[Elecraft] RF feedback problems with P3 and external keyboard

[ANDY NEHAN]

After LOTS of experimentation I think I have found that just recently I have some RF feedback into the usb keyboard on the rear of the P3. This manifests itself particularly badly with the Genovation keyboard but is also present with a standard usb keyboard. Oddly enough it is MUCH worse when using the Perwerx psu than my linear psu - but that may of course be due to different cable layout for the power cables. I have applied clip on ferrites with great enthusiasm but to no avail. 
I noticed a message on my external vga screen saying "usb device removed" shortly after starting to transmit and then shortly after that (but whilst still transmitting) "usb device connected". This is also not present when on low power (say 5 watts) but reappears at 20 watts.
Has anyone else experienced this problem??
Andy