|
|
|
|
[Medhurst 1947]
"H. F. Resistance and Self-Capacitance of Single-Layer
Solenoids." [Rosa 1908] "The Self and Mutual Inductances of Linear Conductors." [see also "Inductance of a Straight Wire", by Tim Healy]. |
[15] Radio
Designer's Handbook, Ed. Fritz Langford-Smith. 4th edition.
4th impression (with addenda), Iliffe Publ. 1957 [A later reprint
exists (1967) ISBN 0 7506 36351] Chapter 11: Design of radio Frequency Inductors. Section 11.2 (ii), p451: Medhurst's formula. Section 11.5: Short-Wave Coils [uses SWG wire sizes, but SWG diameters in mils (1 mil=0.001"=25.4 μm) are given in section 38.19, p1409.]. [Erratum: In chapter 36, Design of FM receivers, by E Watkinson: Rosa's formula for the inductance of a wire has been transcribed incorrectly, and the subsequent example on p1287 is incorrect.]. [16] "Optimum Wire Size for RF Coils", Charles J Michaels, W7XC, QEX, Aug 1987, p6-7. Skin effect: Ferromagnetic materials make poor RF conductors. The higher the conductivity, the thinner the skin, thus the advantages of using silver over copper is not as great as the ratio of their conductivities might suggest. [states incorrectly that silver has a slight advantage over copper because its surface corrosion products are conductive, whereas those of copper are not]. For a given coil form: if the wire is too thin the RF resistance will be large, if the wire is too thick, the proximity effect will be large. Therefore there is an optimum wire size for every coil form. Gives Butterworth's formula for optimum wire diameter: dopt=la/N, where a is a fudge parameter depending on the l/D ratio of the coil (a=0.615 for l/D=1). Advises against using hard-drawn copper for high Q coils. [17] "How Long is L?", Ian Hickman, Electronics World, May 1999 p386-389. Discussion of inductance, mutual inductance, inductance of a wire. [18] Radio-Frequency Measurements by Bridge and Resonance Methods, L. Hartshorn (Principal Scientific Officer, British National Physical Laboratory), Chapman & Hall, 1940 (Vol. X of "Monographs on Electrical Engineering", ed. H P Young). 3rd imp. 1942. Ch V1, section 4: The guard ring. Ch VI, section 6, Table II: Properties of Insulating Materials. Ch VIII, section 3: Inductance of single turn loop. [19] Inductance Calculations: Working Formulas and Tables, F W Grover, 1946 and 1973. Dover Phoenix Edition 2004. ISBN: 0-486-49577-9. [20] "Resistor Measurements", Bob Botos [of Hewlett-Packard], Electronic Product Design, July 1981, p89-93. Resistance of carbon resistors (film and slug types) decreases with frequency - "Boella Effect" caused by shunting by distributed capacitance of dielectric binder. Effect is greater for higher value resistors. C film resistors have less capacitance than slug types, 0.2-0.5pF for ½W RF types. Precision wirewound: pi-section and Ayrton-Perry non-inductive winding. Reactance of ordinary (inductive) wirewound resistors. Metal-film resistors: principal parasitic is capacitance, 0.2-0.6pF. Resistor model and ESR. Resistor measurements. [21] "PEP Wattmeter" Thomas V Cefalo WA1SPI, Ham Radio, Oct 1989 p76-80. Introduction dispenses with the idea of resistive voltage sampling by giving impedance analyser measurements of a 10KΩ carbon composition resistor. |
[51] "Coppers for Electrical Purposes", V A Callcut, IEE Proc. Vol. 133, Pt. A, No. 4, June 1986. |
|
|
|
|