You might try playing around with the calculator on this web page: http://coil32.net/online-calculators/ferrite-rod-calculator.html I used #8 wire as an approximation to 2 - #10's and came up with 174 uH. Jim, K7JEB On 9/2/2018 2:11 PM, Wilson Lamb wrote: > My magnetics training is lacking (absent> and I'm short on time right now, so help is requested.