On 4/12/2024 1:37 PM, Dana Myers via wsjt-devel wrote:
In addition to Joe's admonishment here, I note that the Si5351 spurs due to jitter can easily be strong enough (~ -45dBc) to interfere with adjacent FT8 signals. I'm not sure it's a good idea to use an Si5351 to generate a transmit signal of significant power (> 10dBm perhaps) without special care.
After a closer look, I've found the relatively large spurs aren't as common as I'd first thought. For example, using a 25.0MHz xtal reference with a -221Hz offset, thus a 24.999790MHz xtal, I see large spurs ~220Hz either side of 25.0MHz out. However, between 26.0 and 26.025MHz, spurs are greater than -60dBc. It is a wake-up call for me to take greater care when using Si5351 in a transmit chain, though. 73, Dana K6JQ _______________________________________________ wsjt-devel mailing list wsjt-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/wsjt-devel
