Given two air-wound coils mounted concentrically . . . the shorter outer coil is centered length-wise over the longer inner coil . . . all the dimensions such as coil diameters, lengths and turns per
Of course, F. W. Grover figured this out a century ago. Grover, "Formulas and tables for the calculation of mutual and self inductance", NBS Paper 169, 1912. (NBS is now NIST) Grover, "Tables for the
Hi Rick, Thanks for the info, I thought the methodology existed but didn't immediately find it. Appreciate the offer to scan and send but I don't think it will be necessary. Jim Lux, in an off-reflec
Hi Steve If you could find some old ARRL handbooks from back in the 40's, there is lots of information there about link coupling antenna tuners. Most of the transmitters back then used link coupling
Thanks Tom. I do have a couple of ARRL Antenna Books from the 1950's and there's a good bit of info in them. Also on L. B. Cebik's web site. I'll keep an eye out for the vintage handbooks you suggest
FWIW, when it comes to very precise calculations of L and C for air cored coils and transformers, the tesla coil folks have done a lot of work in the couple or 5 years on coming up with FEM models an
<I don't have a ready way to measure the inductance of each coil > Did you look at this month's QST? You can build what you need to measure this for less than a buck 73 W9OY _________________________
October? What page? _______________________________________________ See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather Stations", and lot's more. Call Toll Free, 1-800-33
The article starts on page 36, "A Low Cost Automatic Impedance Bridge", and describes using a sound card as an impedance bridge. It's an excellent example of using the computational power in a PC and
That's true. It's an audio frequency measurement system. We couldn't possibly use it to determine Q of an RF coil. It will also have errors that could be pretty large in some cases when reading reac
It is true the measurement is at audio freq, and it will not be the equivalent of a HP phase gain meter, or a VNA or other such device. For 160M, it will be better than determining inductance by (R^2
You can do a LOT better than the Wheeler equation these days, and the software is free. Sure, but 2MHz is a long way from 1 kHz, and 30MHz is even more so.. not that some sliding around of the taps w
I'm glad someone beside myself noticed that article. The LCR meter is worth several years subscriptions to me. de Paul, W8AEF _______________________________________________ See: http://www.mscompute