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The E6 repeater is a low-cost, transistorized, voice-frequency, two-way repeater for use in the exchange area plant, including use in trunks between local offices and between local and toll offices. It permits both types of trunks to be operated at low net loss, while meeting the impedance requirements placed on trunks between local and toll offices. These features are possible because of a unique method of repeater design, in which the impedance-matching function and the gain function are allocated to separate portions of the repeater and are separately adjustable. The impedance-matching function is accomplished by means of a line building-out network, which permits any cable pair associated with the repeater to be built out and made to match the impedance of the toll office. The gain unit presents the same image impedance, which is essentially independent of gain adjustment. Changes in gain are controlled by two resistive, adjustable artworks — one in the series-connected negative impedance converter, and the other in the shunt-connected converter. In previous designs of negative impedance repeaters, complex impedance networks were required for adjustment of both gain and impedance match. The E6 repeater also incorporates novel mechanical features, with transistorization resulting in low power drain and less heat dissipation in the telephone central office. Power is derived from the existing 48-volt central office battery. |
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