Bill,
Thanks again for great input.
Distortion.
Roofing filter 6kHz or 2.4kHz SSB mode.
20m. Lsn to week signal at 14.220 with preamp ON.
Distortion, so I tune up 7kHz and there we go S9+37dB station.
Turn off preamp and dist. gone.
No problem, but long term DSP should handle this.
2.0 please. Hi Hi.
73! Mark WQ7X
>
> From: Bill Tippett <btippett@alum.mit.edu>
> Date: 2005/05/24 Tue PM 12:37:16 EDT
> To: tentec@contesting.com
> Subject: [TenTec] My new ORION
>
> I wrote:
> >Mark, I suspect this is related to the same DSP
> overload issue.
>
> While making my daily bike ride to the Post
> office, I was thinking more about this issue. In
> both the CQ 160 CW Contest in January and in the
> ARRL DX CW Contest (SOSB/160) in February, I do NOT
> recall having any distortion problems. I was then
> using 1.373b4 since I'm a beta tester and I found
> this comment in the version history:
>
> > Version 1.373b4
> > - Eliminated passing of AGC info to DSP. This was causing Out Of Band
> > distortion when used.
>
> Nevertheless, I HAVE noticed in-band distortion at
> times since then and believe there could be at least
> 3 different issues involved in your situation:
>
> A. Which roofing filter were you using when you
> noticed the problem? If you are using anything in
> Orion's 500 Hz slot, that is a known problem for
> degrading IMD and you can solve it by simply
> disabling that position. If you want a narrow
> filter with even better IMD than the stock 1 kHz,
> Inrad's #762 improves Orion's already exceptional
> IMD performance by 6-10 dB at 2-1 KHz spacings.
>
> http://users.vnet.net/btippett/inrad_.htm
>
> B. Is the distortion on in-band signals
> or are you hearing out-of-band generated IMD
> products (sounds like code other than Morse)?
>
> If the former, this is the same problem I've heard
> but there may be a simple work-around. Until I
> learned how to use the "new" RFGAIN control, I
> always set AGC Threshold fairly high (e.g. 20 uV
> on 160m and never below 3uV on 10m). After I
> learned how to use the new control, I simply
> set 3uV for everything and then used only RFGAIN.
> It may be that I began noticing the distortion
> problems after doing this. The problem you can
> run into is that you can "waste" the DSP's dynamic
> range by setting Threshold too low, and there is
> no limit on the upper end due to the FW bug. A
> simple work-around may be to set AGC Threshold
> to 3uV or higher (no need for it to ever be lower
> than 3uV on ANY band), then listen on the band
> of interest with RFGAIN fully CW. Turn RFGAIN
> back fully CCW (0%), and advance it until the band
> noise sounds the same as full CW. This should be
> well below 100%, and now the DSP will have more "top
> end" before distortion occurs. I agree it should
> be impossible to overdrive the DSP but this might
> be a work-around until Ten-Tec fixes that bug, and
> it also seems to explain why I never had problems
> in 160 contests in some of the worst QRM known to
> mankind.
>
> If the latter in B above, and you do not have
> a bad roofing filter, then there may be something
> else wrong with your unit. But it is definitely
> a specific problem and not generic to all units
> or Orion would not perform so consistently well
> in 4 independent tests. It could be the "Out
> of Band" distortion problem in 1.372 mentioned
> in the 1.373b4 release is causing this problem.
> Unfortunately Ten-Tec has not yet released this
> so I cannot send a copy to you to try, and they
> are now totally focused on the 2.0 rewrite and
> we don't want to distract them from that.
>
> Another suggestion is to simply call Paul
> Clinton at Ten-Tec. If you haven't experienced
> Ten-Tec service before, you're in for a pleasant
> surprise!
>
> 73, Bill W4ZV
>
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