On Sun, 2006-06-18 at 19:30 -0700, Duane - N9DG wrote:
> --- "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
> wrote:
>
> > It should be present in the Orion too,
> > unless the 5 MHz circuit is really well shielded.
>
> ???? What 5 MHz circuit in the Orion????
>
> My understanding of the Orion schematic is that the UHF
> "synthesizer" is divided down to ~10-~39 MHz for the 1st LO,
> there isn't any 5-5.5 MHz circuit anywhere. The Omni VI's yes
> but not the Orion...
>
With 9 MHz IF, it takes 5 MHz to mix to get to 14 MHz. Always has been
that way ever since the first phasing rig using a 5.3 - 7 command set
was used for the VFO with a 9 MHz IF. I suppose with adequate side band
switching the Orion could use 23 MHz LO for 14 and 30 MHz for 21 MHz to
keep the PTO birdie from showing, but that means the UHF synthesizer has
to make smaller steps to keep them reasonable at HF, though the DSP
should be doing some of that fine tuning.
--
73, Jerry, K0CQ,
All content copyright Dr. Gerald N. Johnson, electrical engineer
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