V3.0.27 Frequency Jitter Observed versus V3.0.19 in CW and SSB Signals

mikeatthebeach .

Looks like it to me !!! See Reference Paper link below The Internal TCXO can get you into issues The Super Stable Low Jitter Source from ERC Works like an Champ solid and no false locks Due to Jitter !!!!! Mike https://www.silabs.com/documents/public/application-notes/AN513.pdf

mikeatthebeach .

Get them surplus off EBay $27 if your lucky to find one https://www.ebay.com/itm/ELECTRONIC-R... Better SNR receiver performance !!!! Better numbers for Sherwood Rating !!! no false locks for just $27 !!!!!!!! Problem solved Flex !!!!!! Mike EE Designer and Consultant WB6DJI

Ted VE3TRQ

That looks really interesting, and the device discussed has the ability to pretty much clean up an incoming clock source :-)

Joe N3HEE

Bill -VA3WTB

Is everyone having Freq stability problems. I have been decoding FT8 for about 6 hours today with the GPSDO turned off in my radio,,no problems here...

Joe N3HEE

Mike's issue was with SSB and CW signals sounding raspy. I've never had an issue with my 6600M and it runs 24/7. I do very little FT8.  If I could improve receiver performance with an external clock for $27 I would surely do it !   Perhaps there are some internal TCXO's that are out of spec.  Maybe a bad batch ?  My radio is well over a year old as I bought a certified pre-loved unit direct from Flex.

mikeatthebeach .

Found a lot of TCXO’s have more Jitter than these Ultra Stable Low Jitter Noise OCXO’s At $27 price Surplus for a 10MHz OCXO I Aligned to a Rubidium Source it a super Steal and a Bargain for an ERC unit Mike

mikeatthebeach .

In all my Observations for This Jitter Problem It all comes down with the Flex6600M Is that there is still an issue After playing with it a lot these days In Trying this below ...... If one Disables the Internal TXCO and enables The GPSDO even though you do not have one, the Radio “searching mode” the radio becomes slightly off Frequency since there is no Loop involved “unlocked state” and the Jitter goes away !! Then switching back to either an internal Or External 10MHz Source to be Locked The Raspy Jitter goes away on CW and SSB Signals Internal Source Jitter shows up sooner within a Day While with an External Source with low Phase Noise And Jitter it takes many days to get the Jitter Issue And Raspy CW and SSB Signals due to Jitter to Appear Sometimes I think it has to do with the Loop Filter BW and Phase Margin of the Loop but perhaps it with the Flex or its software in controlling the locked 10MHz Loop Source that the Issues with theLoop Filter and Phase Margin can be a problem in the loop if Phase Margin is less than 60degrees or a possible synchronization Issue or edge triggering issue from the clock.......You be the one to chose what it might be If the Loop Phase Margin is dependent on The Number of Poles and how close there are Near each other in the of the Loop Instability can occur on the parts that form The Loop when there not enough phase Margin Bode/Nyquist Theory for you techie types Others may think it may be Synchronization Issue on the in the A/D or some adjacent circuitry but who knows unless You actually you were the A/D Designer to know all it’s idiosyncrasies and characteristics It may be hard thing to solve but unlocking the Source and then Locking it up, cycling things back into Sync May be the short term solution if you ever encounter this issue Perhaps a timer to cycle the Locked Source From Locked to unlocked and locked again with. watchdog timer would be a bandaid Fix by the Software Guru’s Perhaps, a Time to ReCal/ReSync for Clock Button perhaps to get around the issues or something with a watchdog timer to activate if Jitter is detected since this is an Elusive Issue not quickly fixed To be fair to FRS -Most Importantly Hopefully it can be resolved at some point in time with further investigation from an Engineering perspective and these problems are not solved immediately to all in honesty Just wish I had more info the A/D and it’s architecture to explore it more since I am always been intrigued by things like this and there causes and ways to find solutions Just my two cents opinion here !! YMMV as they say 73 Mike

mikeatthebeach .

Ted Seems The TCXO In my Flex6600M is a Problem Jitter - Phase Noise - Spurs are a Real https://www.youtube.com/watch?v=G3XK_3Y7bvs Mike Hope Flex can fix it !!!

mikeatthebeach .

https://www.youtube.com/watch?v=G3XK_3Y7bvs

mikeatthebeach .

Good Reading https://ieeexplore.ieee.org/ielx7/58/...https://escies.org/download/webDocume... https://escies.org/download/webDocume...