Hello Daniel: You should use 21 turns for L17 as specified in the manual.
The inductance formulas and charts are approximations based on typical samples of the toroid material. You can expect some variation in the actual value, such as what you note with the charts in link saying to us 22 turns instead of 21 turns for L17 (2.50μH). Similarly, trying to measure the inductance will lead to variations based on the calibration of the inductance meter at the specific value being measured. The circuits were designed and tested with the numbers of turns and core types specified. Part of the design is to provide optimal performance over the range of inductances you'll find with various core samples, as long as you use the type of core specified, the correct wire and the correct number of turns positioned as shown in the illustrations! That's why there's a note on page 54 that says: "In the following steps you'll install several toroidal inductors. Use the number of turns indicated. Do not attempt to alter the turns to match inductances specified in the parts list." Ron AC7AC -----Original Message----- Hi, L17 is one of the toroids in the 80 low pass filters. It is a T44-2 with 21 turns (p 70 in the manual). This will have 2.26 uH, at least if WA8MCQ is right (see http://www.retards.org/library/technology/electronics/toroids/toroidcharts_m cq.htm ). But on page 5 of Appendix A, L17 is listed as 2.50 uH (part no E680012). Is that a typo? Or is that correct, and L17 needs 22 turns, which would make 2.52 uH? 73 Daniel M0ERA K3 #4271 -- Daniel, M0ERA, Oxted, Surrey _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
