[hpsdr] CVCSO-914-1000

[Philip Covington]

I did not post this specifically with Phoenix in mind.

It was mainly the fact that this might be an option for those looking
for a 1 GHz clock for use with the AD9912 with the advantage that it
is an off the shelf part.

Phil N8VB


On Mon, Feb 25, 2008 at 6:50 AM, Grant Hodgson
<grant at ghengineering.co.uk> wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
>  The CVSO-914-1000 is certainly a good part, but being SAW based means
>  that the close-in phase noise is not as good as a well-designed crystal
>  oscillator such as the ones that Chris GW4DGU has recently reported.
>
>  My quick calculations suggest that using the CVSO would worsen the phase
>  noise by about 8-9dB or so, compared to using a crystal oscillator at
>  116MHz and then using the 9912s on-chip PLL clock multiplier.  If an
>  external x8 multiplier were used, the resultant phase noise would be
>  slightly better, but for now I believe that the working assumption for
>  Phoenix is to use a VHF crystal oscillator with the 9912 PLL.  This is
>  felt to be a good compromise between performance/cost/complexitiy/design
>  effort etc., and should result in an LO that will outperform the Orion
>  on all bands at all carrier offsets, with the exception of 28MHz at
>  offsets closer than about 1kHz or so - and even then Phoenix should be
>  better than the SDR-1000 and hopefully better than the Flex 5K.
>
>  My personal belief is that it is the close-in phase noise that
>  determines the 'quality' of an LO; it can be a particularly difficult
>  parameter to optimise, and can also be quite difficult to measure.  But
>  the effects are real - poor close-in phase noise on either transmit or
>  receive can cause interference with only a single, strong signal on the
>  band.  So it's worth spending some time and effort aiming for a very
>  clean LO; Phoenix should in theory be able to do this.
>
>  regards
>
>  Grant   G8UBN
>
>
>  > Subject:
>  > [hpsdr] CVCSO-914-1000
>  > From:
>  > "Philip Covington" <p.covington at gmail.com>
>  > Date:
>  > Sun, 24 Feb 2008 15:46:50 -0500
>  > To:
>  > "HPSDR Reflector" <hpsdr at hpsdr.org>
>  >
>  > To:
>  > "HPSDR Reflector" <hpsdr at hpsdr.org>
>  >
>  >
>  > Maybe a candidate for use with the AD9912 DDS?
>  >
>  > <http://www.crystekcrystals.com/crystal/spec-sheets/vcxo/CVCSO-914-1000.pdf>
>  >
>  > It is not cheap (~$116 ea) but is in stock at Mouser for one...
>  >
>  > 73 Phil N8VB
>  >
>  >
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