RU540U1 - Preselector for electronic range changing receiver - Google Patents

Abstract

A preselector for a receiver with electronic range switching, containing in each frequency range an inductor of a resonant input circuit connected to a common wire with one terminal and a radio frequency amplifier transistor emitter through a communication element, the collector of which is connected to one terminal of the resonant load circuit inductance, and the base of the transistor is connected through a capacitor to a common wire, characterized in that a resistor is introduced into each frequency range, connected with a base to a trans stories radio frequency amplifier of this range, the other - with the power terminal and the other terminal of the resonant circuit load another band inductor, a radio frequency amplifier transistor the collector of each band is connected to the corresponding output terminal, and the connection member is a coil.

Description

The proposed device relates to techniques for receiving information and can be used in radio receivers - portable and stationary broadcast receivers, in particular, automobile.

A well-known receiver with electronic range switching (see Belov NF Handbook on portable and car radios and radio tape recorders, M.: Radio and communication, 1992, p.205), the preselector of which contains a radio frequency amplifier, loaded on a resonant bypass filter . The switching of the ranges of long and medium waves is carried out by comm (utilization of the filter inductance coils by switching diodes.

The disadvantages of this device are low selectivity, low reliability and a rather high cost of the preselector, and therefore the receiver itself as a whole. All these drawbacks are due to the presence of two switching diodes, a sequence of 1) BUT in the device connected to the resonant circuit. ,, -. I

A well-known receiver with an electronic pen is f alla1 o ov (see

Belov N.F. Handbook of portable and car radios and radio tape recorders, M .: Radio and communication, 1992

which contains a radio frequency amplifier and in each wavelength range a resonant bypass filter. Long and medium wavelength ranges are switched by combining resonant bypass filters with switching diodes, which are connected in series with a filtered filter.

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through which it penetrates the filter of an unselected frequency range, which has a high resistance at the resonant frequency.

A well-known receiver with wide range switching (see Kuzinets L.M., Sokolov BC fsMW and TV units, Directory, M.: Radio and Communications, 1990, p. SCHK whose selector is closest to the proposed device, which allowed to receive it The preselector contains two frequency ranges, each of which includes a resonant input-frequency EHF circuit, a resonant radio frequency amplifier, an element (a shmi, integrated in the form of a capacitor, a resonant load circuit of a radio frequency amplifier, a switching diode with elements defining it Mode of operation, power output terminal and an output terminal.

This device operates as follows. A supply voltage is applied to the power terminal of the selected frequency range, under which the transistor of the radio frequency amplifier of this range enters the active mode of amplification of the signal from the input circuit, and the switching diode switches and passes the signal of the radio frequency amplifier to the output terminal. At the same time, the power terminal of an unselected frequency range is surrounded by | 1a, the transistor of its radio frequency amplifier and the switching diode ea "r" and prevent the signal from passing from the input circuit to the output terminal.

The closest analogue has the following disadvantages: low voter-.

at high frequencies, due to an increase in the conductivity of the switching diode and transistor of the non-vibrational frequency range, when the resonant circuits have a high transmission coefficient at its resonant frequency, low reliability due to the noise in the device of the switching diode with elements that specify its mode, operating with a large by the coefficient n "of the load, this also determines the high cost of the device and its complexity.

pa in each range and communication with them, in the proposed device, higher reliability and selectivity are achieved with lower material costs and the assembly and implementation of the device as a whole.

The essence of a useful medael is as follows. Into a preselector of a receiver with electronic range switching, which includes two frequency ranges, each of which contains an inductor of a resonant input circuit, connected to an ohmic wire with one output, and a second communication element with an emitter of an amplifier transistor radio frequency, the collector of which is connected to one output Inductors of the resonance circuit of the load, and the base of the transistor is connected via a capacitor to a common wire, are introduced through a single resistor into the naipidEt frequency range. One terminal of each resistor is connected to the base of the transistor, and its second terminal is connected to the power terminal and one of the terminals of the inductance output coil of the resonant load circuit of a different frequency range. The communication element between the resonant input circuit and the resonant radio frequency amplifier is made in the form of an inductor. The collector of the transistor of the resonant amplifier of the radio frequency of each range is connected directly to the power terminal of its range.

The figure shows the proposed preselector for a receiver with electronic range switching.

The preselector has two frequency ranges I, 2, each of which contains an inductor 3 of a resonant input circuit 4, with one output a coil 3 connected to an ohmic wire, and the other with one output of a coupling element 5, B1 | which is connected to the emitter of the transistor 6 of the radio frequency amplifier 7, the collector of the transistor 6 is connected to one output of the inductor 8 of the resonant load circuit 9 and the output terminal 10. The second input of the coil 8 is connected to the power terminal II.

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range, and the second conclusion, with kyavmma food II of a different range tjacTOT.

The proposed preselector operates as follows. In the selected frequency range, a voltage is applied to the power terminal II, which feeds the power to the radio frequency amplifier 7 through a circuit consisting of series-connected elements: coil 8, transistor b of the radio frequency amplifier 7, coil 5, coil 3. In this case, the transistor b is in gain mode. The signal from the input circuit 4 to the emitter of the transistor b is amplified due to the high resistance of the resonance coiture 9 at the resonant frequency, and is fed to the output terminal at 10 of the selected range of the preselector.

In the unselected frequency range, voltage is not supplied to its power terminal II, and the foit in the collector-emitter circuit of the transistor b of the radio frequency amplifier 7 does not flow. But from the power terminal II of the selected frequency range, a current flows through the resistor 12 - the emitter of the transistor b of the radio frequency amplifier 7, under which the transistor b is put into standby mode and bypasses the resonant circuit 9. The signal passing through the circuit: resonant input circuit 4, coil 5, transistor b, output terminal 10, is weakened due to its short circuit through transistor b to capacitor 13 by 0 (wire, and the high resistance of the circuit 9 at the resonant frequency is shunted by transistor b.

The exclusion from the scheme of the proposed chair of expensive diodes with elements that infect their mode allowed us to create a device with good selectivity, higher reliability, a simplified process of assembly of the product, significantly lower cost as the preselector, and the entire receiver as a whole.

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Claims (1)

A preselector for a receiver with electronic range switching, containing in each frequency range an inductor of a resonant input circuit connected to a common wire with one terminal and a radio frequency amplifier transistor emitter through a communication element, the collector of which is connected to one terminal of the resonant load circuit inductance, and the base of the transistor is connected through a capacitor to a common wire, characterized in that a resistor is introduced into each frequency range, connected with a base to a trans stories radio frequency amplifier of this range, the other - with the power terminal and the other terminal of the resonant circuit load another band inductor, a radio frequency amplifier transistor the collector of each band is connected to the corresponding output terminal, and the connection member is a coil.