CN1089768A - Wideband amplifier for TV antenna - Google Patents

Abstract

The invention discloses a kind of wideband amplifier for TV antenna that is installed in the television receiving antenna back.Its amplifier element was finished with being connected by separable conductive component of circuit, after amplifier element disconnects, coupling element is connected signal again by separable conductive component, thereby regulated gain, solved the problem that the signal to noise ratio that antenna amplifier antennafire causes in the prior art, Maximum Output Level worsen when reducing gain significantly.The TV user that it can be used for various places improves reception, increases to receive platform quantity.

Description

Wideband amplifier for TV antenna

The present invention relates to a kind of wideband amplifier for TV antenna that is contained in the television receiving antenna back.

Wideband amplifier for TV antenna of the prior art (hereinafter to be referred as antenna amplifier antennafire), for adapting to the situation that various places user's acceptance point intensity of TV signal varies and may change, avoid because forceful electric power is looked signal and made antenna amplifier antennafire or television set enter the blasting state, some antenna amplifier antennafire is designed to Gain Adjustable.1989 the 12nd interim " introducing three kinds of low noise TV antenna booster " literary compositions of " radio " magazine disclose the antenna amplifier antennafire that a kind of Gain Adjustable saves, it is the overall gain that changes certain frequency range by gain-adjusted potentiometer that adjusting has an attenuation, when forceful electric power is looked signal and reduced overall gain, the signal to noise ratio that antenna amplifier antennafire is looked signal to light current will worsen.All-channel low-level amplifier one literary composition of 129 pages of narrations of Dong's book pendant " common antenna TV system " book of showing that the People's Telecon Publishing House publishes in August, 1984, a kind of method of regulating gain by the mode of regulating the triode quiescent point is disclosed, but this dynamic range that triode is amplified reduces, promptly reduced its Maximum Output Level, and this mode also is difficult for obtaining the gain adjustment of wide range.

Task of the present invention provides a kind of wideband amplifier for TV antenna, and it not only can regulate gain in the scope significantly, and can avoid owing to reduce the deterioration of the caused signal to noise ratio of gain, Maximum Output Level significantly.

For solving above-mentioned task, the present invention finishes the amplifier element of antenna amplifier antennafire with being connected by separable conductive component of circuit, one end of separable conductive component and the fixed contact of circuit join respectively, the other end and amplifier element or coupling element join respectively, after amplifier element and amplifying circuit disconnection, can be at the signal breakpoint place of amplifying circuit connection signal coupling element.Like this, that one-level amplifying circuit that disconnects amplifier element does not participate in amplifying, and the TV signal of interruption is connected by signal coupling element, if disconnect some levels or whole amplifier element again, then can regulate overall gain in wide range or not have gain.Because the process of above-mentioned adjusting gain is the process that amplification is withdrawed from some grades of amplifications, neither sets up signal attenuation circuit, does not change the quiescent point of all the other amplifying circuits again, so can not cause the deterioration of signal to noise ratio and Maximum Output Level.

Amplifier element of the present invention or coupling element can be made into plug in construction with being connected of circuit, one end (as socket) of plug connector joins with the fixed electrical contact of circuit, the other end (as plug) joins respectively with amplifier element or coupling element, by the plug connector that plug amplifier element or coupling element are connected, can realize amplifying or the mutual conversion of couple state.

Being connected and can be made into change over switch formula structure of amplifier element of the present invention or coupling element and circuit.The break of change over switch and the fixed electrical contact of circuit join, and the movable contact of change over switch (as the travelling contact of circuit) joins respectively with amplifier element or coupling element, stirs change over switch, can realize the mutual conversion of magnifying state and couple state.

Owing to be to regulate what of number of stages of amplification in the above-mentioned solution to the adjusting essence of antenna amplifier antennafire overall gain, reducing overall gain is some grades of amplifications to be changed be enlarged into couple state, neither set up attenuator circuit, do not change the quiescent point of all the other amplifying circuits at different levels yet, so can not cause owing to reduction overall gain (particularly significantly) signal to noise ratio that causes, the deterioration of Maximum Output Level, and the wideest gain-adjusted scope (gaining to highest-gain from nothing) is arranged.Above-mentioned advantage can be brought following good effect again: it is very high that the gain of antenna amplifier antennafire can design, and can not use because the acceptance point signal is too strong and needn't worry the user, and the user can regulate voluntarily according to reception.This has just adapted to the various places intensity of TV signal well by place, time distribution ten minutes complicated situation, has strengthened the practicality of antenna amplifier antennafire greatly.In addition, the adjusting of gain only need be stirred change over switch or plug element, uses very convenient, reliable.

Below in conjunction with embodiment the present invention is described in further detail.

Fig. 1 is circuit theory diagrams of the present invention.

Fig. 2 is the used socket schematic diagram of amplifier element of the present invention or coupling element.

Fig. 3 is the schematic diagram of the socket core of Fig. 2.

Fig. 4 is the used plug schematic diagram of amplifier element of the present invention or coupling element.

Fig. 5 is a change over switch base portion schematic diagram of the present invention.

Fig. 6 is the cutaway view of change over switch of the present invention along shaft axis.

In circuit theory diagrams shown in Figure 1, it is the high pass filter of 40 megahertzes that capacitor C 1, C2 and inductance coil L1 constitute cut-off frequency.Resistance R 1, R2 are the biasing resistor of first order amplifying triode BG, resistance R 3, capacitor C 3 constitute the negative feedback branch road, the collector electrode inductance coil is L2, and resistance R 4, capacitor C 4 constitute the electric source filter circuit that the first order is amplified, and the output coupling capacitor that the first order is amplified is C5.Amplify by amplification circuit IC1, biasing resistor R5, filter capacitor C7 the second level, and coupling capacitance C6 constitutes.Power transformer B, high frequency choke coil L4, L3, filter capacitor C8, C9, C10, C11, C12, C13, circuit of three-terminal voltage-stabilizing integrated IC2, rectifier diode D, feeder line (2) is formed the voltage stabilizing DC power-supply circuit.The fixed electrical contact of circuit (4), (6), (9), (10), (12), (15), (17) join respectively with movable electric contact (5), (7), (8), (11), (13), (14), (16).

TV signal from antenna is imported from signal input part (1), after the amplifying circuit amplification of forming by triode BG, amplification circuit IC1 and peripheral circuit, pass through feeder line (2) again, output coupling capacitor C14, by output (3) output, this can obtain about 32 decibels overall gain at last; If triode BG is removed, between the fixed contact (4) of circuit, (9), connect a coupling element (as lead, electric capacity), this moment is amplification integrated block IC only ₁Participate in amplifying, can obtain about 20 decibels gain; If with amplification circuit IC ₁Remove, between the fixed contact (10) of circuit, (15), connect coupling element, can obtain about 12 decibels gain; If with triode BG and amplification circuit IC ₁Remove entirely, then do not have gain, only use as filter.

The socket (18) that the fixed electrical contact of circuit shown in Figure 1 (10), (12), (15), (17) can be produced on is as shown in Figure 2 gone up and is welded with the circuit respective point, fixed electrical contact (10) and remaining all can be made into shape shown in Figure 3, it can be formed by elastic sheet metal bending, and big or small Ying Yineng closely is fixed on insulation (as the plastics etc.) skeleton of socket (18) and is as the criterion.Movable electric contact (11) among Fig. 1, (13), (14), (16) can be fixed on the insulation framework of plug shown in Figure 4 (19), and its size, shape should be as the criterion with lucky insertion socket (18).Amplification circuit IC ₁Input, earth terminal, output, power positive end weld mutually with movable electric contact (11), (13), (14), (16) respectively.Coupling element (as electric capacity, lead) can be welded on the two relative electric contacts of another piece plug as shown in Figure 4.Like this, pull up amplification integrated block IC from socket (18) ₁The plug that is connected (19), another plug of plugging coupling element again and being connected just can realize that this grade amplification becomes coupled state by amplification.In addition, indicate on product that amplifying still is male part and slotting orientation.Fixed electrical contact among Fig. 1 (4), (6), (9) and movable electric contact (5), (7), (8) or being connected of coupling element can be with reference to said structures, and difference is to save an electric contact of socket.

Being connected and can be made into as shown in Figure 6 change over switch formula structure (the two pairs of electric contacts that only draw among Fig. 6 also have similar but two pairs of long electric contacts of relative distance do not draw in vertical direction) of the fixed electrical contact of circuit (4) among Fig. 1, (6), (9) and movable electric contact (5), (7), (8) or coupling element.Keep fixed electrical contact shown in Figure 5 (4), (6), (9) and silver-plated on the part of amplifying circuit printed board (20).Another electric contact that movable electric contact (5), (7), (8) and the coupling element that elastic conduction sheet metal (as silver-plated phosphorus bronze sheet etc.) is made used is fixed on the insulating trip (21) by rivet (22) and other three rivets.Screw (23) is pulled in insulating trip (21) between the part (20) of printed board rotationally, and insulating washer (24) makes both keep certain distance.At last, four pin of triode BG are welded in respectively on four rivets, the bipod that emitter is relative (emitter of 2SC3358 has bipod) will be welded in respectively on long two the relative rivets of relative distance.Like this, rotate change over switch and just can realize amplifying conversion with couple state, and when forwarding coupled state to (the relative bipod of emitter this moment is connected signal), movable electric contact (5), (8) relative distance are shorter, can not contact on the fixed electrical contact (6), prevent because the signal attenuation that the junction capacitance of triode BG causes.Also to mark the mark that amplifies and be coupled on the gear of change over switch.For the integrated circuit amplifier section, can copy aforesaid way, note two long movable contacts of the relative distance of change over switch should with amplification circuit IC ₁The welding mutually respectively of power positive end, earth terminal; Short two movable contacts of relative distance should with amplification circuit IC ₁Input, output welding mutually respectively, also will be at amplification circuit IC ₁Power positive end, earth terminal and connect a coupling capacitance.Like this, when the rotation change over switch makes it be in couple state (at this moment, the coupling capacitance of above-mentioned parallel connection is connected signal), amplification circuit IC ₁Input, output all be in the attitude that opens circuit, prevented the damage integrated circuit (IC) ₁Reach decay to signal.

Each component parameters of the foregoing description is as follows: resistance R 1, R2, R3, R4, R5 are respectively 51K Ω, 8.2K Ω, 360 Ω, 1K Ω, 430 Ω.Capacitor C 1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14 are respectively 51P, 51P, 3000P, 3000P, 200P, 200P, 6800P, 6800P, 220 μ, 220 μ, 6800P, 6800P, 6800P, 1000P.The number of turn of inductance coil L1, L2, L3, L4 is respectively 8,25,30,30 circles, they all with the enamelled wire in 0.5 millimeter in line footpath close on the cylinder of 4 millimeters of diameters tread flaking form.Triode BG can use 2SC3358.Amplification circuit IC1 can use μ PC1651.Three-terminal voltage-stabilizing ic chip 2 can be used 7812 of 12 volts of voltage stabilizings.Diode D can use IN4007.The coaxial TV feeder line of available 75 Ω of feeder line (2).Transformer B can use 220 volts of wattage transformers of 17 volts of secondary voltages.Coupling element can be used 200P as selecting electric capacity.

The present invention can do many variations, but they all do not depart from essence of the present invention.As: the number of stages of amplification of antenna amplifier antennafire can increase or reduce; Every grade of amplification can be designed to triode or integrated circuit structure arbitrarily; Also can be made into VHF separately (or again be divided into height two frequency ranges with VHF) amplify the structure of amplifying output in parallel again with another road UHF separately, with the independent gain of regulating VHF or uhf band; The high pass filter of antenna amplifier antennafire input can change band pass filter into or remove the back and replace with a coupling capacitance; The also available a bit of 75 Ω feeder lines of signal coupling element replace, the plug of burn-oning respectively at its two ends, the two plug core ground connection that shielding conductor connect of feeder line, two plug cores that heart yearn connect and two breakpoints of TV signal join respectively, thereby signal are connected (this mode can be used for because of disconnecting the some grades of signal breakpoints that amplify the large span that forms); Circuit can also be finished with other any separable conductive component with being connected of amplifier element or coupling element.

Claims (4)

1, a kind of wideband amplifier for TV antenna, comprise amplifier, dc power supply, it is characterized in that separable conductive component links together amplifier element or coupling element and circuit, one end of separable conductive component and the fixed contact of circuit join respectively, and the other end and amplifier element or coupling element join respectively.

2, wideband amplifier for TV antenna according to claim 1 is characterized in that separable conductive component can be made of plug connector.

3, wideband amplifier for TV antenna according to claim 1 is characterized in that separable conductive component can be made of change over switch.

4, according to claim 1 or 3 described wideband amplifier for TV antenna, the break that it is characterized in that change over switch is directly on circuit board, short a pair of of the relative and relative distance of four movable contacts of change over switch joins respectively with input, the output of amplifier element respectively, relative another to respectively with coupling element and amplifier element in addition two pin be in parallel.

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