[TenTec] DDS PTO replacement for old Ten Tec rigs

Steve Hunt steve at karinya.net
Sun Oct 29 05:53:10 EDT 2017


That function will return a value in variable RIT between -1000 and 
+1000, proportional to the analogue RIT voltage. You then simply add 
that to your required output frequency before executing the function 
that sets the DDS frequency.

So, if the "main" frequency was 5,100,000Hz and the RIT voltage was 
3.75v, that function would return a value for RIT of +534Hz which you 
would then add to 5,100,000 to set the DDS to 5,1000,534Hz.

One thing to check is that the frequency updates are done fast enough 
that the DDS will follow the frequency shifts required during fast keying.

Steve G3TXQ

On 28/10/2017 19:48, Curt Benjamin via TenTec wrote:
> Regarding the Arduino and using one of the analog inputs for RIT, I don't know how to write it into the code in order to experiment but I was told it would be something like this:
> void loop()
> {
>    int RIT = map(analogRead(A0), 0, 1023, -1000, 1000);
> Supposedly, you use the "map" function to take 0-5V on the analog input (A0 in this case) and "map" it to a value from 0 to 1023 and that value can be used to shift the frequency control word going to the DDS module. I haven't the foggiest as to how to write that in, thus the other (possibly cobbled up) way I'm working on doing it.
> Curt, K8AI

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