[TenTec] DDS PTO replacement for old Ten Tec rigs

[Mike Bryce]

Oh crap!

I just had an ah hah moment.

With the SB-104, I need to offset the VFO slightly when going from CW to LSB. I think CW and USB have the same offset.
That radio does not use RIT.

I guess it would be possible to use a small trimmer and dial in the necessary offset in the form of a voltage and apply that to RIT function.

A simple transistor switch will put the offset circuit in and out as needed.

Only problem is, I don’t have a  clue on how to modify the sketch to do that.

mike, wb8vge

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> On Oct 29, 2017, at 5:53 AM, Steve Hunt <steve at karinya.net> wrote:
> 
> Curt,
> 
> 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
> 
>