[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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