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preset pot on AD9850

Wayne Johnson
 

I'm sure it's written here but can anybody tell me what the preset on an AD9850 is for? Tried to tweak it while watching the output level but NG, mind you I only shifted it a few degrees either way


Regards

Wayne VK6EH

Mvs Sarma
 

the sine wave output can be sent to a comparator to convert it to square wave.
 while so, the mark to space ratio can be adjusted by the said pot  as it sends a ref dc to the other input of comparator.
 Hope I could clarify it.

N5IB
 

Look at either one of the square wave outputs on a scope while turning that pot. You'll see the duty cycle change. It has no effect on either sine wave output. On my Type II DDS (little blue pot) I could just barely get to 50%

Jim, N5IB


---In PHSNA@..., <vk6eh@...> wrote :

I'm sure it's written here but can anybody tell me what the preset on an AD9850 is for? Tried to tweak it while watching the output level but NG, mind you I only shifted it a few degrees either way


Regards

Wayne VK6EH

Wayne Johnson
 

Cheers, thanks fellas, I guess we can ignore it for our application, construction is coming along fine with the generator section finished, now working on the power meter (Det.), my PHSNA is self contained with an analogue meter included in the PM.
73
Wayne
VK6EH

Terry VK5TM
 

Just a word of caution.

Certain settings of that pot can add garbage to the sine signal.
Best to remove the resistor coupling the sine output to the comparator if not using it.

Terry VK5TM