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Re: [TenTec] Noise and ORION II

To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Subject: Re: [TenTec] Noise and ORION II
From: "pfizenmayer" <pfizenmayer2@q.com>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Tue, 28 Apr 2009 19:21:16 -0700
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
Another factor I have found is that if you are running BW under 300 hz or 
so - the NR becomes less effective on CW (there have been many threads about 
how the DSP NR is working and this follows those discussions) - also my OII 
always requires an increase in RF gain maybe 5 to 7 points or so when the NR 
is switched on .I always run AF gain about 2/3 full and set level with RF 
gain.  I seldom find any condition where anything above NR of 3 helps S+N/N 
. But I have copied MANY very weak signals especially on 80 and 160 with NR 
1 that I simply could not copy otherwise. QSB makes it somewhat less 
effective but still worthwhile to pull out a weak signal.

I do not have extensive use on SSB but at 1.8 to 2.2 khz BW I have been 
impressed at how much it helps readability .For instance the SO4R guys on 75 
SSB were right at the noise and while I could tell they were in there with 
NR off, with NR at 1 or 2 they became copyable well enough to call them. 
(And work them with an inverted Vee at 39 feet from AZ) Is it broadcast 
quality - no - but copy versus no copy is there.

So everyones experience varies as they say  - and there are some noise 
conditions that the NR is not as effective for me. From time to time if 
bands are not too crowded , and on some types of noise , I find that forcing 
the roofing filter to 6 or 12 khz will make the NR MUCH more effective . 
Obviously if bands are crowded with big signals this is not useful. I 
stumbled onto this effect one evening playing with diversity on weak 160 
signals when I noticed that the NR on the SUB rx would wipe out the noise I 
had at the time. Opening up the roofing to match the SUB rx roofing made the 
NR the same on the MAIN rx.

Everything I have said is with AGC Decay at 80 db/sec , Hang  at 0.04 sec 
and threshold at 1 uv .  My measured data on my  O 565 shows threshold is 
little different if at all than reducing RF gain. I have not repeated this 
on the OII but it seems to act the same - For instance watch the S meter 
come up as you reduce RF gain - then  set RF gain full and reduce 
Threshold - - does the same thing.

My two cents worth - Hank K7HP

----- Original Message ----- 
From: "Bob McGraw - K4TAX" <RMcGraw@Blomand.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Tuesday, April 28, 2009 6:08 PM
Subject: Re: [TenTec] Noise and ORION II

> Depending on band conditions and antenna efficiency {not antenna gain}, a 
> RF
> Gain value of 60 may be too high.  With a 1/2 wave resonant antenna on 
> 160M
> and 75M and to some extent,  I run the RF gain in the 30's.  On 10M & 12M
> more RF gain is required due to the fact the antenna captures less signal.
> 73
> Bob, K4TAX

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