Hans Summers has experimented with pushing the Si5351 PLL chip beyond its 225mhz max spec,
he got up to around 290mhz before it crapped out.
/g/BITX20/message/52046Apparently some chips (at some temperatures and at some supply voltages) can do 300mhz, but not all.
Hugen's solution of reducing the max frequency out of the si5351 from 900/3=300mhz
down to 800/3=266.66mhz is apparently enough to make it work across all devices.
Given that there was a spike at 600mhz (in addition to 300mhz and 900mhz),
it is apparently using the 2'ed harmonic, in addition to the fundamental and 3'rd harmonic.
Perhaps the firmware could allow the user to attempt going all the way to 900mhz
on the third harmonic, with the understanding that it may fail up near the very top.
But continue to have gear-shifts at 266.66mhz and 533.33mhz as per the 800mhz firmware.
Jerry, KE7ER
On Thu, Jul 4, 2019 at 05:55 PM, <hugen@...> wrote:
Peaks occur because si5351 is working at the limit£¬I will update an 800MHz
firmware later to improve this problem.
Thank you£¡
hugen
gen111.taobao.com
