Hi Hans
I tried various setting of the calibration, clutching at straws again, Andy FTDbhas negative values ie. 124,999,xxx mine is 125,000,555 there was no improvement in the narrow 3 Unit WSPR outputted.
I have tried extra decoupling of the DC supply at the DDS pins, no difference.
I have eliminated any possibility of the Output stage feeding back to the generator circuit by removing the LPF and the supply to the output devices. I am now just using the DDS Module output.
Measurements of the output 'Square wave' which is actually sine I think the module is rated for square wave use only to 1MHz from memory.
TX'ing WSPR :-
18.126100MHz - 7.0V pp, 19.126100MHz - 6.5V pp, 20.126100, 21.126100MHz - 6.0V pp, 22.126100MHz - 22.126100MHz
By the time it get to 28MHz it is around 4.0Vpp but I think this is irrelevant, what is happening to the signal generation process is more relevant.
I stopped the measurement here because the fold over point is between 21MHz and 22MHz.
At 21.126200MHz WSPR normal height and 4 Unit WSPR which decodes is generated.
At 22.126100MHz the 'fold over has taken place' the 4th data Unit frequency is absent, I don't think it is an overall compression of the data shift.
Attached and destined for my Files Folder is a Capture which clearly shows a normal transmission at 21MHz followed by a cramped one at 22MHz. The Grab is straight from the screen in real time no cutting pasting etc. has been done so the results are obvious.
Clearly something is happening at this point in the code, arithmetic error or whatever.
Posted to the Group. Please how many Ultimate 2's are there that are OK on 21, 24 or28MHz, there do seem to be some reports from users. Can someone confirm the above 'fold over point'. We need more facts for Hans to investigate the problem.
Andy FTD your requested Set Up Mode........Just press the Left button whilst WSPR is being sent, it goes into Sig Gen Mode like at the end of the 21MHz Trace in the Att..
73 Eddie G3ZJO
