US1976574A - Radioreceiver - Google Patents

Description

@et 9, 1934.. E, FALKENTHAL RADI ORECE IVER Filed F'Sb- 20, 1951 2 Sheets-Sheet l- INVENTR H'TOWNEY 0ct. 9, 1934. E. FALKENTHAL RADIORECEIVER Filed Feb. 20, 1951 2 Sheets-Sheet 2 mmmmw .1nd www www www www Patented Oct. 9, 1934 PATENT GFFICE BADIORECEIVER Erwin Falkenthal, Berlin-Dahlem, Germany, as-

signor, bymesne assignments, to Radio Patents Corporation, New York, N. Y., a. corporation of New York Application February 20, 1931, Serial No. 517,235 In Germany -June 22, 1930 15 Claims.

This invention refers to means for receiving radio signals and more particularly to receivers operating according to the super-heterodyne principle.

The object of the invention is to provide means for receiving a broad lband of radio signal frequencies with the use of a minimum of apparatus and operating elements.

A more specific object of the invention is to provide means in a super-heterodyne radio receiver whereby the receiver may be used for receiving an extended band of radio frequencies such as the short wave and long wave range.

A further object of the invention is to provide means in a super-heterodyne receiving system for receiving radio frequency energy, whereby for the short waves a harmonic frequency of the local oscillator is utilized as a beat frequency and whereby for the long wave lengths the funda.- mental frequency of the local oscillator serves to produce an intermediate or beat frequency for which the receiver is designed.

These and further objects of the invention will become more apparent by the ensuing detailed description of the invention, which is taken with reference to the accompanying drawings, in which one embodiment of the invention is shown for illustration.

Figure 1 shows in a schematic way a circuit diagram of a short and long wave receiver embodying the invention.

Figure 2 illustrates in detail an adjusting dial scale to be used in accordance with Figure 1.

Figure 3 shows the same circuit -according to Figure 1 in one form of practical arrangement.

Similar reference characters designate similar parts throughout the different views of the drawings.

Referring to Figure 1, a receiving circuit in accordance with the invention is illustrated, the portions being non-essential to the invention having been omitted, or having been merely indic-ated, for clearness. The circuit shown is one of the well-known super-heterodyne circuits, also known as tropadyne circuit, in which the receiving circuit is connected to a tap point of the grid inductance coil and the cathode of 'the auxiliary oscillator tube, whereas the free end of the circuit is connected to the cathode across a resistance for the production of the auxiliary beat frequency. AE represents an antenna earth system for collecting incoming radio waves. A set of antenna tuning and coupling coils a1, in the example shown six coils, comprising the entire receiving range from 25 meters to 3000 meters is (Cl. Z50-20) provided with switching means, including switch arms S1 and S2, whereby the coils may be selectively inserted in the antenna path. A substantially identical set of secondary coils a2 is arranged to cooperate with the corresponding primary coils al and also provided with contacts and a switch arm S3 for successive connection. A variable condenser CA serves for tuning the secondary circuit to the frequency of the incoming waves received in the antenna circuit. Switch arms s1, s2 and s3 may be mechanically coupled, such yas on a comomnl shaft, (as shown in Figure 3) whereby corresponding primary and secondary coils may be connected in circuit in succession for receiving a signal within any desired wave range. The thus received signal is applied through coupling condensers Cc to the grid of a vacuum tube R1 which serves, at the same time, as a local oscillator for producing a beating frequency. For this purpose, the tube is provided with oscillating grid and anode circuits which are`inductively coupled with each other to provide the necessary `feed back for the productionof local oscillations. Referring to the primary and secondary set of tuning coils a1 and a2 respectively, the first three (left hand) coils of each set comprise the range commonly .known as short wave range extending from 25 to 200 meters wave length and the remaining three coils cover the Wave range from 200 to 3000 meters, known as long waves. cal oscillator is provided with three coils only, covering the long waves or low frequencies, in such a manner that for receiving the short waves a harmonic .frequency of the fundamental oscillator frequency is available to produce a definite intermediate or beat frequency for which the intermediate amplifier connected to the output of the tube 1 and comprises in the example shown, three stages of tubes R2, R3 and R4 is specifically designed. The oscillator coils in the grid circuit are shown at g and are primarily designed to operate for the long wave range from 200 to 3000 meters and the corresponding feed back coils r are similarly designed for covering the same Wave range. Thus, for receiving the three long wave ranges 1000 to 3000, 500 to 1000, and 200 to 500 meters, a separate coil is inserted in the antenna circuit, the secondary circuit, the oscillator circuit and the feed back circuit, whereas for receiving the short wave ranges 100 to 200, 50 to 100 and 25 to 50 meters, separate coils are connected in the antenna and secondary circuit only, whereas in the oscillator and feed back cirf cuit the last coils of the long waves corresponding According to the invention, the 1o-` to the lowermost range of the long waves-in the figure lthe left hand coils of the sets g and r respectively covering the range of 200 to 500 meters-are used for the reception of the entire short wave band. Switches sa, s5, s6, s7 and $8 are provided for inserting the oscillator and feed back coils, these switches being preferably coupled with switches s1, s2, s3, such as by mounting on a common shaft, to provide single control of the entire receiver as shown in Figure 3. The frequency of the local oscillator may be varied by means of the variable condenser Ca.

In this manner a receiver may be usedfor the entire radio wave band covering short and long waves, as from 25 to 3000 meters in the same and simple manner as an ordinary receiver designed for a restricted wave band is operated. Such all-wave receivers are required in a great many instances, such as in commercial radio telegraph stations, in stations for marine purposes and the like. Once the wave range switch has been set tothe desired wave band within which a signal is to be received, the tuning condenser CA and the oscillating condenser CR have to |be adjusted to produce a definite beat note in the same manner as in the case of any ordinary super-heterodyne receiver.

In order to insure efficient and easy operation of a receiver as described, a different intermediate or beat frequency is preferably u'sed for the long Wave and the short wave range of reception. In order to secure favorable results, the intermediate frequency for the long wave range should be smaller than the intermediate frequency for short wave range. The change from one intermediate frequency to the other intermediate frequency at the transition from the range of long wave to the'range of short wavey reception, 'or vice versa, may be accomplished either separately, such as by readjusting the intermediate frequency tuning condensers C1 in the` grid circuits of the tubes R2, R3, and R4.

When a separate adjustment of the intermediate frequency is used, it is preferable to designate the long and short wave range on the adjusting dial, such as shown by Figure 2. For this purpose the scales on the adjusting diald for the short and long wave range may, for instance, have different colors so that the operator, Whenever he changes from one to the other range, is at once apprised of the necessity of readjusting the intermediate frequency tuning condensers C1 from position I corresponding to one intermediate frequency to position II corresponding to the other intermediate frequency. In the example according to Figure 1 the intermediate frequency amplifier is shown to comprise two amplifying stages and one detector stage with a telephone T or a similar translating device in the output of the detector for the reception of the signal, but it is obvious that any kind of intermediate frequency amplifier may be used and that the detector stage may be followed by a low frequency or audio frequency amplifier, in accordance with the established practice.

In Figure 3 the schematic circuit according to Figure l has been shown in one form of practical arrangement, in which the. different sets of coils 4connected to the contacts are operated by common switch arm. From this figure it is seen that,

-with regard to the coils g and r, the cooperating switch arms s4, S5, s6, $7 and a8 i-lrst slide over contacts for inserting the first two coilswhereas the third coils are connectedto contact rails, whereby with the three last receiving ranges coris subject to many1 modifications and embodiments coming within its broad spirit and comprehensive scope, as set forth in the appended claims.

What I claim is:-

1. In asuper-heterodyne receiver, a tunable input circuit including a set of inductance coils, part of said coils covering the short wave range of signal frequencies and the remaining .part

covering the long wave range of signal frequencies, means to selectively connect said coils in said circuit, a local oscillator having a tunable oscillating circuit for adjusting the beating frequency and including a set of inductance coils corresponding to said first coils for the long wave range of signal frequencies, means to selectively connect said last mentioned coils in said oscillator circuit, and further means whereby for the reception of short wave signals, a harmonic component of said oscillator is used as a beating oscillation ,for producing a beat frequency different from the beat frequency produced by the long wave signals ,and the fundamental componen of said local oscillator.

2. In a super-heterodyne radio receiver, an antenna circuit, a set of inductance coils, part of 1 said coils covering successive sections of the short wave range of signal frequencies and the remaining part covering successive sections of the long Wave range of signal frequencies, means for selectively connecting said coils in said antenna circuit, a tunable secondary circuit cooperating with said antenna circuit and including a second set of coupling coils corresponding to and cooperating with said first set of coils, a local vacuum tube oscillator having an oscillating circuit and a regenerative means for producing continuous oscillations, said oscillating circuit comprising a set of inductance coils to be selectively connected for producing a wave range of local oscillations corresponding to said range of long wave signal frequencies, and circuit means for said secondary circuit and said local oscillator whereby a definite beat frequency is produced by long wave signals in combination with the fundamental component ofsaid local oscillator and whereby a beat frequency different from and higher than said rst beat frequency is produced by combination of the short wave signal oscillations with a harmcnic component of said local oscillator.

3. In a super-heterodyne receiver as described in claim 2, in which a common operating element is provided for the connection of corresponding inductance coils in the antenna, secondary and oscillator circuits, and in which the coil in the oscillator circuit covering the lowermost section of the long wave range of signal frequencies serves for the production of local oscillations for heterodyning the short wave signal frequencies.

4. In a super-heterodyne radio receiver, an antenna circuit, a set of antenna loading coils, part of said coils covering successive sections of the short wave range of signalling frequencies and the remaining part covering the long wave range of signalling frequencies, means for selectively connecting said coils in said antenna. circuit, a tunable secondary circuit cooperating with said antenna circuit and including a second set of inductance coils corresponding to and cooperating with said iirst set of inductance coils, means for selectively connecting said last mentioned coils in said secondary circuit, a local vacuum tube beating oscillator having an oscillating circuit and regenerative means for producing continuous oscillations, said oscillating circuit and said regenerative means comprising each a set of inductance coils to be selectively connected for producing a wave range of local oscillations for receiving said long wave signal frequencies, circuit means for said secondary circuit, said local oscillator and said regenerative means whereby a definite beat frequency is produced by long wave signals in combination with the fundamental component of said local oscillator and whereby a beat frequency dierent from and higher than said first beat frequency is produced by combination of short wave signal oscillations with a harmonic component of said local oscillator and a selective intermediate frequency amplifier with selectivity control means for changing from the one to the other of said beat frequencies.

5. In a super-heterodyne receiver as described in claim 4, in which a common operating element is provided for the connection of corresponding inductance coils in the antenna, secondary and oscillator circuits, and in which the coil in the oscillator circuit covering the lowermost long wave section serves for the production of the local oscillations, a harmonic of which is used for heterodyning the short Wave signal frequencies.

6. In combination with a superheterodyne receiver comprising means for receiving incoming oscillations within a predetermined frequency band, a generator for producing local oscillations of varying frequency for producing an intermediate beat frequency With the lower-range of incoming oscillations, said local oscillations having higher harmonic components and means for utilizing the harmonic components for producing an intermediate beat frequency with the higher range of incoming oscillations.

'7. The method of radio reception over a broad wave length range of incoming signals comprising selecting a lower and an upper range of incoming signalling frequencies; generating local beating oscillations variable over a definite frequency range for receiving the lower range of incoming frequencies and receiving the upper range of incoming frequencies by beating with harmonic components of said local oscillations to derive a fixed intermediate beat frequency from the incoming signalling frequencies and the local beating frequencies, respectively.

8. The method of radio reception over a broad wave length range of incoming signals comprising selecting a lower and upper range of incoming signalling frequencies; generating local beating oscillations variable over a frequency range to derive a predetermined fixed intermediate frequency by beating with the lower range of incoming signalling frequencies and utilizing harmonic components of said local oscillations for beating with the upper range of incoming frequencies to derive a fixed intermediate frequency different from said rst intermediate frequency.

9. A system for radio reception comprising means for selecting and tuning an upper and lower range of incoming signalling frequencies; a local oscillator producinga variable frequency, means for combining the oscillations of said local oscillator with the lower range of said incoming signalling frequency for deriving a fixed intermediate beat frequency, said local oscillator being designed to produce harmonic frequencies of its fundamental frequency; and means for combining said upper range of receiving frequencies with said harmonic frequencies of said local oscillator for deriving a xed intermediate beat frequency.

10. A system for radio reception comprising means including a receiving circuit for selectively receiving and tuning an upper and lower range of incoming signalling frequencies; a local oscillator producing a variable frequency having both fundamental and harmonic components; means for combining said lower range of receiving frequencies with the fundamental frequency and for combining said upper range of receiving frequencies with a harmonic component of said local oscillator for deriving a iixed intermediate beat frequency.

11. In a superheterodyne receiver, a tunable input circuit including a set of inductance coils, part of said coils covering the short wave range of signalling frequencies. and the remaining part covering the long wave range of signalling frequencies; means for selectively connecting said coils in said circuit; a local oscillator having a tunable oscillating circuit for adjusting the/beating frequency and including a set of inductance coils corresponding to said first coils for the long said oscillating circuit; and further means whereby for the reception of short wave signals a harmonic component of said oscillator is used as a beating oscillation for producing a predetermined xed intermediate beat frequency.

12. In a superheterodyne receiver comprising a circuit for receiving incoming signalling frequencies, said circuit including tuning means for both gradual and step-by-step variation to provide a set of tuning ranges covering both lower and higher receiving frequencies; means for selecting said tuning ranges;` a local oscillator having a tunable oscillating circuit for adjusting the beating 'cfrequency including fundamental and harmonic components; and means whereby said oscillator is used for receiving both said higher and lower receiving ranges by beating the lower range'of said receiving frequencies with a fundamental component and by beating the higher range of the receiving frequencies with a harmonic component of said local oscillator to derive a fixed intermediate beat frequency.

13. In a superheterodyne receiver comprising means for receiving incoming signalling frequencies varying over a predetermined range; means for producing local beating oscillations variable over a range substantially smaller than the range of incoming signalling frequencies for deriving a fixed intermediate beat frequency in combination with the lower portion of incoming frequencies, said local oscillator producing harmonic components of its fundamental frequency; and means for receiving theupper portion of incoming signalling frequencies by beating with the harmonic component of said oscillator to derive a predetermined xed beat frequency.

14. In a superheterodyne system; an antenna circuit for receiving incoming signals: a plurality of first separate tuning coils each adapted to tune the receiving circuit over a different range of frequencies; rst switching means for selectively connecting said coils to said antenna circuit for receiving the predetermined range of frequencies of the connected coil; alocal oscillator comprising an electron tube having an input and output circuit; a receiver connected to said output circuit for receiving beat notes at a predetermined frequency; a plurality of second separate tunable coils similar to said first coils and each adapted to tune the local oscillator over a frequency range corresponding to that of the respective said first coils for producing therewith the beat frequency ofsaid receiver; second switching means for selectively connecting said second coils to the input and output of said tube; means for coupling said antenna circuit to said input circuit and means whereby said first and second switching means are jointly operated for connecting the corresponding coil of said first coils with the antenna circuit and for connecting the corresponding coil of said second-mentioned coils with the input circuit.

15. In a superheterodyne system; a receiving circuit for receiving incoming signals; a pluralityl of separate tuning coils each adapted to tune said receiving circuit over a different range of frequencies; iirst switching means for selectively connecting said coils to said receiving circuit for receiving a desired range of frequencies; a local oscillator comprising an electron tube having an input and output circuit; a coupling means for applying incoming oscillations from said receiving circuit to said electron tube for combining with the local oscillations; a receiver connected to said output circuit for receiving beat notes of a predetermined frequency; a plurality of second separate tuning coils similar to said first coils and each adapted tov tune said local oscillator over a frequency range corresponding to the frequency ranges of said iirst coils for producing therewith the beat frequency of said receiver; second ,switching means for selectively connecting said second coils to said oscillator; and means whereby said first and second switching means are jointly operated.

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