[hpsdr] Proposal for a 'low-end' RX/TX board for HPSDR

[CT1IZU]

----- Original Message -----
From: "Richard Hosking" <richardh at iinet.net.au>
Cc: <hpsdr at hpsdr.org>
Sent: Sunday, July 23, 2006 2:03 PM
Subject: Re: [hpsdr] Proposal for a 'low-end' RX/TX board for HPSDR


***** High Performance Software Defined Radio Discussion List *****

<I have been contemplating this further
<The unit would cover HF
<I would see the board as containing
>LO (DDS? - I have a footprint for the AD9951 worked out tho I havent
>built the board)
>divider (divde by 4 to give quadrature?)
>Tayloe style mixer
>opamps
>front end filters (multiple LPFs - switched)

>Would be interested in comments on each of these sections - the best way
>of implementing

Divide by 4 pushes the dac to less favorable frequencies. 2xAD9951 might
work better using the phase offset reg. I tried a KK7B rx using this system
with 2x AD9851. On 40mters at night with all the euro bc qrm it was
impressive, I think the production group only went over to PLL because of
the spur problem with 10bits and the 180MHz clock.

Putting filters on the board gets us back to limiting its use to a given
band or bands. Lyle has use for a duo-bander, I `d like 10 and Fred down the
road only wants a Soft ROCK. As I said in an earlier post makes more sense
to make the board 0-30MHz and do the filter on another board either single
or multipole tx/rx etc.

Shel CT1IZU



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