[Lowfer] AD8932 DDS info...

[Johan Bodin]

Hi Scott,

[...]
> and I'm finding that it does "once" and while put the correct =
frequency
> out; however, as I change VFOs or hit a key on the keyboard "unstable"
> behaviour occurs.  I've tried various computers and wiring layouts and
> the behaviour is the same... Is the speed setting critical?

The speed setting (if you mean "port pin slowdown"?) is not very =
critical.
Check the signals with an oscilloscope, if available. They should look
reasonably "square". If the clock and/or data pulses are very short and
"needle like", increase the "port pin slowdown" value. You may have a
problem with slow rise/fall times. One trick is to put schmitt triggers
(74HC14) at the DDS end of the cable (don't forget to set the "bit
inversion mask" since the 74HC14 is inverting).

What is your operating system? Vfo.exe is a DOS program and may
not behave well when run in window$. Do you have a long cable
between the printer port and the DDS?

73
Johan SM6LKM