Date: Wed, 23 Jan 2013 10:46:46 -0330 (NST)
From: jcraig@mun.ca
To: rsgb_lf_group@blacksheep.org
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Subject: Re: xxSPAMxx Re: LF: AD9850 controlled by RS-232
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Hi Graham,

Thanks for the advice.  I've found a 74H00 in the junk heap and
will give the resonant ckt a try soon. It would be nice to use the DDS 
for LO injection so that's why a higher clock freq is desirable. Does 
anyone know if the 74HC00 chip is good to 30 MHz?

Are you are still looking for DDS via serial port control?  You're 
welcomed to my very inelegant basic program though Markus' version is
much nicer.

And the holy grail, which never gives sarcastic windoze backtalk nor
wastes your time booting on powerup, is an ardino board.  It is small, 
easy to program and you can do all sorts of wonderful things with a DDS.

73
Joe VO1NA

On Tue, 22 Jan 2013, Graham wrote:

> Joe,
>
> Looking  at the  app-sheet  , there  is a  clock X 6  function  , that would 
> put the  10 MHz up to  60 MHz  , giving    100 :1  clock / out put ratio ? 
> this  may  be  a  PPL ?
>
> Racal  tended  to  use  xtals , in there  'harmonic'   generators    , 
> feeding  a  low freq   sq wave  , to a   2  stage  xtal filter  , xtals ring 
> in sync  with the   sq excitation , so  phase locked  as  well  .... 10 MHz 
> square wave to  ... what .. say   couple of  high  freq  [cheap] xtals  = 
> stable / clean  HF clock ?
>
> The holy  grail would be  some  sort of 'pic'  device that  loaded  the  DDS 
> on power  on , with a  pre-set   frequency , then   you  have  a real  xtal 
> replacement ..  just needs  to  be  fed  its command  word  by  something ?
>
> 73 -G..
>
> http://www.analog.com/en/rfif-components/direct-digital-synthesis-dds/ad9851/products/product.html
>
> --------------------------------------------------
> From: <jcraig@mun.ca>
> Sent: Tuesday, January 22, 2013 1:35 AM
> To: <rsgb_lf_group@blacksheep.org>
> Subject: Re: xxSPAMxx Re: LF: AD9850 controlled by RS-232
>
>> 
>> 
>> On Mon, 21 Jan 2013, jcraig@mun.ca wrote:
>> 
>>> Hi Markus,
>>> 
>>> but was toying with the idea of doing WSPR via the RS232 and AD09850...
>>> an excellent idea!
>>> 
>> 
>> On the other hand, having just looked at the DF6NM code for the dds and 
>> WSPR and being most impressed by same, perhaps I should focus instead on
>> seeking stability and coherence.
>> 
>> The plan is to multiply a 10 MHz OXCO by three and feed it to an AD9851.
>> Could this be done with the gates of a TTL 7400 to take the sine to
>> a nice rich square then to a 30 MHz tuned circuit to an output gate to the 
>> dds?    Perhaps this is a silly idea.  Either way, comments both
>> negative and favourable will be appreciated.
>> 
>> VX9MRC is still doing CW on 504.1 kHz.  The carrier was generated by a home 
>> brewed ad9850 with tiny connecting wires painstakingly soldered
>> to the pins.  The boards Markus mentioned and Graham recommended a
>> while back are well worth their cost!
>> 
>> 73
>> Joe VO1NA
>> 
>> 
>> 
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>> 
>
>

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