Am a relatively new ham and RFI is not something I am familiar with before the Windom.
Windoms are well known for RFI problems in the shack. There are better all around antennas to use.
DX Engineering stocks snap-on ferrite core kits.
Yep, DXE has some really good ferrite core kits. They work. I had much RFI problems with a Flexradio 5K a couple of years ago. I put ferrites on everything in the shack including my German Shepherds tail. It worked, no more RFI and it cost me $100 worth of ferrites but the GS Dog did not like it much.
I got rid of the Flexradio and put all the ferrites on the shelf. No more RFI problems and my GSD is much happier.