It was type 43 material for the ferrites.
Being a ham I have a lot of different sized ferrite cores, beads etc.
The shielding of the 22 pin 150mm DPI/DSI (display) ribbon did help.
The real issue was the input DC power cable to the display panel.
It was already twisted but not enough for effective common mode reject.
The DPI/DSI ribbon even being shielded was still radiating into/onto the DC power cable.
Twisting the DC power cable further helped.
I installed another LP filter on the DC input to the display board plus two 43 ferrites. This definitely eliminates the DPI/DSI ribbon cable coupling noise.
Still when reassembling the front panel try and keep the DPI/DSI cable away from the display DC power cable. I know they are very close but do your best.
Now able to run the IF level up to high levels(over 70) without internal RFI wiping out the receiver. Running about 55-60 now on IF level verses 15-20 before.
Big improvements in overall S/N.
Also installed ferrite on the main DC input line to the board.
Ferrite on 5v Dc-Dc converter output.
Still have a couple of birdies in LSB on all bands. It’s in the audio passband which makes it sound like a carrier.
I’ll take a closer look at these as it appears to be coming from the Pi4 which I attempted to shield with a cover on the exposed area. More analysis needed.
I hope anyone with a V3 who is experiencing these issues will use this data to make your SBITX perform like it was intended.
Hopefully HFsignals will take a good look at these effective solutions. Possibly incorporate some or all. Cost is minimal.
$20 in parts, 2 hours labor if your old like me. 63 yo…
These modifications are documented. Before and after videos and pictures.
If and when I make progress on attenuating the leftover birdies I’ll inform the group.
Kb4yho