Both have a 7.1-MHz center frequency and a 200-kHz bandwidth. Both filters are designed to be doublyterminated, with 50 Ω at input and output. The dashed plot shows the performance of a double-tuned circuit filter. The solid-line plot shows gain versus frequency for a single-tuned circuit filter. I'll examine the fundamentals of the double-tuned circuit by describing the 40-m filter shown in Figs 1 and 2. (A computer generated the data for this and the other graphs in this article experiment confirmed the data.) The gap between the filterresponse maxima and the 0-dB line represents' the filters' insertion loss. Both filters are adjusted for maximum response at 7.1 MHz. The solid curve shows the response of a single-tuned circuit the dashed curve, a double-tuned circuit. See text and Fig 2.įig 2 - An HF (7.1-MHz) double-tuned-circuit filter constructed for lab analysis.įig 3 - Analysis of the filter shown in Figs 1 and 2. This filter's variable coupling capacitor varies the filter response to illustrate concepts discussed in this article.) The tuned windings of T1 and T2 consist of 17 turns of #22 enameled wire on T-50-6 toroidal, powdered-iron cores the transformers' untuned links at first consisted of three turns of insulated wire but were later reduced to two turns. (There is usually no justification for using a variable coupling capacitor in practical double-tuned circuits for frequencies of 30 MHz and lower instead, use a fixed capacitor of the value required by the filter design. Cl and C2 are mica-dielectric compression trimmers C3 is an air-dielectric variable. Basic Characteristics of the Double-Tuned Circuitįig 1 - A double-tuned-circuit filter for 40 m. In it, I'll examine the double-tuned LC circuit from an experimental viewpoint, emphasizing measurement, evaluation, and adjustment. This tutorial emphasizes their universal properties. The result may be a circuit that does not meet the filtering goal.Īlthough HF double-tuned circuits differ greatly in physical appearance from those built for microwave frequencies, all double-tuned circuits share many similarities. Designing a double-tuned circuit for use at HF and below is not difficult,' yet builders commonly encoun ter practical difficulties in building and adjusting the double-tuned circuit, especially at VHF and above. The double-tuned circuit, among the most common filters found in radio equipment, consists of two tuned circuits, or resonators, that are coupled together, allowing energy in one to be shared with the other.
Double tuned filter designer how to#
Here's how to evaluate and adjust double-tuned circuits for maximum performance. Home - Techniek - Electronica - Radiotechniek - Radio amateur bladen - QST - The double-tuned Circuit: An experimenter's tutorialĪlthough the double-tuned circuit is popular with Amateur Radio experimenters, its response can sometimes be misleading.
0 kommentar(er)
