Homebrew Your Own Inductors!（家酿自己的电感器!）.pdf

Homebrew Your Own Inductors! Can’t find the inductors you need for an antenna, a tuner or amplifier? Build your own—it’s easy! By Robert H. Johns, W3JIP Air-dielectric inductors can be made quite easily at home. Some coils are held together by clear epoxy ribs, others use scrap pieces of PC board and epoxy. The larger coils are made from 1/ -inch-diameter copper tubing. 4 Corrections to this article appear in October QST Feedback . Those favorites of do-it-yourselfer’s—Barker Williamson’s (BW) Miniductor and Air Dux coil stocks—are getting harder to find. When you do locate a source, you’ll find the inductors are rather expensive. Less-expensive inductors, such as those shown in the accompanying photographs, can be homemade, using epoxy for the supporting ribs. The coils have excellent Q—some even higher than those of shiny, tinned coils that are often used. [1, 2] Mounting posts to support the homemade coils on a chassis can be added as shown in Figure 1. I’ll tell you how you can produce similar inductors, make coil forms that easily release a tightly wound coil after wrapping and how to wind the coils with uniform turn spacing. August QST: Homebrew Your Own Inductors! - Page 1 ARRL 1997 QST/QEX/NCJ CD C i ht (C) 1997 b Th A i R di R l L I Figure 1—Mounting posts for these coils are made from flat-head nylon bolts attached to the coils with epoxy. For greater coil strength, rib-reinforcing strips made from PC board and perf-board can be used to further strengthen the inductor assembly. For these coils, I use magnet wire because the epoxy attaches firmly to the wire’s plastic coating. Bare copper wire can also be used, but its bond with the epoxy is not as strong. Coil Forms You’ll need some forms on which to wind the coils. Such forms are readil