Re: #synth ref frequency #synth

Hans Summers

Hi Halden

SiLabs engineers confirmed somewhere on their forum that although the datasheet says the reference crystal should be 25 MHz OR 27 MHz, in fact anywhere in the range 25-27 MHz os what they really meant. So according to that you can use 26MHz without disadvantage. 

Use of 10MHz works but is way outside spec; aside from reducing the upper frequency limit you can attain, it also degrades the spectral purity. It doesn't matter on low frequencies but on VHF it seemed quite bad - there was a post in this forum ages ago about it but I can't find it now. 

73 Hans G0UPL 

On Thu, Mar 25, 2021, 05:36 HF via <> wrote:
Hi all...
The Si5351a datasheet says its reference frequency has to be 25 or 27 MHz.  Others here have commented on using 26 and 10 MHz.  What are the disadvantages of using other frequencies, other than the inconvenience of scaling the divider settings to compensate for use of a non-standard reference?
Halden VE7UTS

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