31 May 2021

Crystal replacement?

Unless you are able to find a low cost source of crystals, they can be very expensive these days. Some people have turned to Si5351 synthesiser boards as an alternative. I believe they can be programmed to provide outputs from kHz to VHF frequencies. But can these work with the programming source  removed so this is a true crystal replacement? Please let me know if you know how. 

If they can be used "stand alone" they become far more useful if they can be easily programmed. The ideal would be easy programming with a PC or Mac or even Android and then essentially a free standing oscillator module.

2 comments:

Peter Marks said...

As far as I know, no, you need something to load up the programming on the Si5351 on power up. There are tiny microprocessors that could do this task for a few dollars though.

W5OLF said...

Roger, my understanding of this is now that the SI5153 can not be used in a standalone manner. One might be able to use dedicated, very small, microcontrollers for this (such as ATTINY) but to my knowledge there does not seem to be a crystal that is truly programmable. Also in looking at tdhe SI5351 output on SDR/Argo there is wandering sidebands close to the carrier. These may make useful oscillators for some digital modes but WSPR, for example, makes it somewhat undesirable. That said I have seen on eBay Chinese TCXO dip-14 packages that can be ordered at any frequency for about $20. I am going to evaluate one of these soon and see if they have any tail-tell sidebands. I like you very much wish the SI5351 was programmable in a standalone manner. Jay, W5OLF