[time-nuts] 10MHz Square to Sine Wave Conversion

Magnus Danielson magnus at rubidium.dyndns.org
Fri Jul 17 04:07:55 EDT 2015


I was thinking along these lines.
Cooking up a 3-pole filter in the form of a Pi-filter should be a good 
start, and then add traps for third and possibly fifth overtones that 
will not get much damping initially can be done if you need it pretty clean.

Cheers,
Magnus

On 07/17/2015 04:07 AM, Graham / KE9H wrote:
> All you need is a 10 MHz low pass filter.
>
> How far down do you need the harmonics/spurious to be?
>
> If 40 dB suppression of the 2nd and 3rd harmonics is adequate,
> (you can't see the distortion with the eye on an oscilloscope)
> you can make your own for about $2 in parts, not including a PC board or
> housing.
>
> Feel free to copy the low pass filter (L1, C9, C10) from here:
> http://openhpsdr.org/wiki/index.php?title=EXCALIBUR
>
> Or for about $35, you could get the same performance from an inline BNC
> filter from Minicircuits.
>
> http://www.minicircuits.com/pdfs/BLP-10.7+.pdf
>
> If you need more harmonic suppression, buy two and put them in series.
>
> --- Graham
>
> ==
>
>
>
> --- Graham
>
> ==
>
>
>
> On Thu, Jul 16, 2015 at 12:49 PM, skipp Isaham via time-nuts <
> time-nuts at febo.com> wrote:
>
>> re: 10MHz Square to Sine Wave Conversion
>>
>> The GPSDO I recently acquired outputs a 10 MHz square wave. I'd like
>> to convert it to a sine wave and I am looking for suggestions and info re
>> any reasonable pre-made circuits and/or boards. No sense reinventing the
>> wheel if I can avoid it.
>>
>> Otherwise I will start from scratch and make a new wheel....
>>
>> Thank you in advance for your replies.
>>
>> Regards,
>>
>> skipp
>>
>> skipp025 at yahoo dot com
>>
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