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Re: [TenTec] [Fwd: Is the Orion Noisy?]

To: tentec@contesting.com
Subject: Re: [TenTec] [Fwd: Is the Orion Noisy?]
From: Curt Gamble <W0ALC@Mindspring.Com>(by way of Bill Tippett<btippett@alum.mit.edu>)
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Tue, 19 Dec 2006 13:10:52 -0500
List-post: <mailto:tentec@contesting.com>
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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