Topband: Info on Common mode chokes

[Carol Richards]

Hello....

I am hoping to make a common mode choke to use with my inverted L ( 90 feet vertical   45 feet horizontal). From the various discussions on this reflector, it was suggested that 5 toroid cores, # 31 mix with 7 turns of RG 213 should be what I need. I called FAIR RITE and the largest cores they have are 2.4" X 1.4" X 1/2", but the tech support person wasn't sure of the part number I needed. He also scratched his head when I told him I needed the choke for 1.8 mhz and plan to run legal limit. Has anyone built a common mode choke and could be able to give me a more definitive answer as to part number or a better design?


Carol