US1917077A - Radio tuning device - Google Patents

Description

July 4, 1933. W D I 1,917,077

RADIO TUNING DEVICE Filed April 30, 1930 4 Sheets-Sheet l 02%!275/9 ea/ye 71 042 W W G. WALD RADIO TUNING DEVICE July 4, 1933.

Filed April 30, 1930 4 Sheets-Sheet 2 yea/ye 71 4/51 July 4, 1933. G. WALD 1,917,077

RADIO TUNING DEVICE Filed April 30, 1930 4 Sheets-Sheet 3 Gear e Wa/a:

July 4, 1933. s. WALD RADIO TUNING DEVICE Filed April 30, 1930 4 Sheets-Sheet 4 ur- M).

Patented July 4, 1933 GEORGE WALD, or 'BELLEVILLE, ILLINOIS RADIO TUNHVG DEVICE Application filed April 30,

This invention relates to improvements in radio tuning devices, and consists in the novel construction hereinafter disclosed.

An object of the invention is to provide, in a tuning system for radio receiving circuits, a tuning device comprising a helical condenser including a plurality of units whereby separate stages of radio frequency, or separate stages of radio frequency and an oscillator circuit, may be simultaneously tuned for the reception of wave lengths of wide variation.

A furtherpbject of the invention is to provide a novel construction of a helical condenser unit that is compact in construction and which may be economically manufactured for quantity production.

Another object of this invention is to provide a novel radio receivingv set capable of accurate tuning and with which reception is possible throughout a wave band of 10 to 600 meters.

Additional objects of theinvention will be readily apparent to those skilled in the art from the following detailed description thereof, taken in connection with the accompanying drawings, in which ig. 1 is a side elevation of the condense unit shown in association with the controlling means therefor.

Fig. 2 is a diagrammatic View of one form of radio receiving circuit with which the condenser, constituting the tuning unit, is associated.

Fig. 3 is a diagrammatic view of the transformer in an oscillator or radio frequency circuit.

Fig. 4 is a detail view of an alternate form of actuator and dial drum for the condenser unit.

Fig. 5 is a detail view illustrating a feature of construction of the stator of the condenser. Fig. 6 is a further detail view of the same construction.

Fig. 7 is an isometric View showing the manner in which the plates of the stator of the condenser are assembled.

Figs. 8 to 13, inclusive, show the progressive forms of plates forming the helix of the condenser stator.

The condenser which comprises the tuning unit for the receiving circuit, as shown in the drawings, includes a frame having a base 1 adapted to support'the unit in the case of a radio receiving set. Integrally formed 1930. Serial no. 448,462.

with the base 1 are standards 2, 3 and 4. The standards 2 and 3 constitute the end members of the condenser frame, and the standard 4 constitutes a journal support for the rotor of the condenser. The condenser cage supporting the stator plates comprises circular end plates 5 and 6 of electrically non-conductive material and bars or strips 7 extending longitudinally between the members 5 and 6 and secured, respectively, to the peripheries thereof. The strips 7 are spaced equally circircumferentially at 60 apart. The condenser cage is secured in the condenser frame by a pair of screws 8 that extend through the standard 3 into the end member 5 and a pair of screws 9 that extend through the standard said shaft being supported in the plate 6 in which it is rotatively mechanically secured and the other end extending for some distance into the condenser cage. This shaft 13 is non-rotated, ho wever,exce t for the slight adjustment hereinafter escribed. This shaft has a spiral slot 14 cut in its face.

A revoluble shaft 15 extends into the opposite end of the'condenser cage and has an v2 and through a spacing block 10 and into the extension that is journaled for rotation in the standards 3- and 4. The inner end of the shaft 15 carries a sleeve 16 which is cou pled with the shaft 15 by a pin-and-slot con-' nection 17. The sleeve 16 constitutes the hub of the rotor helices of the condenser and for the dial drum.

The sleeve 16 has a pin 18 on its inner face and near its open end, said pin 18 being adapted toride in the spiral slot 14. Thus, as the shaft 15 is rotated in one direc tion, the sleeve 16 by reason of the pin-andslot connection 17 will rotate with the shaft and will travel inwardly by reason of the pin 18 riding in the slot 14. When the shaft 15 is rotated in the opposite direction the sleeve 16 will move outwardly from the shaft 13. The rotor elements of the condenser are carried by the sleeve 16. and by the operation of the shaft 15 will be moved into and out of condensive relationship with the stator elements to a greater or lesser degree, as will be more fully hereinafter explained.

Any suitable means may be provided for rotating the shaft 15. In the embodiment shown in Fig. 1 of the drawings the actuator for the shaft 15 comprises a pulley 19 supported on a shaft 20 which shaft may be revolved by a knob (not shown) accessible from the outside of the .radio receiving set case The pulley 19 is operatively connected with a pulley 21, pinned 'to the shaft 15, by a flexible connection 22. The faces of the pulleys 19 and 21 may be arranged at any suitable angle so as to position the operating knob at a convenient place in the panel of the radio receiving set case. The shaft 15 is held in proper longitudinal adjustment by collars 23 and 24 pinned to said shaft 15 and abutting respectively against the faces of the shaft journals in the standards 3 and 4.

In Fig. 4 of the drawings a modification of the arrangement for operating the condenser shaft is shown, and in this figure is also shown an alternate arrangement of an indicating drum- In this embodiment a pulley, corresponding to the pulley 19 and therefore similarily numbered, is operatively connected with a pulley on the shaft 15 corresponding to the pulley 21 and therefore similarly numbered and with a separate pulley 25 which operates a shaft 26 on which the dial drum is carried. The connection for operating the pulleys 21 and 25 comprises a flexible connection corresponding to the connection 22 and therefore similarly numbered. The differences between this construction and the construction shown in Fig. 1 is that the ratio between the pulleys 21 and 25 is such that the degree of rotation of the pulley 25 is half that of the pulley 21. Therefore, the dial travels half the rate of the travel of the condenser rotor; whereas in Fig. 1 the dial is carriedby the sleeve 16, and therefore makes the same number of turns as the rotor and advances with it.

The shaft upon which the pulley 19 of Fig. 4 is mounted corresponds to the shaft 20 of Fig. 1 and therefore is similarly numbered. In Fig. 4 this shaft is shown as operated by a knob 27 on the outside of the panel of the radio receiving set case.

In Fig. 1 the dial is in the form of a cylinder on the periphery of which there is a spiral scale, said dial being mounted upon the end of the sleeve 16 and turning there with. In Fig. 4 a similar scale (not shown) is mounted on a drum that is carried by the shaft 26. The dial in both instances constitutes means for guiding the adjustment of the rotor of the condenser.

The stator'portion of the condenser that is supported in the condenser cage 15 constructed in a novel manner and includes gen-- erally three consecutive series of plates, the

forms of which are shown specifically in Figs. 8 to 13 of the drawings, so "arranged as to form three separate helices. The plates are desi ned to be formed from sections stamped by standard dies which when assembled form a helix of increasing area. -As specifically shown, each helix consists of six plates, the form of each being shown respectively in Figs. 8 to 13, inclusive. They may be punched from flat stock and then deformed to constitute a part of a continuous helix. The split ends are deflected to give a pitch of approximately three-eighths of an inch to the helix thread. Each plate is provided with lugs 29, 30 and 31 by means of which they are secured in slots formed in theinner face of the member 7.

The method of assembling the plates to form the threehlices is as follows:

A series ofthree plates, as shown in Fig. 8, are placed side by side in the condenser cage. The three plates of Fig. 8 are then placed in the condenser cage so that the lugs 29, 30, and 31, seat in slots formed in the inner face of the members 7, the lugs 29 of each of the three plates being displaced 120 from each other.- The remaining plates shown in Figs. 9 to 13, inclusive, are similarly assembled, the lugs 29, 30- and 31, being placed in the same respective slots as the corresponding lugs on other plates of the same series. The plates of each helix are matched at their ends thereby-forming three continuous helices arranged side by side and interthreaded, each helix increasing in area from its inner end toward the outer end thereof. All of the lugs 29 of each series are in contact with the respective inset con-.

ductor bars 12 in the members 7, and the corresponding lugs 30 and 31 contact with the diametrically opposite bars 12.

In assembling the plates in the condenser I cage a spacing template maybe used to prop- I erly position the lugs in the respective slots in which they are mounted and, after the plates are positioned, they may be soldered in place, or spacing washers may be used between the plates and they may be clamped in place by' a suitable construction, if de-' sired. It will thus be seen that the three stator units are secured in the condenser cage so that the beginning of each stator unit, as well as their termination, is 120 apart. Or the beginning of all the stator and rotor units may be on the same line, but the stator plates so stamped out as to have lugs 29, 30 and 81 of each unit displaced 120 on their circumferences.

Three leads 32, 33 and 34 are taken ofl the respective bars 12 for connecting the separate stator units of the condenser into theradio receiving circuit, as will be more fully ex plained hereinafter.

The rotor of the condenser is made up of three helices similarly assembled from series of similar plates, except that the plates of the rotor are uniform in area. The three the rotor plates in said grooves.

It should be noted, therefore, that in the construction of the stator and rotor units of the condenser there is provided three series of helices for the stator. which are adapted to be brought into condensive inter-relation with the three helices of the rotor. The condensive surface relationship between the rotor plates and the stator plates gradually increases as the rotor is moved into the stator by the rotation of the shaft in one direction, and decreased as the shaft is rotated in the opposite direction.

The distance between the rotor and stator plates is approximately one-sixteenth of an inch less the thickness of two plates. This distance may be slightly regulated by a con struction for adjusting the rotative position of the shaft 13. The shaft 13 extends through the end plate 6 and is provided with a knurled knob by which it may be given a slight rotation to change the relationship of the slot 14 to the thread of thestator helices. A set screw 36 extends through a slot 37in the knob 35 and into the plate 6 and provides means for setting the adjustment effected by the knob- 35, which adjustment is limited by the length of the slot 37.

The platcsshown in Figs. 12 and 13 may preferably be made of a. greater thickness than the remaining plates, and, therefore,

the dielectric space between the rotor and stator plates is reduced. This results in an effective capacity for these plates double that of the area. The result of this is that tuning can be effected by the last three turns of the condenser to a wave band of from 200 to 600 meters, while the first three turns are utilized to tune in a wave band of 10 to 150 meters.

In place of arranging the plates'of the condenser stator in interfitting relationship,

they may be arranged in consecutive longitudinal positions and the plates of the rotor may also be arranged in corresponding 1ongitudinal alignmentto cooperate with the separated stator units, in which event the pitch of the helices of both the rotor and the stator may be decreased. The modified form of actuator illustrated in Fig. 4 may be utilized with this construction so that the dial may have the scale with suitable intervals to indicate the position of the condenser elements.

In Fig. 2 of the drawings there is illustrated a radio receiving circuit into which the condenser of the construction hereinbefore described is connected. It willbe unnecessary to describe the various circuits as the undescribed portion of the diagram will be readily recognized as the standard con- 7 struction of a heterodyne circuit. The manner in which the condensers are connected into the receiving circuit, together with the control of the secondary of an oscillator clr- -cuit and of one of the radio frequency circuits before the detector, provides for tuning the receiving set to a wide variation of radio frequency. This is accomplished by controlling the induction of the secondary of the oscillator and the radio frequency circuits and by controlling the capacity of the condenser in co-ordination with the induction. A represents the oscillator circuit and B and C represent the radio frequency circuits with which we are primarily concerned.

In Fig. 3 of the drawings is shown a diagram of the particular form of transformer employed both in the oscillator and radio frequency circuits A and B.

By reference to the circuit B it will be noted that the circuit consists of an untuned vacuum tube 38, the plate of which connects through a primary 39 to 13+ 160 v. The primary has, for example, twenty to twenty-five turns and is wound on a spool or holder 40 (Fig. 3), which spool or ho der also carries a part of the secondary winding. The primary and the portion of the secondary that is wound on the spool 40 has a one to one ratio and has an induction of approximately 103 m. henries. Adjacent to the spool 40 and in the same magnetic'path is a second spool 41 upon which is wound the remainder of the secondary, for example, to turns, and has an induction of approximately 205 1n. henries;

.The windings of the secondary on the I spool 40 1s lndlcated by 42 (Fig. 2) and that portion of the secondary wound on the spool 41 is indicated by 43 (Fig. 2). It will be understood that the magnetic path between the two portions of the secondary is continuous. Therefore, the total induction when both portions of the secondary are connected is the sum of their separate induction or approxlmately 308 m. henries. The portion of the secondary 43 is cut in and out by the switch 44. The transformer therefore may be controlled to provide an induction either of 103 in. henries or 308 In. 'henries, for example.

By reference to Fig. 2 it will be noted that the switch 44 is so connected with the second radio frequency circuit C that when the sw tch is down the. second stage of radio frequency is cut out.

When the leads 32, 33 and 34 from the respective helices of the-condensrr are connected to the circuits B, C and A, respectively, as shown in Fig. 1, the capacity and inductance of the circuitsare balanced to produce resonance at predetermined frequencies in any rotation of the condenser, i. e. the inductance in each of the circuits being the same and an equal amount of capacity being added at all times to'produce resonance for the selected frequency. By operating the switch 44 the induction in the circuits A and B are reduced because of cutting out the supplemental turns of the secondaries of their transformers and the circuit C is cut out.

The following table gives the capacity in m. farads required for the necessary resonance of a circuit when employed with the transformer specifically illustrated and described adapted to produce an inductance L of either 308 or 103 m. henries, in order to tune to the various wave lengths or frequencles as indicated in the table Approximate .Wave Frequencapacity regg ga g gg' length in cies in quired when g g' 103 meters k.c. L 308 m. m hemies henries 600 500 000375 m.f. 500 600 000268 mi. 400 750 000102 m.f. 300 1, 000, 000095 mi. 200 1, 500 000045 IlLf. 150 2, 000 000024 mi. 00007 mi. 000027 m.f. 000017 mi. 000011 IILf. 000008 IILf. 000005 mi. 000003 1111. 0000014 IILf. 00000048 mi. 00000027 m.f.

In the following table is shown the areas of the plates illustrated respectively in Figs.

' 8 to 13 of the drawings, assuming an exterior diameter of 4.5 inches and approximate interior diameters as shown in the second column. In the last column is shown the capacity of the condenser when a rotor fheliX has been advanced in steps respectively so that it adjoins the several plates. The capacities for plates Nos. 12 and 13 are based upon corrected computations due to a narrower air gap ad acent those plates, as .described above:

Approx- Approximate imate average area 33: interior (one g diamside) etersq. inches inches By a comparison ofthe above tables, it will be seen that the construction of the condenser is such as to provide a graduated capacity suficient withthe two inductance values to permit the tuning of a circuit for'the full wave band for 10 to 600 meters.

From the foregoing description it will be apparentthat the invention accomplishes its object.

While a particular radio receiving circuit is shown, the application of the invention is not limited to that particular circuit, but as may be apparent, the invention is applicable to a wide range of receiving circuits employing balanced circuits. It is to be understood that otherwise the invention is not limited to the details as shown and described, but that partsof the invention may be used to advantage without the whole, and that various changes may be made in the details of construction within the scope of the appended claims Without departing from the scope of this invention.

1 claim: 0 v

1. A condenser having a pair of helical plates, and means for progressively advancing one plate into position with the other, one of said plates comprising a plurality of circular sections distorted to form an integral part of a helix, each of said sections having an end coincident with an end of an adjacent section, and one of said sections being thicker than others to reduce the air gap between it and the cooperating plate.

2. A condenser comprising a plurality of helical stator plates in intertwined relationship, a plurality of helical rotor plates in intertwined relationship carried by a common supporting element, each of said rotor plates being adapted to cooperate with a stator plate, and means for simultaneously rotating and longitudinally moving said supporting member whereby each of said rotor plates will be simultaneously moved into cooperation with a stator plate.

3. A condenser'comprising a plurality of helical stator plates in intertwined relationship, a plurality of helical rotor plates in intertwined relationship carried by a common supporting element, each of said rotor plates being adapted to cooperate with. a stator plate, means for simultaneously rotating and longitudinally moving said supporting member whereby each of said rotor plates will be simultaneously moved into cooperation with a stator plate, and an indicating drum mounted on said supporting member.

4. A condenser comprising a plurality of like helical stator plates in intertwined relationship, a plurality of helical rotor plates corresponding in pitch and relationship to said stator plates, a common mounting for said rotor plates, and means to cause rotation.

and longitudinal movement of said mount-' ing.

GEORGE WALD.

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