just curious if anyone has ever built their own concentric coil for a teknetics mark 1. the smallest coil that will work good on a mark 1 is the six shooter coil made for a whites. i have never attempted to make a coil but would like to make one 4 inches in size for very trashy areas. the mark 1 operatinf frequency is 6.59khz if this helps. if anyone can help me with this i would appreciate it. let me know what you have and thanks for looking and happy hunting...