See comments from Rob NC0B via Curt W0ALC below:
Ron N6IE wrote:
Bill: Have you mentioned this to Dits 'n Bits? I noticed the same problem
with the 2.037j update, but increasing the hang time seemed to fix the
problem.
I think I did but may do so again to be sure.
It's hard for me to describe it other than saying 2.059
makes impulse (lightning) QRN sound "scratchy". I never
noticed the problem Rob was complaining about, and
apparently he agrees the "fix" in the latest V2 versions
(which I think apply to both rigs) are not right.
73, Bill W4ZV
P.S. to NQ5T. Rob bought an IC-7800 but I believe has
since sold it and is back to his IC-781.
Rob & Terri Sherwood wrote:
My comments to Bill, W4ZV.
The noise issue has to do with DSP and AGC. The front end redesign
had to do with optimizing the close-in dynamic range.
These are two completely different subjects that have nothing to do
with each other.
Yes Bill is correct that the ARRL first reported the dynamic range
issue with the Orion I and the 500 and 250 Hz roofing filter
positions, but no one seemed to take note of the problem until after
my talk at Dayton. At that time, Jack Burchfield and I started
working on a solution, and that resulted in the elimination of the
two amplifier stages, 4-pole filters for less loss, and putting all
7 filters in one bank in the Orion II. The 95 dB close-in dynamic
range of the Orion II is now limited by the linearity of
the roofing filters themselves, and at this high level is more than
adequate for any ham.
I was not aware that the Orion I AGC code had been changed. There
are many AGC issues on the Orions. One is how the AGC functions on
very weak signals that are just beginning to run the AGC, and the
other is how the radio responds to transient noises, like clicks,
ticks, pops and QRN. All recent DSP radios are exaggerating
transient noises. Ten-Tec put part of the AGC code from the RX-340
into the Orion II, and maybe the Orion I. I did not like the "fix"
either, as the AGC still is over reacting to transients, instead of
ignoring them like the Omni, or a Pro III or a 781 or a Drake
R4C. Issues of noise and AGC is a big problem in my opinion that
still needs a lot of work by all the manufacturers.
73, Rob, NC0B
-------- Original Message --------
Subject: [TenTec] Is the Orion Noisy?
Date: Tue, 19 Dec 2006 07:31:53 -0500
From: Bill Tippett <mailto:btippett@alum.mit.edu><btippett@alum.mit.edu>
Reply-To: Discussion of Ten-Tec Equipment
<mailto:tentec@contesting.com><tentec@contesting.com>
To: <mailto:tentec@contesting.com>tentec@contesting.com
W0EWM:
> If you read the full text of
> Rob's post (Yahoo ICOM-7800 Group MSG# 4755) you will also
> find Rob's comment "After working with T-T, they redesigned
> the front end to my spec, and eliminated the two amps, and
> put all 7 roofing filters in one bank." I'm guessing Rob has
> a reasonable working knowledge of the performance issues of
> the Orion and Orion II.
NQ5T:
>That may well be. And I wouldn't posit otherwise. So even after it was
redesigned to his spec, it's still "noisy".
With all due respect to Rob, it was ARRL that
first discovered the IMD problem with the 500 Hz filter.
It was my initiation of the Inrad #352 600 Hz filter kit
in January 2004 that solved the problem. Inrad later
offered this as a complete unit (their #762 filter) and
implemented the single bank idea in Orion II. Rob
didn't get an Orion to measure until late April 2004
when he was writing his Dayton paper.
Unfortunately Rob made one suggestion to Ten-Tec
regarding AGC attack times which has made the latest V2
unusable in my opinion. I could live with its other bugs
but the AGC Attack "fix" has made the most recent V2
sound extremely scratchy (noisy?) to my ears. I'm hoping
Ten-Tec will reverse that "fix" one of these days.
73, Bill W4ZV
P.S. My comments on V2 are for Orion not Orion II, but
supposedly they share much of the same basic code.
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