[time-nuts] Square to sine wave symmetrical conversion (part 2)

Bob Camp kb8tq at n1k.org
Fri Jul 24 20:22:29 EDT 2015


Hi

If your 10 MHz is the result of a “divide by 2 then divide by 5” approach, the output will not be
a 50/50 duty cycle square wave. The best way to fix that is to move up the chain and play 
with the dividers. You need to re-aragne them so the final divider is a divide by 2. 

When you do so, consider that the final divider may be running a hundred ma of supply current
rather than 10 or 20 ma. The shunt capacitor on that filter *does* make a difference.

Bob

> On Jul 24, 2015, at 4:30 PM, skipp Isaham via time-nuts <time-nuts at febo.com> wrote:
> 
> Hello again, 
> 
> First off, I want to thank everyone who replied direct and through the group 
> regarding my recent 10 MHz square to sine wave conversion info request. 
> 
> I obtained a mini-circuits 10.7 MHz low pass filter from Ebay cheap 
> enough and I also plan on "rolling my own" based on some of the information 
> and links provided in your generous replies. 
> 
> Part 2: 
> 
> With things in place, I actually looked at the actual square wave output port with 
> a decent scope to see it's not even close to being symmetrical.  The waveform 
> on-portion (duty cycle) appears (surprising to me) to be much less than 20% 
> 
> Now I'm under the assumption that proper rounding or conversion of the non 
> symmetrical 10 MHz square to a sine wave will be a bit more involved. 
> 
> Before I launch toward part two of this latest saga, I'd really be interested in reading 
> suggestions and comments regarding methods to improve/fix the 10 MHz waveform 
> symmetry. 
> 
> Again, thank you in advance for your replies... 
> 
> Regards, 
> 
> skipp 
> skipp025 at yahoo.com  
> 
> 
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