On 1/19/2011 8:21 AM, Jim Sheldon wrote: > I've had several queries on this so I'm posting here - I have no idea what ferrite material is It makes no sense to buy unknown ferrite cores, especially for use on the HF bands. Study my tutorial on RFI to understand why. http://audiosystemsgroup.com/RFI-Ham.pdf 73, Jim Brown K9YC