US1988444A - Multifrequency tuning system - Google Patents

Description

Jan. 22, 1935.

W. l. CARPENTER MULTIFREQUENCY TUNING SYSTEM Filed July 28, 1932 4 Sheets-Sheet l 52m. 22, 1935. w. CARPENTER l,958,444

MULTIFREQUENCY TUNING SYSTEM Filed July 28, 1932 4 Sheets-Sheet 2 Wbstzrlflar enkr Jan. 22, 1935. w. I. CARPENTER 1,983,444

MULTIFREQUENCY TUNING SYSTEM Filed July 28, 1932 4 Sheets-$heet 3 Jan. 22, 1935.

Filed July 28, 1932 4 Sheets-Sheet 4 arrow,

Patented Jan. 22, 1935 UNITED STATES PATENT OFFICE 9 Claims.

This invention relates to a multi-frequency tuning system more particularly to a multi-unit all-wave variable condenser and an automatically operable switching means, with the condenser 5 having an exceedingly wide range of capacity,

sufficient to cover the short wave band in addition to the regular radio broadcast band and with said means for controlling the oscillating circuits of radio receivers,

The invention further aims to provide a multifrequency tuning system for covering various frequency ranges and for the simultaneous control of a multiplicity of similar tuned circuits by a minimum of switching devices requiring but one switching to make operative any number of tuned circuits covering the same frequency range, but utilizing separate switchings for controlling any number of circuits tuning different frequency ranges. The necessary switching is carried out through thev use of a multi-unit variable condenser of the rotary type including sets of rotors arranged in staggered relation around a common shaft. The rotors of the set tuning the same portion of the spectrum bear the same angular relation to each other, each set of rotors for a higher or lower frequency range being arranged in a progressively staggered relation, but all rotors covering the same range bear the same anular relation to each other. The sets of rotors are so arranged about the shaft that when the latter is rotated through 360, the rotors progress through their respective stators in a direction to produce a constantly increasing or decreasing frequency range. The switching devices are so disposed relative to the sets of rotors and to the shaft that a leading switching device perates in conjunction with its associated circuits and opens at the moment that the set of rotors of its associated condenser assembly have completed their course through the stators of such assembly and with each follower switching device closing the next successive condenser assembly through to its associated circuits as the rotors of such successive assembly enter their respective stators.

A further object of the invention is to provide, in a manner as hereinafter set forth, a mu1ti-frequency tuning system including a multi-unit allwave condenser having staggered rotor units, with each unit having automatic circuit control, making it possible to have one condenser unit and coil very highly peaked to a part of the wave band, and with the next condenser unit taking up where the previous one left off, and likewise being highly peaked over the next assignment of wave band thereby providing a condenser that is peaked all the way from its minimum wave length to its highest wave length thereby providing for a very strong signal strength and increasing the efli- 5 ciency of a receiving set.

A further object of this invention is to provide, in a manner as hereinafter set forth, a system of the class referred to including a. variable condenser of simple, practical construction, having 8. capacity range sufficient to cover the entire short wave band, in addition to the regular radio broadcast band, and yet, not to crowd the stations on the dial. This ability is accomplished by the novel arrangement of the parts, and determination of capacities of the units of the condenser to peak with each coil, individually, and respectively connected to that particular unit of the condenser. The rotary of condenser is constituted of, at least three or more sets or groups of condenser units each including a rotor of a capacity that proves best to match up with the inductance of the coil that it is electrically connected with, for tuning that particular assigned wave band. The three or more unit rotors are arranged around the condenser shaft, circumferentially, in a spaced, staggered, symmetrical, concentric relation.

The condenser is designed to complete a full turn of 360 degrees, over and over again. Starting at zero on the dial, on up to 360 degrees, and then with a slight turn of the dial, zero returns. It is thereby shown that as the full capacity of the condenser is reached and passed, it automatically drops back to the minimum capacity again. To rotate the dial in reverse order, the above facts are true in reverse order.

With the multi-unit all-wave condenser, in accordance with this invention, each unit of the condenser is peaked for highest efliciency with the one and only coil that this unit has to tune, thereby, covering that particular section of the wave band with the very highest efliciency. This fact is carried out, and is true, with each of the unit condensers, thereby, making the multi-unit all-wave variable condenser, a highly efiicient condenser throughout all Wave lengths, and at the same time covers a very wide Wave band.

The short wave band may be divided into three, four or more sections, as desired, with a unit of the condenser to tune each section.

The apparatus includes an automatic switching means for cutting in and out each individual condenser unit covering the different wave bands. This feature is accomplished by a number of switching blocks arranged on the hub of one ro- 30, 31, s2. 33.34 and 35.

tor of each group. As the rotor of a unit is turned the switching block makes contact with a spring lever contact that forms a part of the electrical circuit of that unit thereby completing the circuit to this unit just at the moment that the rotor is beginning to enmesh into the stator of the unit. At this moment, also the unit of the condenser preceding the aforesaid unit of the condenser, is thrown out of circuit automatically. This process goes on consecutively with each unit of the condenser being thrownin'and out of circuit during the turning of the tuning dial.

The present method in daily use is to manually change the coils, or else, manually operate a switch that cuts out one set of coilsand cuts in another set of coils. In each case the tuning dial had to be turned through its full range, to completely cover each set of coils, as changed. This necessitated a great amount of turning and tuning" the dials, and loss of time, etc.

3 There are" no stray magnetic fields sct up, by the-various coils, since only one is actually in circuit at a time. It is preferable to use an individual coilfor each band. Whereas, when a tapped coil is used there is some magnetic reactance created in the adjoining windings, even thoughnot directly connected in circuit at the time; This fact pertaining to. type of coil used, however, has no bearing on the condenser. That is for the engineer to choose as he desires.

' To the above ends essentially, and to others whichmay hereinafter appear, the invention consists of such parts and such combination of parts which fall within the scope of the invention as claimed.

r In the drawings:

Figure 1 is an elevation, partly in section illustrating the multi-unit all-wave variable condenser and the switches for the condenser units used in connection with the wave bands.

Figure 2 is a sectional detail illustrating one of the switches for one of the short wave condenser units in'open position.

Figure-3 is a view similar to Figure 2 with the switch closed. 7 Figures 4 and 5 are diagrammatical views illustrating respectively the apparatus in inoperative and operative position.

" Figure 6 is a diagrammatical view illustrating a modified form of switch for a rotor unit and a modified circuit arrangement for the rotary unit and its associated unit, the circuit being opened.

Figure 7 is a View similar to Figure 6 of the modification illustrated by the latter and with the circuit closed.

Referring to Figures 1, 2 and 3 a casing is designated 1 and is adapted to enclose the multiunit all-wave variable condenser generally indicated at 2. The condenser is formed of groups or sets of units. Each unit is formed of a rotor assembly and astator assembly to be hereinafter referred to. The bottom 3 and front and rear walls 4, 5 respectively of casing i are illustrated. The walls 4, 5 are formed with aligning openings 6, '7 respectively and with bosses 3, 9 respectively which register with openings 6, 7 respectively. The bottom 3 is formed with a series of spaced aligning openings 10, 11, 12, 13, l4, l5, 16, 17 and 18. The walls of said openings are threaded.

Secured within the casing l is a series of ver-' tically disposed spaced partitions or shields 19, 20, 21, 22, 23, 24, 25 and 26, which in connection with the casing provide compartments 27, 23, 29, The partitions are formed with spaced aligning openings 36 which align with openings 6 and 7. Mounted at its inner end in the opening 6 and boss 8 and extending through the aligning openings 36, boss 8 and opening 6, as well as projecting outwardly from wall 4 is a rotatable shaft 37 forming an element of the condenser 2. The shaft 37 also extends outwardly through a dial 33 attached to the front of wall 4 and has secured thereto a turning knob or finger piece 39whichopposes the outer face of dial 38.

Arranged in compartments 27, 28, 29, 30, 31, 32, 33, .34 and 35 respectively are stator assemblies 40, 41, 42, 43, 44, 45, 46, 47 and 48 forming elements of the condenser 2 and each consists of a gang of vertically disposed parallel spaced plates 49 of substantially triangular contour standing on their widest end and each having a segmental top edge 50. Each gang of plates at its lower end is mounted in a channel-shaped member Spacers 52 are arranged between the-plates of each gang at the bottom of the unit. The openings 16 to 18 inclusive communicate respectively with compartments 2'7 to 35 inclusive and threadedly engaging with the Wall of each is a vertically adjustable threaded member 53 carrying at. its upper end a flat plate 54 opposing the bottom of a member 51 and having a head 55 at its lower end. Each member 53 carries a clamping nut 56.

A member 51, a threaded member 53 and the plate 54 carried by the latter provide a balancing condenser. The purpose of each balancing condenser is to be able to perfectly balance out, or peak the stator assembly to the coil with which it has to tune. In other words, the inductance of the coil is made to match veryclosely the capacity'of the stator assembly that is to tune this particular coil, and the slight difierence in match is compensated for by the adjustment of the balancing condenser on the stator assembly 3 to slightly change the capacity 0:? the stator assembly to perfectly match the coil. The channelshaped member 51 of each balancing conductor is in electrical connection with the plates of that stator assembly with which it is associated.

Each stator assembly is supported in insulated relation over bottom 3 by two pairs of upstanding insulated angle-shaped-brackets and a coupling screw connecting the units of the brackets of each pair together. The screws extend through the lower corners of the plates of the gangs, .through the spacers and members 51. The brackets of one pair. are designated 57, those of the other pair at 58 and the coupling screws at 59, 60. The brackets of each pair are secured to bottom 3, by holdfast devices 61. Each bracket includes a vertical and a horizontal arm, the latter extending outwardly at right angles to the lower end of the former. The length of the vertical arm is greater than that of the horizontal arm. The brackets are spaced from and insulated from the walls 4, 5 and the partitions.

The wall 4 and partitions l9, 20, 21 and 22 provide'respectively the outer wall of the compartments 2'7, 28, 29, 30 and 31. Secured to the rear faces of the wall and partitions 19, 20, 21 and 22 are respectively automatically operable switching units 62, 63, 64, 65 and 66 arranged over and in proximity to shaft 37. Each switching unit includes an oblong fiatwise disposed rigid bar 67 extending transversely with respect to a partition or wall 4 and provided with a vertically disposed extension 68 at an end terminal part of one of its lengthwise edges. The extension 6.6 is apertured for the passage of holdfast devices 69 to fixedly secure bar 67 to the partition or wall 4. The extension 68 is arranged over shaft 37 and bar 67 extends outwardly withrespect to the latter. Extending through and threadedly engaging with bar 67 is a vertically disposed regulating and stop screw 69' arranged outwardly from extension 68. Each switch unit includes three terminals 70, 71 and'72 having electrically connected therewith and extended rearwardly therefrom superposed, normally spaced, resilient circuit closures 73, 74 and 75 respectively which are mounted in and extend rearwardly from a block 75' of insulation which depends from the outerv end of bar 67. The outer ends of said closers are attached to said terminals. The closers 73, 74 have coacting contacts 76, 77 respectively. The closer 74 carries an insulated block 78 for insulating it from closer 75 when the switch unit is operated. The screw 69 is arranged over closer 73. The closers 73, 74 and 75 are simultaneously shifted from normal spaced position and the manner in which this is done will be presently referred to.

With reference to Figures 4 and 5 it will be noted that from terminal 70 a circuit connection 79 extends to an induction coil 80 and from the latter extends a circuit connection 81 to a stator assembly associated with the regular radio broadcast band oscillator circuit. It will also be noted that a circuit connection 82 extends from terminal 72 to an induction coil 83 and from the latter extends a circuit connection 84 to a stator assembly associated with the regular radio broadcast band, antenna or radio frequency circuit.

The circuit closer 75 of each switching unit extends over the shaft 37 and is arranged in the path of a lug cam or block disposed radially with respect to shaft 37, the lug acting to engage the inner portion of closer 75 to close the circuit of a stator assembly associated with that particular wave band. The lug further acts to shift the inner portion of closer 75 upwardly to engage block 78 which in turn will shift the inner portion of closer 74 upwardly to bring contacts 76 and 77 into engagement to close the circuit of a stator assembly of antenna or radio frequency circuit of same wave band.

Arranged in the compartments 27, 28, 29, 30 and 31 are rotor assemblies 85, 86, 87, 88 and 89 forming elements of the units of the condenser 2 and associating respectively with the stator'as semblies 40, 41, 42, 43 and 44. The rotor units 85, 86, 87, 88 and 89 are secured to sleeves 90, 91, 92, 93 and 94 respectively. The sleeves are rigidly fixed to shaft 37 whereby such rotary assemblies will bodily move with the shaft. Each rotary assembly consists of a gang of spaced, parallel plates. Each plate has a straight and a curved edge 96, respectively. Each plate is anchored in a sleeve at the point of joinder of the inner ends of said edges. The plates of assemblies 86, 87 and 88 are substantially semioval in contour. The plates of assemblies 85 and 89 are of like contour and area and of a contour more than the half of an oval. The assemblies 85 and 89 are arranged in alignment. The assemblies 85, 86,87 and 88 are arranged around shaft 37 in a spaced, staggered, symmetrical, concentric relation with respect to each other. The assemblies 86, 87, 88 and 89 are arranged around shaft 37 in a spaced, staggered, symmetrical, concentric relation with respect to each other.

Each stator assembly will be hereinafter referred to as a stator. Each rotor assembly will be hereinafter referred to as a rotor.

The rotors 85, 86, 87, 88 and 89 are arranged relatively to each other, to shaft 87 and to stators 40, 41, 42, 43 and 44 to provide for a follower rotor to enter its associate stator simultaneously with the leaving of a leading rotor from the as sociated stator for the latter.

The rotors 85 to 89 inclusive are provided to split the wave band into groups of meters, and rotors B5 and 89, each is, by way of example for from two hundred to five hundred and fifty meters; rotor 86 for from sixty-five to two hundred meters; rotor 87 for from twenty-two to sixty-five meters and rotor 88 for from fifteen to twenty-two meters.

The sleeves 90, 91, 92, 93 and 94 at the outer ends thereof are provided with lugs 103, 104, 105, 106 and 107 respectively for automatically operating the switching units 62, 63, 64, 65 and 66 respectively. The lugs abut the periphery of and are disposed lengthwise of shaft 37. The lugs 103 and 107 are arranged in longitudinal alignment; the lug 104 is arranged out of alignment with respect to lugs 103, 107; the lug 105 is arranged out of alignment with respect to lugs 103, 104, 107 and the lug 106 is arranged out of alignment with respect to lugs 103, 104, 105, 107. The switching units 62 and 66 are simultaneously operated by lugs 103 and 107. The switching units 63, 64 and 65 are not operated simultaneously. The switching units 63, 64 and 65 are not operated simultaneously with either unit 62 or 66. After a lug clears a circuit closer 75 the switching unit automatically returns to the position shown in Figures 2 and 4.

Carried by and bodily moving with shaft 37 are spaced sleeves 108, 109, 110 and 111 carrying rotor assemblies 112, 113, 114 and 115 respectively forming elements of the units of the con denser 2 hereinafter termed rotors and which associate with the stators 45, 46, 47 and 48 respectively. The rotors 112, 113, 114 and 115 out in and out of circuit by switching devices 62, 63, 64, 65 and each thereof includes a gang of spaced parallel plates. The plates 116 of unit 112 correspond in contour to that of the plates of rotors 85 and 89. The plates 117 of rotor 113 correspond in contour to that of the plates of rotor 86. The plates 118 of rotor 114 correspond in contour to that of the plates of rotor 87, and the plates 119 of unit 115 correspond in contour to that of the plates of rotor 88. Preferably the number of plates of rotors 112, 113, 114 and 115 will correspond respectively to the number of plates of rotors 85, 86, 87 and 88 and the number of plates of rotor 112 preferably will correspond to the number of plates of rotors '85 and 89. The rotors 112, 113, 114 and 115 are arranged relatively to each other, to shaft 37 and to stators 45, 46, 47 and 48 in the same manner as the rotors 85, 86, 87, and 88 are arranged relatively to each other, to shaft 37 and to stators 40, 41, 42 and 43. Separate switching units are not employed in connection with rotors 112, 113, 114 and 115 as are employed in connection with rotors 85, 86, 87 and 88, since the rotors 112, 113, 114 and 115 are respectively controlled by switches 62, 63, 64, 65; switch 66 operates only the circuit associated with the condenser unit provided by stator 44 and rotor 89 by virtue of this unit acting only in the broadcast band to acquire selectivity not possible with two tuned circuits, but such selectivity being unnecessary in the shorter wave bands.

With reference to Figures 4 and 5 there is shown a circuit connection 116 leading from terminal '71to a rotary unit associated with a stator unit employed in connection with the'regular broadcast band. The sleeves 108, 109, 110 and 111 are not provided with lugs. The units 112, 113, 114 and 115 are elements of condenser 2.

The shaft 3'7 is common to the rotary units 85, 86, 87, 88, 89, 112, 113, 114 and 115.

The rotary units employed in connection with the short wave band do not trail in the same path on rotation. The rotary units employed in connection with the regular broadcast band do not trail in the same path on rotation.

The arrangement as described provides for a series of multiple units using a single stator to accommodate the multiple units in staggered relation on the rotor covering thev whole wave band making use of a single revolution of the rotor.

The rotary and stator units, each being formed of a gang of plates, the number of theplates of each unit being different whereby each multiple condenser unit is of a different capacity.

The switching units throw out one set of coils from connection to the stator of condenser and throw in the next set of coils next above or below in wave length according to which way the rotor is turned.

With reference to Figures 6 and 7, each switch unit as shown will include but one terminal 117 from which leads a circuit connection 118 to an induction coil 1'19 and from the latter leads a circuit connection 119 to a stator unit 120 associated with arotary unit 121. Leading from terminal 117 to an induction coil 122 is a circuit connection 122' and leading from induction coil 122 to a stator unit 123 is a circuit connection 124. The stator unit 123 is associated with a rotary unit 125. The units 121 and 125 are upon a com mon metallic shaft 126 which corresponds to shaft 3'7. The switch unit as shown in Figures 6 and 7 includes a single resilient circuit closer 127 which extends from terminal 117 and is provided with a contact point 128 adapted to be engaged by a lug 129 carried by shaft 126. The circuit including the induction coils 119, 122 will be closed when lug 129 comes into engagement with contact point 128 when shaft 126 is rotated. By the foregoing arrangement, a rotary unit and its associated unit are cut in or out instantly with the breaking of the ground.- 7

With reference to Figures 4 and 5, ground connections are indicated at 132, 133 and 134. With reference to Figures 6 and '7, ground connections are indicated at 135, 137 and 138.

What I claim is:-

1. In a multi-frequency tuning system for covering various frequency ranges and for simultaneously controlling a multiplicity of similar tuned circuits, a condenser including ganged rotors, ganged stators, each associated with a rotor, a rotatable shaft common to the rotors, said rotors being arranged in staggered relation about said shaft, said rotors being arranged in sets of two or more, one set tuning the same portion of the spectrum and a portion different from that tuned by any of the other sets, the rotors tuning the same portion of the spectrum bearing the same angular relation to each other and the rotors of each higher or lower frequency range tuning set being arranged in a progressively staggered relation, said sets of rotors being so arranged about said shaft that when the shaft is rotated 360 each set of rotors progress through their respective stators in a direction which produces a constantly increasing or decreasing frequency range, switches arranged in co-relation with respect to said shaft, each associated with a set of rotors and arranged so that each operates in conjunction with its associated circuits, each switch opening at the moment the rotors of that condenser assembly with which it is associated have completed their course through their associated stators and closing the set of rotors of the assembly through to their associated circuits at the moment at which the rotors of the assembly begin to enter their associated stators. I

2. In a multi-frequency tuning system for covering various frequency ranges and for simultaneously controlling a multiplicity of similar tuned circuits, a condenser including a series of sets of spaced condenser units, each set consisting of more than one condenser unit, each unit of each set formed of a stator and a rotor for passage through the stator, one of the rotors of each set constituting a control for the circuits of the units of the set, said sets progressively increasing in capacity, a rotary shaft common to the rotors of the said sets and electrically connecting the rotors of each set together, the rotors of said sets being fixed to said shaft for bodily and simultaneously moving therewith, means on the control rotors of each set of units for simultaneously closing the circuits of a set of units on the rotation of said shaft, the said means on said control rotors being arranged in staggered relation to provide for the simultaneous closing of the circuits of the units of one set independently of the closing of the circuits of the units of said other sets.

In a multi-frequency tuning system for covering various frequency ranges and for simultaneously controlling a multiplicity of similar tuned circuits, a condenser including a'series of sets of spaced condenser units, each set consisting of more than one condenser unit, each unit of each set formed of a stator and a rotor for passage through the stator, one of the rotors of each set constituting a control for the circuits of the units of the set, said sets progressively increasing in capacity, a rotary shaft common to the rotors of the said sets and electrically connecting the rotors of each set together, the rotors of said sets being fixed to said shaft for bodily and simultaneously moving therewith, means on the control rotors of each set of units for simultaneously closing the circuits of a set of units on the rotation of said shaft, the said means on said control roi-ors being arranged in staggered relation to provide for the simultaneous closing of the circuits of the units of one set independently of the closing of the circuits of the units of said other sets, the stators of the units of each set of units being insulated from each other, and the stators of the units of one set of units being insulated from the stators of the other sets of units, the stators of the units of the said sets being arranged in parallel spaced relation and disposed in a row parallel to said shaft.

4. In a multi-frequency tuning system for covering various frequency ranges and for simultaneously controlling a multiplicity of similar tuned circuits, a condenser including a series of sets of spaced condenser units, each set consisting of more than one condenser unit, each unit of each set formed of a stator and a rotor for passage through the stator, a hub for each inner end of each rotor of each unit of the said sets of units, said sets progressively increasing in capacity, a rotary shaft common to and having said hubs fixed thereto for bodily moving in unison with the rotors of the said sets of units, said shaft in connecticn with said hubs electrically connecting the rotors of each set of units together, and means carried by a hub of one of the rotors of the units of each set acting, when the shaft is rotated, for simultaneously closing the circuits of the units of one set of units independently of the closing of the circuits of the units of the other of said sets of units.

5. In a niulti-frequency tuning system for covering various frequency ranges and for simultaneously controlling a multiplicity of similar tuned circuits, a condenser including a plurality of sets of condenser units, each unit of a set formed of a stator and a rotor for passage through the stator, the rotors of each set tuning the same portion of a spectrum, that portion of the spectrum tuned by the rotors of one set being different from that portion tuned by the rotors of any of the other of said sets, a rotary shaft common to the rotors of each of said sets, the rotors of each set bearing the same angular relation to each other and the rotors of each higher or lower frequency range tuning set being arranged in staggered relation about said shaft, and a separate controlling means for each set arranged in co-relation with respect to said shaft to provide for the simultaneous closing and the simultaneous opening of the circuits of all of the units of one set independently of the closing and opening of the circuits of the said other sets of units respectively at the beginning and at the end of the passage of the rotors of one set of units through the stators of such set.

6. In a multi-frequency tuning system for covering various frequency ranges and for simultaneously controlling a multiplicity of similar tuned circuits, a condenser including a plurality of sets of condenser units, each unit of a set formed of a stator and a rotor for passage through the stator, the rotors of each set tuning the same portion of a spectrum, that portion of the spectrum tuned by the rotors of one set being different from that portion tuned by the rotors of any of the other of said sets, a rotary shaft common to the rotors of each of said sets, the rotors of each set bearing the same angular relation to each other and the rotors of each higher or lower frequency range tuning set being arranged in staggered relation about said shaft, and a separate controlling means for each set arranged in co-relation with respect to said shaft to provide for the simultaneous closing and the simultaneous opening of the circuits of all of the units of one set independently of the closing and opening of the circuits of the said other sets of units respectively at the beginning and at the end of the passage of the rotors of one set of units through the stators of such set, each of the said means having a part thereof carried by a rotary part of one of the unit of a set and a part located adjacent to the shaft and in the path of the part carried by said rotary part.

'7. In a multi-frequency tuning system for covering various frequency ranges and for simultaneously controlling a multiplicity of similar tuned circuits, a condenser including a plurality of sets of condenser units, each unit of a set formed of a stator and a rotor for passage through the stator, the rotors of each set tuning the same portion of a spectrum, that portion of the spectrum tuned by the rotors of one set being difierent from that portion tuned by the rotors of any of the other of said sets, a rotary shaft common to the rotors of each of said sets, the rotors of each set bearing the same angular relation to each other and the rotors of each higher or lower frequency range tuning set being arranged in staggered relation about said shaft, and a separate controlling means for each set arranged in co-relation with respect to said shaft to provide for the simultaneous closing and the simultaneous opening of the circuits of all of the units of one set independently of the closing and opening of the circuits of the said other sets of units respectively at the beginning and at the end of the passage of the rotors of one set of units through the stators of such set, each of the said means having a part thereof carried by a rotary part of one of the units of a set and a part located adjacent to the shaft and in the path of the part carried by said rotary part, the said parts carried by the rotary parts of said units being arranged in staggered relation with respect to each other.

8. In a multi-frequency tuning system for covering various frequency ranges and for simultaneously controlling a multiplicity of similar tuned circuits, a condenser including a series of groups of condenser units, each unit of a group consisting of a stator and a rotor for passage through the stator, one of the rotors of each group of units constituting a control for the group, said groups of condensers progressively increasing or decreasing in capacity, the rotors of each group of units being approximately parallel, a rotary shaft common to the rotors of said pairs of units and electrically connecting the rotors of the groups together, the inner ends of the rotors of said units being fixedly secured to said shaft to provide for the bodily moving of the ,rotors therewith, the rotors of one group being disposed in staggered relation about said shaft with respect to the rotors of the other groups, means on one end of the control rotor of each group for operating a device to make the units of the groups active, the said means on one end of said control rotors being arranged in staggered relation about said shaft to provide for the activity of one group of units independently of the other groups of units, the stators of each group of units being insulated from each other, the stators of one group of units being insulated from the stators of the other groups of units, the groups of stators being arranged in parallel spaced relation, and the stators of said groups of units being disposed in a row parallel to said shaft.

9. In a multi-frequency tuning system for covering various frequency ranges and for simultaneously controlling a multiplicity of similar turned circuits, a condenser including ganged rotors, ganged stators, each associated with a rotor, a rotatable shaft common to the rotors, said rotors being arranged in staggered relation about said shaft, said rotors being arranged in sets of two or more, one set tuning the same portion of the spectrum and a portion different from that tuned by any of the other sets, the rotors tuning the same portion of the spectrum bearing the same angular relation to each other and the rotors of each higher or lower frequency range tuning set being arranged in a progressively staggered relation, said sets of rotors being so arranged about said shaft that when the shaft is rotated 360 each set of rotors progress through their respective stators in a direction which produces a constantly increasing or decreasing frequency range, switches arranged in co-relation with respect to said shaft, each switch being associated with a set of rotors and arranged so that each operates in conjunction with its associated leave their associated stators and at the moment at which the rotors of the condenser assembly with which it is associated begin to enter their associated stators.

WEBSTER I. CARPENTER.

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