US2299337A - Arrangement for varying the band width in high frequency circuits - Google Patents

Description

O 20, 19424 w. MENNERICH ETAL 2,299,337 ARRANGEMENT FOR VARYING THE BAND WIDTH IN HIGH FREQUENCY CIRCUITS j Original Filed ual cn 26, 1937 mum;

Patented Oct. 20, 1942 ARRANGEMENT FOR VARYING THE BAND WIDTH IN HIGH FREQUENCY CIRCUITS Wilhelm Mennerich, Potsdam, Otto Siepke,

Berlin-Staaken, and Alexander Schaaf, Berlin- Charlottenburg, Germany; vested in The Alien Property Custodian Original application March 26, 1937, Serial No. 133,138. Divided and this application May 16, 1939, Serial No. 273,826.- In Germany.March Claims.

This application is a division of our copending application, Serial No. 133,138, filed March 26, 1937, entitled Arrangement for varying the bandwidth in high frequency circuits, which application has resulted in U. S. Patent No. 2,177,835, issued October 31, 1939.

Our invention relates to an arrangement for .varying the band width in high-frequency circuits.

Nowadays, it is frequently necessary, particularly in radio received apparatus to vary the band width of the tuning devices or of the band filters. This isaccomplished in a manner well known in the art by detuning the tuning circuits with respect to one another. For instance,

the band width of the circuit is adjusted and the degree of coupling or the inductance of the tuning coils remains the same. The width of the band width will nevertheless vary with tuning of the oscillatory circuits. While an oscillatory circuit may be adapted to be adjusted for tuning from one frequency band to another by adjustments of either the capacity or the inductance, it is usual to change the inductance for this purpose, inasmuch as this results in a simpler and less expensive arrangement. The band width of filters may be varied by the insertion of copper discs between coupled coils. The present invention uses a method which is particularly advantageous, if the oscillatory circuits of the tuning device are decoupled by the interposition of elements, such as tubes, and if the parts of the tuning device are placed in different containers.

According to the present invention an arrangement for varying the band width of tuning devices in high-frequency circuits, particularly with compressed iron powder cores, is provided,

preferably in the case of an inductive decoupling of the tuning circuits, by continuously varying the inductance of at least two coils in such a manner that the inductance of one coil is reduced the same amount as the inductance of the other coil is increased.

For a better understanding of the invention reference may be had to the following description and to the instances illustrated therein. The detuning of the individual tuning circuits be uniformly effected. 'If, for instance, the band width is to be varied in a three tube set, two

tuning circuits are displaced in the tuning with capacitance or of the inductance of the oscillatory circuits in the following manner will be necessary as regards the wave ranges:

Per cent In the case of 150 k. c 4 In the case of 250 k. c 2.4 In the case of 600 k. c 1 In the case of 1330 k. c 0.46

Since an influence of the capacitance of these oscillatory circuits is difficult owing to the great differences of the detuning necessary between the standard and long wave range as will be apparent from the above table and the above considerations, the inductance of these circuits should be influenced according to the invention,

high-frequency compressed iron powder core coils being employed for this instance in which besides the continuous variation of the inductance,

creased.

In the drawing accompanying the specification, Fig. 1 illustrates in a general manner an application of the invention to a pair of resonant circuits; Fig. 2 illustrates one embodiment of the invention adapted for uni-control purposes; Figs. 3 and 4 illustrate methods of coupling the cores in alignment with each other; Fig. 5 illustrates the invention applied to circuits between a which amplifying or other electrical apparatus is towards both sides of the relative zero line is to circuit is tuned is desired, a variation of the connected; Fig. 6 illustrates diagrammatically the application of the invention to tuning means In Figs. 1-3 this inventive idea is shown in principle. Fig. 1 shows schematically a simple band filter arrangement in the form of two coils which may be inductively, capacitively or galvanically coupled witheach other. In the case of oscillating coils not coupled with one another an arrangement as shown in Fig. 2 might be employed. In this embodiment, H-shaped or thread spool-shaped compressed iron powder cores of By the A the standard wave range.

the known type are employed which permit the balance to be effected in two ways. The coil bodies which consist of compressed iron powder core material are bored and are provided with a shiftable pin S. In the casing G there is also a device which permits a further balance and which consists of metal or mass plates M capable of being screwed which when being approached to the coil vary the inductance. Similar devices may, of course, also be employed in air core coils in the form ofintroduced mass pins, cylinder rings and the like.

The pin balance of the embodiment is so designed that when one pin is being moved from the corresponding core, the pin of the other core is moved into the latter by the same amount and that the pin of the one core is adjusted to its maximum value if the pin of the other core has assumed the minimum value. The pins may be connected with one another by a rod or by a guide tube of insulation material as shown in Fig. 3 and through a worm with the band width knob to be operated by hand. However, it is also possible to arrange the balanced pins as shown, for instance, in Fig. 4, in such a manner that they may be screwed within the coils in either direction.

The case already mentioned as an instance, i. e., that the circuits of the tuning device are separated by tubes, is shown in Fig. 5 with the corresponding Figs. 2 and 6 for compressed iron powder core arrangement. Fig. 2 shows the simple case of two separate oscillatory circuits for one wave range, whereas in Fig. 6 separate coils are provided forthe long wave range and In Fig. 6, L1 and In denote the long wave coils, whereas Miand M2 denote the standard wave coils. Each pair of coils consisting of a standard wave coil and a long wave coil is placed in a common casing I and II respectively. In accordance with the percentage of the. variation of the band-width within the difierent wave ranges indicated in the above table, balance pins of different diameters are employed in this .case in connection with the same core shape. The coils L1 and L2 are in the instance shown equipped with pins having a large diameter, whereas pins of smaller diameter are provided for standard wave coils. In Figs. 2, 3 and 6 is indicated a way of adjusting the band width as already mentioned by means of an operating knob through a spiral disc, denoted in these figures by Sp. The balance pin is so adjusted that its balancing movement takes place as far as possible along the straight portion of the balance curve (of. Fig. 7)

The variation of the band width according to the invention is preferably employed in radio sets, since in this case, as above mentioned, the absolute amount of the band width is varied when tuning the oscillatory circuits. In order to remove this drawback, the correction according to the invention is, therefore, made, i. e., theband width is varied in accordance with the tuning operative relationship'with its associated coil,

single means operable between two extreme positions for moving said cores in unison with respect to said coils along said common' axis to thereby vary the inductance of all of said coils simultaneously, said coils and cores being arranged so that in one extreme position of said single means one of the cores is substantially completely within its coil while the other thereof is substantially wholly outside its coil, whereas, in the other extreme position of said single means the last named core is substantially wholly within its coil while the other core is substantially wholly outside its coil, and so that in any intermediate position of said single means, at least a portion of each core is within its associated coil.

- 2. In signalling apparatus adapted for operation over widely separated wave bands, individual sets of variable tuning instrumentalities .one for each of said wave bands, one of said sets including a plurality of coils each coil having an individual core, another of said sets being provided'with a plurality of coils each coil having an individual core, all of said cores being of substantally the same length, at least one of the coils and its associated core of one of said sets and at least one of the coils and its associated core of another of said sets being proportioned relative to one another so that the ratio of the effective diameter of said first coil to the effective diameter of its associated core is appreciably greater than the ratio of the diameter ofsaid other coil to the effective diameter of its associated core and single means for adjusting all of said cores in unison with'respect to their associated coils.

3. In signalling apparatus, a first pair of coils each provided with an adjustable core of ferromagnetic material for detuning the coils to opposite sides of a mid-frequency, a second pair of coils each provided with an adjustable core of ferro-magnetic material for detuning the latter coils to opposite sides of a second mid-frequency, all of said coils being mounted end to end fashion and in coaxial relation, and single means for adjusting all of said cores in unison with respect I WILHELM MENNERICH. OTTO SIEPKE. ALEXANDER SCI-IAAF.

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