Production of common sense coil) x "L7 N (U) ^ 6 I5 q2 n4 D
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Benefits Q: Q, a quality factor of the coil is the coil inductance reactance (ie, AC resistance) at a specific frequency on the ratio of the coil loss resistance. This resistance component is the DC resistance and other losses (such as non-conductive material close to the coil inside the dielectric loss and conductor or the coil wire in the vicinity of its eddy current loss) of the total. High Q value of not only lead to better selectivity, but also to improve the impedance tuning circuit, so that detectors have a higher detection voltage. ; T "S * C8 G" x * M)); ~, u0 H
6 k9 o #) 9 W "S" f7 K manufacturing large coil: wire length and its associated loss increase is linear; inductance is increasing with the square of the diameter of the coil, the inductance for a specific increase coil diameter of the wire will be used less, thereby reducing wear and tear.
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So that the coil length and diameter of the same: in all other conditions being equal, the appearance of the coil ratio (the ratio of length to the diameter) impact of its Q-value. Length and diameter close to the point when there is a best. Do not use a long (more than twice the diameter) or very narrow (less than half the diameter) of the coil.
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6 W; g $? 4 M $ c (W) v /] 0 G turn away: so that the distance between the coil wire is not less than the diameter of wire. By a tightly wound coil eddy current losses of damage, because the adjacent wires in a wire into the surface of a strong magnetic field. ) H2 Z) b5 C "T # P4 n + j $ f6 N & j
4 D! P: H (N # ~% ~ 9 e thick wire: The most effective wire diameter. Litz wire (Litz Wire, that is braided series lines, stranded wire) with a large effective diameter, as it greater surface area. but not easy to find large number of shares and more Litz wire, and specific attention to the frequency range of different combinations of wire size and number of shares. For the broadcast band, the stock line 44 or 46, should the composition of thin . & a4 m% k * P b! p-g
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Types of wire: insulated wire easy to get the distance between the wires. Silver-plated PTFE insulated wire is almost the best (as far as I know, for reasons of chemical compatibility, and all are silver plated PTFE insulated wire). Bare copper wire until it is oxidized before the bad. Insulating material or coated with enamel helps oxidation. As the tin and lead is not good conductor, PVC insulated tinned wire is lossy. You can use tinned wire wound into a coil available, but difficult to Q values of more than 200.
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PVC pipe: This material is suitable for our purposes. I recently used on the 16th of PTFE insulated silver wire in 6.25 inches of green PVC pipe around a number of coils, measured Q values are easily more than 400. 1 x9 v) ~ 6 J * @ 0) $ p
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Coordination: As you increase the coil diameter, number of laps will be reduced, so to select the appropriate wire size and spacing in order to maintain the ratio of coil length and diameter of close to 1:1. And remember coil needs and other major parts radio 2 to 3 separate diameter distance. In order to achieve high-Q coil favorable conditions, you also need low loss capacitors. Like most transistor radios inside the polyethylene components, common components are phenolic insulator undesirable. Looking for ceramic or glass insulator capacitors. The only real solution is to pay attention to saving money second-hand stalls radio. . D 'Q * E8 S7? "F5 d ^
+ V "X / K # b & R, ~ u '[Z ferrite cores: ferrite allows you to make cheap and have the appropriate Q value (200 or more) of the small coil. Magnetic coil is self-shielding, Therefore, the overall arrangement is not strictly required. mixtures of different ferrite materials tailored to specific purposes and the frequency range. some of this type of material but actually for the consumption of high-frequency. Feiwu box of ferrite is most certainly not apply the mixture. can be ordered from bytemark.com Amidon mix 61 cores, FT-82-61 is a good option. at the same site can get hypothermia electromagnetic wire, do not need to scrape paint, but welding! AM radio antenna bar magnet is a good way to solve the problem.
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