[Elecraft] RF feedback problems with P3 and external keyboard

[G4GNX]

I haven't connected a keyboard to my P3 yet, but I have had issues with the 
shack PC.

It's been fine on 160m thru 20m but I had issues above 20m when I changed 
keyboards. As the original keyboard that I used was OK re-connected it and 
forgot about it.

Last Wednesday with the original keyboard connected, I was on 20 metres when 
the lights on the keyboard went off and there was no output to the PC. I 
found the cure was to use a large Type 31 ferrite ring and wind 4 turns of 
the keyboard USB cord onto it, right close to the USB connector at the PC 
end.

Perhaps this will help you with your P3 issue.

73,

Alan. G4GNX

-----Original Message----- 
From: ANDY NEHAN
Sent: Friday, November 24, 2017 8:34 PM
To: elecraft at mailman.qth.net
Subject: [Elecraft] RF feedback problems with P3 and external keyboard

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