Ken, When you do the research and math, worth bearing in mind that powdered iron (and ferrite) cores can generate intermodulation products. Usually this problem will affect the "receive" performance of an antenna matching network, or a receiver's front end filters, if exposed to strong signals e.g. SW Broadcast.
The root cause of this IMD problem can be traced back to the magnetic flux generated in a core by the incoming signals. The flux density is proportional to the applied voltage (vector sum of incoming signals), and inversely proportional to the core's cross section (area), the number of turns and the frequency. Thus the number of active turns should be as large as possible, the loaded Q of the network should be kept low, the core's mu low in value, and a large core used. Sorry to be late with this comment. 73, Geoff LX2AO On May 01, 2012 at 15:23 +0200, Ken Alexander wrote: Many thanks for all the helpful responses! I do have many toroid cores in stock already but almost all are FT-50-xx and T-50-xx. I'll do the research and the math and give it a try when antenna building season arrives. It's still a little too cold and wet for that at the moment. 73 - Ken ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
