Dear AL,
On the output side of your 5 VDC power supply put a 100ufd cap at 16VDC, I think the 2.2ufd is much too small for it to have any reserve current if the U3S needs it.??? You may even require more.
beefing up the wire size is a good idea but that also doesn't see to change the symptoms.?? I don't think you need the OCXO module? at all.?? None of mine have it and I have never seen a reason for having it unless your going to use the U3S for a frequency standard.?? One thing that you may also try is to resolder the plug pins and sockets on the SA5351 oscillator module and the main U3S card.? A weak ground connection from the Oscillator to the main board could cause the effect your having.?? Sometimes the plating on the header pins do not solder well as the material they are made from and plated with will give you a good looking solder connection but be resistive to the current flowing through them.? I have had that happen to me but my display was somewhat different than yours.?? I guess it was because it was the IC2 pins on mine and the oscillator just didn't work.?
Good Luck,??
Dave WA5DJJ
