52. I also have 12db of Attenuation on the Sub Receiver  
because it has a pre-amp that cant be turned off.
 
You will find that the RF Gain settings for the Sub Receiver will be 6 to  8 
% less than the Main RF Gain Receiver settings.
 
I adjust the RF Gain settings on my Orion down to a point that the band  
noise goes away.
 
AAAHHHH! How sweet it is.
 
I like the receiver on the Orion so much that I got rid of my TS-850SAT,  
TS-950SDX and IC-756 Proll. I've got one rig left that I've just got to keep,  
the TS-830S, I love that old rig.
 
Have fun Bob. If you run into anything else that's not clear to you send me  
an email with you phone number and I'll call you.



73

John / N0KHQ / St.  Louis