Thank you very much for this tip. I was afraid to put caps on the 
sda/scl lines and now I wish I had. Thank you very much :-)

py2wm wrote:
>
> .. I have had trouble controlling the
> > WB6DHW board probably because of RF feedback and bad grounding on my
> > part.
>
> I've also had this same problem while controlling the Si570 chip from
> the PC parallel port. The symptom was the chip not giving out the
> correct frequency or simply not obeying to the software. The problem
> went away after I added 33pF capacitors at the SCL and SDA inputs
> (header H2) in WB6DHW board. The capacitors leads must be as short as
> possible, SMD types are prefered. The 33pF value is good to the
> intended range (10-200 MHz), a higher value may distort the shape of
> the parallel signals.
>
> It now works smoothly, I specially enjoy SWLing using I2PHD's Winrad
> which does a fine job of controlling the 570 chip with PE1NNZ's DLL.
>
> 73,
>
> JK De Marco, PY2WM
>
>  

-- 
 Regards,
 John
 
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