[TenTec] Orion Synthesizer Design

[Steve Baron - KB3MM]

Much different from the OMNI V?
----- Original Message ----- 
From: "Bill Tippett" <btippett at alum.mit.edu>
To: <tentec at contesting.com>
Sent: Wednesday, April 13, 2005 18:30
Subject: [TenTec] Orion Synthesizer Design


> W3ULS:
>  >Can someone explain the seemingly large discrepancies between the 1993
> QST transmit composite noise and the 2003 Ten-Tec phase noise graphs for
> the OMNI VI?
> 
>          It could simply be poor resolution of the photo
> of the 1993 spectrum analyzer plot.  Compare the following:
> 
> January 1993 QST Review of Omni VI, photograph on page 5...
> http://www2.arrl.org/members-only/prodrev/pdf/pr9301.pdf
> 
> ...to plot on p. 18 of the Omni VI+ Expanded Test Report from
> 1997.  It looks much better even though I expect the synthesizer
> designs (VI versus VI+) are basically identical.
> 
> http://www2.arrl.org/members-only/prodrev/pdf/lab/omni-6.pdf
> 
>          Orion's phase noise below 2 kHz is a major contribution.
> Assuming 130 dBc/Hz, and adjusting 27 dB for noise bandwidth,
> this means Orion's phase noise is -103 dB at 2 kHz using a 500
> Hz bandwidth filter.  By comparison, both the Elecraft K2
> and Icom IC-7800 had IMD that was "phase noise limited" at
> 2 KHz spacings using 500 Hz bandwidths.  Sherwood's IMD
> measurements of 80 dB at this spacing implies the phase noise
> of both rigs were about 23 dB worse than Orion at 2 kHz.
> 
> http://www.sherweng.com/table.html (see footnote "f")
> 
>          This also indicates why adding narrow roofing filters
> alone (e.g. new Inrad for Omni VI or Yaesu MP) can only go
> so far without running into phase noise limits of the basic
> synthesizers.  Even more amazing is that Orion holds <130
> dBc/Hz down to 200 Hz spacings!  This means that a very
> narrow filter like the 600 Hz Inrad #762 can be used to
> full advantage at extremely narrow spacings without any
> degradation due to phase noise limiting.
> 
>          In looking at the article, I see it was written July 21,
> 2004.  I wonder if Ten-Tec used the time before publicly
> releasing it to apply for patents?  I sure hope so!  This
> is a REAL contribution to the state-of-the-art, unlike the
> unabashed marketing HYPE coming from other manufacturers.
> 
>                                                  73,  Bill  W4ZV  
> 
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