Homemade directional couplers for cable TV. Scheme, description

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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
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Homemade directional couplers for cable TV. Encyclopedia of radio electronics and electrical engineering

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Encyclopedia of radio electronics and electrical engineering / Antenna amplifiers

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I decided to remake my three-program cable network, and instead of connecting houses in series with many house amplifiers (powered by direct current through the mains), make 3 powerful amplifiers (1 watt each). It was supposed to distribute the signal to houses and entrances with the help of directional couplers. With the collapse of the Union, the network collapsed for economic reasons (with 500 subscribers, the fee collected did not cover taxes and rental of cassettes). But the descriptions of these couplers, due to their extreme simplicity, may be useful to someone.

1. Coupler for 3

(click to enlarge)

The coupler for 3 is made on the basis of a 220 mm piece of RK-150-7-31 cable, from which the spiral central vein has been removed. Instead, four single-core conductors in insulation twisted into a bundle are threaded. The ends of the conductors are loaded with resistances of 75 ohms. and their beginnings (in the same place as the entrance) are connected to the main cables. The frequency response of the coupler is approximately the mirror of the attenuation in the cable, which ensures the equality of the signals on the channels at the output of the trunk.

2. Coupler for 2 with maximum connection

Homemade directional couplers for cable TV. Coupler for 2

This and all subsequent couplers are built with the desire to obtain the highest possible output signal, in the channels used, with a good IPM. Their frequency is suitable for intra-house distribution. Please note that the length of the base is increased to 410 mm.

3. Coupler for 3 intrahouse

It is made similarly to the 2-way output, but without the capacitor C1. All cores with a diameter of 0,4 mm (insulation 1,0 mm), curl pitch 15 mm. U taps = -10,5 dB, U transmitted = -3,5 dB (at the highest frequency). KBV = 1/0,84/0,75 in channels 2/4/6.

4. Coupler for 4 intrahouse

It is made similarly to a 2-way output, without capacitor C1, the load of the central core is 56 Ohm. All cores with a diameter of 0,4 mm (insulation 1,0 mm), curl pitch 15 mm. U taps = -12 dB, U transmitted = -4 dB (at the highest frequency). KBV = 0,82/0,91/0,71 in channels 2/4/6.

Author: E.Shustikov, UO5OHX ex RO5OWG; Publication: shustikov.by.ru

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