US3594670A - Tuning coil assembly - Google Patents

Abstract

Tuning coil units for use in television tuners are provided which have been automatically aligned to the desired channel frequency by deforming the turns of the respective tuning coils in such manner as to cause them to take a permanent set at the proper inductance value to receive a desired television channel. The coil turns are deformed inwardly into a recess in the coil form so that the coil turns are tightly stretched about the coil form and maintain their adjusted inductance value during assembly and usage in the television tuner.

Description

United Sttes Patent [72] Inventor Morton L. Weigel Bloomington, Ind. [2]] Appl. No. 365607 [22] Filed May 13, 1970 [23 Division of Ser. No. 845,630, July 7, I969,

Pat. No. 3,521,677, which is a continuatlon of application Ser. No. 660,983, Aug. 16, I967, now abandoned [45] Patented July 20, 197I [73] Assignee Sarkes Tarzian, Inc.

Bloomington, Ind.

[54] TUNING COIL ASSEMBLY 3 Claims, 19 Drawing Figs. [52] US. Cl 336/20,

336/l92, 336/208 [5 1 im. Cl no" 27 30 [50] Field of Search 336/20, 192, 198, 208 [56] References Cited UNITED STATES PATENTS 2,252,092 8/1941 Newman 336/20 2,776,413 l/l957 Knouse 336/192 3,227,981 l/l966 Krepps, Jr. et al. 336/192 Primary Examiner-Thomas J. Kozma AllorneyMason, Kolchmainen, Rathburn & Wyss ABSTRACT: Tuning coil units for use in television tuners are provided which have been automatically aligned to the desired channel frequency by deforming the turns of the respective tuning coils in such manner as to cause them to take a permanent set at the proper inductance value to receive a desired television channel. The coil turns are deformed inwardly into a recess in the coil form so that the coil turns are tightly stretched about the coil form and maintain their adjusted inductance value during assembly and usage in the television tuner.

PATENIEDJummsn 7 3594670 sum 2 0F 8 INVENTOR mRTON L WEIGEL ATENTED JULZOIQYI I SHEET 3 BF 8 INVENTOR WRTON L. NEIGEL PATENTED JUL20|971 35941670 SHEET u [If 8 INVENTOR XDRTON L WEI GEL PATENTED JUL 20 I97! SHEET 8 OF 8 INVENTOR mRTON L. WEIGEL PATENTEI] JUL 20 :91:

SHEET 8 BF 8 INVENTOR PDRTON L WEIGEL TUNING COIL ASSEMBLY This application is a division of my copending application Ser. No. 845,630 filed July 7, 1969, now Patent No. 3,521,677, which application is itself a continuation of my application Ser. No. 660,983 filed Aug. 16, 1967, now abandoned all of which applications are assigned to the same assignee.

The present invention relates to tuning coin units which have been automatically aligned to predetermined inductance values. While the invention is of general application, it is particularly suited for and will be described in connection with the alignment of tuning coil units of the type which are used in television tuners to receive different television stations.

Certain arrangements have been heretofore proposed for providing a tuning coil unit in which a plurality of tuning coils are wound about the periphery of an elongated coil form of insulating material, the ends of the coils are soldered to terminal portions extending from one side of the coil form, and undesired wire portions-are severed from the coil form in a fully automatic manner. Such an arrangement is shown in Weigel U.S. Pat. No. 3,227,l93, which is assigned to the same assignee as the present invention. In such prior art tuning coil arrangements, the tuning of the oscillator coil is usually accomplished by means of a tuning slug which extends into a recess in one end of the coil form and varies the inductance of the oscillator tuning coil. However, the remaining tuning coils which are spaced along the length of the coil form have heretofore been aligned manually by pushing the turns of certain coils together or moving them farther apart while observing the band-pass characteristic of the particular tuning coil unit on an oscilloscope. Such an alignment procedure requires a separate alignment or test position for each operator who must connect an individual tuner to the oscilloscope, make the proper adjustments on the oscilloscope to obtain a band-pass characteristic and then adjust the turns of the tuning coils of a particular tuning coil unit until the desired band-pass characteristic is observed on the oscilloscope. The tuning coil unit is normally aligned after the unit for each television channel has been assembled in the tuner, and when the desired band-pass characteristic is achieved the operator is informed that a particular television channel will be received correctly by that tuner. This procedure must be followed for each of the 12 television channels. Moreover, when the tuning coils are aligned by pushing turns closer together or moving them farther apart, the width of the band-pass characteristic is affected as well as the shape of the top of the band-pass characteristic, commonly called the tilt of the band-pass characteristic, and due to the interaction of these two factors, achievement of the desired characteristic is sometimes quite tedious and time consuming. Furthermore, alignment of the tuning coil unit by pushing turns closer together versus moving them farther apart has the undesirable effect of loosening the turns of the coil so that the correct alignment cannot be maintained during physical handling of the unit and the shocks due to the detent action of the tuner when in use. Also, since the wire from which the coils are wound is not completely soft, the loosened turns tend to return to their former position and the correct alignment cannot be lost even while the tuner is not being used.

It will thus be evident that skilled labor and a large amount of electronic equipment are required for each alignment station and several alignment stations are required for each assembly line of the tuner manufacturing plant. Accordingly, the cost ofaligning a tuner usually comprises a large percentage of the total manufacturing cost of the tuner. Furthermore, even with the large amount of equipment required, the results of the alignment operation performed in accordance with previous techniques has been unsatisfactory in the respects described above.

It is, therefore, an object of the present invention to provide a new and improved tuning coil unit wherein the turns of the tuning coil are deformed inwardly into a recess provided in the coil form in such manner that the deformed portions of the coil take a pennanent set at a desired inductance value.

It is another object of the present invention to provide a new and improved tuning coil unit for television tuners wherein the coil turns are wound about an elongated coil form and are physically deformed to a predetermined inductance value in such manner that the turns of the coil are tightly stretched around peripheral portions of the coil form so that said predetermined inductance value is maintained despite physical handling of the tuning coil unit and manipulation of the tuner during use.

Briefly considered, in accordance with the present invention the elongated coil form on which the tuning coils are wound is provided with a longitudinally extending recess in one side thereof, and the tuning coils are initially wound about the periphery of the coil form with portions thereof overlying this recess. Preferably, the coils are wound in a highly uniform manner by means of automatic winding apparatus so that the coils of a particular unit are spaced correctly relative to one another along the length of the coil form to give a band-pass characteristic of the desired width after the alignment operation is completed. Each individual tuning coil is then automatically and independently aligned by electrically connecting a measuring device of the tuning coil terminals on the coil form and then moving an alignment probe against the portions of the turns of the tuning coil which overlie the recess so that these portions are individually bent or deformed inwardly into the recess. As these portions are deformed into the recess the inductance of the tuning coil decreases and the measuring device is connected to terminate inward movement of the alignment probe when a desired inductance value is reached. As the alignment probe deforms the portions of the tuning coil which overlie the recess it stretches the remaining portions of the tuning coil tightly about the periphery of the coil form. Also, the inductance of the tuning coil as initially wound on the coil form is made sufficiently larger than the final value that the deformed turns will take a pennanent set within the recess at the desired inductance value. Furthermore, adjustment of the coils in a direction perpendicular to the longitudinal axis of the coil form produces a variation of the inductance of each coil without substantially affecting the width of the final band-pass characteristic, in the case of mutually coupled coils. Accordingly, each coil need only be adjusted to a particular inductance value to provide a completely aligned tuning coil unit.

The measuring device which controls deformation of the coil includes the corresponding coil of a previously aligned tuning coil unit and this previously aligned coil is employed as the frequency determining element of a first oscillator which acts as a standard reference source. The coil to be deformed is also utilized as the frequency determining element of another oscillator and the outputs of the two oscillators are heterodyned together. When the frequency of the second oscillator is equal to that of the first oscillator the measuring device terminates deformation of the coil being aligned and facilities are provided for ensuring that the coil is not further deformed thereafter. A number of tuning coils on a multicoil tuning coil unit may be simultaneously aligned to the corresponding coils on a multicoil standard unit by employing these tuning coils as frequently determining elements in oscillator circuits which operate at different frequencies. These frequencies may be quite different than the frequency of the television channel which the standard unit is designed to receive when operatively connected in the tuner and yet the aligned units will function perfectly when installed in tuners since their coils have been adjusted to have exactly the same inductance value as the standard unit. Furthermore, apparatus is provided for automatically moving unaligned tuning coil units to an alignment position, aligning a plurality of individual coils on the unit simultaneously by physical deformation as described above, and ejecting the aligned tuning coil units from the apparatus.

The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following specification taken in connection with the accompanying drawings in which:

FIG. 1 is a front view of a coil assembly alignment apparatus embodying features of the present invention;

FIG. 2 is a right side view of the apparatus of FIG. 1;

FIG. 3 is a sectional view taken along the line 3-3 of FIG. 1 and shown on an enlarged scale;

FIG. 4 is a sectional view taken along the line 44 of FIG. I and shown on an enlarged scale;

FIG. 5 is a sectional view taken along the line 5-5 of FIG. I and shown onthe same scale as FIG. 4;

FIG. 6 is a sectional view taken along the line 66 of FIG. 4;

FIG. 7. is a sectional view taken along the line 7-7 of FIG. 1 and shown on an enlarged scale;

FIG. 8 is a sectional view taken along the line 8-8 of FIG. 4 and shown on an enlarged scale;

FIG. 9 is a sectional view taken along the line 9-9 of FIG. 8;

FIG. 10 is a view similar to FIG. 9 but showing a different phase of the alignment operation;

FIG. 11 is a perspective view of the tuning coil unit support turret in the apparatus of FIG. 1;

FIG. 12 is a perspective view of a tuning coil assembly unit after it has been aligned in the apparatus of FIG. 1;

FIGS. 13, 14 and 15 are diagrammatic illustrations of different steps which'may be used in making a tuning coil unit adapted for alignment in the apparatus of FIG. 1;

FIG. 16 is a diagrammatic illustration of the tuning coil unit ready for alignment in the apparatus of FIG. 1;

FIG. 17 is a schematic diagram, partly in block diagram form, illustrating one arrangement for aligning tuning coil units with a standard reference oscillator;

FIG. I8 is a schematic diagram, partly in block diagram form, of the electrical circuitry used in conjunction with the apparatus of FIG. 1 simultaneously to align three tuning coils on a tuning coil unit to the same inductance value as corresponding coils on a reference tuning coil unit; and

FIG. 19 is a detailed circuit diagram of the electronic circuitry, shown in block diagram form in FIG. 18, for comparing one coil of the tuning coil unit with the corresponding coil of the reference tuning coil unit.

Referring now to the drawings, the automatic alignment apparatus shown in FIGS. 1 to 11, inclusive, is arranged automatically to align a plurality of coils on a tuning coil unit, such as the one shown in FIG. 12, this alignment operation being performed simultaneously on each of the tuning coils so that they are properly tuned to receive a particular television channel. Furthermore, the apparatus of FIGS. 1 to 11 is arranged automatically to align a large number of such tuning coil units in rapid succession. However, before considering the apparatus of FIGS. 1 to 11, inclusive, in detail, reference will be made to FIGS. 13 to 17, inclusive, wherein an arrangement is shown for making the unaligned tuning coil unit as well as the general method of alignment of a single coil on one of these tuning coil units.

Referring to FIGS. 13 to 15, inclusive, these figures diagrammatically illustrate one arrangement for providing a number of separate tuning coils positioned along the length of an elongated coil form of insulated material the ends of which are connected to different terminal members extending through the coil form. The arrangement shown in FIGS. 13 to 15, inclusive, corresponds generally to the arrangement shown and described in detail in Weigel U.S. Pat. No. 3,227,193, and reference may be had to this Weigel patent for a detailed description of suitable apparatus for making the unaligned tuning coil unit. In this connection it will be understood that the unaligned tuning coil unit may be made by any suitable arrangement insofar as the present invention is concerned. It is, however, important to the present invention that the tuning coils be wound on the elongated coil form in a highly uniform and accurate manner so that mutually coupled coils will have the correct spacing to provide a band-pass characteristic of the desired width after the coils have been adjusted to standard inductance values utilizing the automatic alignment apparatus of the present invention, as will be described in more detail hereinafter.

In FIG. 13 an elongated coil form of insulating material is shown positioned in a rotatable member 32 which may comprise the head stock collet of a suitable lathe-type winding apparatus by means of which the coil form 30 may be rotated. A wire feeding unit 34 is arranged to move in the direction of the arrow 36 in timed relation to rotation of the head stock 32 so that a length of wire 37, which is initially secured to the head stock at 38, is wound about the periphery of the coil form 30. A plurality of contact establishing terminal members 40 are mounted at spaced points along the length of the coil form 30 and have projecting end portions 42 which extend beyond the other side of the coil form 30 and terminate in V-shaped wire receiving notches 44. As the wire 37 is wound about the coil form 30 the wire falls into the notches 44 and is wound about the coil form between the contact making portions 40 of the terminal members. In this connection it will be understood that movement of the wire feeding member 34 is synchronized with rotation of the collet 32 so that coils of any desired 'number of turns and spacing between turns may be wound between particular terminal members, as described in more detail in Weigel U.S. Pat. No. 3,227,l93.

After the wire 37 has been'wound around the coil form 30 the coil form is moved to the position shown in FIG. 14 in which the terminal end portions 42 are immersed in a pool 46 of molten solder so that the portions of the wire 37 which are positioned within the notches in the ends of the terminal members 42 are secured to these terminal members to provide both an electrical and mechanical bond thereto.

The tuning coil unit 28 is then removed from the solder 46 and after the solder has solidified a plurality of cutting members 48 are moved downwardly, when the tuning unit 28 is supported in the position shown in FIG. 15, so that the ends of these cutting members sever the portions of the wire 37 adjacent particular ones of the terminal members. The wire portions between terminals which are not to act as tuning coils are then removed by any suitable means so as to provide a plurality of independent tuning coils spaced along the length of the coil form 30. For example, in FIG. 15, a first coil 50 is provided between the terminal members 52 and 54, a second coil 56 is provided between the terminal members 58 and 60, and

a coil comprising the coil sections 62, 64 and 66 is provided between the terminals 68 and70, the terminals 71 and 74 being connected to tapped points along the length of the coil 62, 64'and 66. In this connection, it is pointed out that only one tapped point on a coil is usually required for the RF input coil of the tuning coil unit, although two tapped points are shown, merely for purposes of illustration, in the tuning coil unit 28.

After the unwanted portions of the wire 37 have been removed by the cutting elements 48, the tuning element 28 can be removed from the coil winding apparatus. These tuning units 28 will be quite uniform from one unit to another due to the above-described arrangement for initially manufacturing the tuning coil units. Moreover, the initial manufacture of highly uniform units is an important step in the present invention since the width of the final band-pass characteristic of the aligned unit is determined primarily by the way in which the coils are initially wound on the coil form and the alignment operation to be described hereinafter has only a limited effect on the width of the band-pass characteristic. While the tuning units 28 are thus quite precisely wound as they come from the coil winding apparatus, the individual coils thereof are not precisely aligned or tuned to the desired television channel which the tuning coil unit 28 is supposed to receive, since there will be slight variations in wire size, thickness of insulation on the wire, wire tension during the winding procedure, the physical dimensions of the coil form, and other factors, which will result in small variations in the inductance of the individual tuning coils from one tuning coil unit to the next.

In accordance with an important feature of the presentinvention, a relatively deep channel or groove 72 (FIG. 12) is formed in one flat side 74 of the coil form 30. The groove 72 from the terminal member 54 to the terminal member 68 so that a portion of each turn of the coils 50, 56 and of the coil portions 62, 64 and 66 extend over the groove 72. Furthermore, the coils 50, 56, 64 and 66 are deliberately wound to have an inductance which is slightly larger than the inductance which they should have for proper tuning to the desired television channel. Then, during the alignment operation the portion of each individual turn of the respective coils which overlies the groove 72 is deformed inwardly by means of a suitable alignment probe member to reduce the inductance of the coil to the desired value.

Thus, referring to FIG. 16, an alignment probe member, indicated generally at 76, is arranged to move downwardly into engagement with the individual turns of the coil 50 when the. tuning coil unit 28 is supported on a positioning member indicated generally at 78. As the alignment probe 76 continues to move downwardly after it engages the turns of the coil 50 it deforms the individual turns of this coil into the groove 72 and hence decreases the inductance of the coil 50. When the tuning unit 28 is positioned on the support 78a pair of contacts 80 and 82 engage the terminals 54 and 52 respectively, these terminals being connected to the ends of the coil 50. A suitable measuring device is then connected between the contracts 80 and 82 so as to measure the inductance of the coil 50 as the alignment probe 76 causes the inductance of the coil 50 to decrease. When the inductance of the coil 50 is of the correct value, downward motion of the alignment probe 76 is terminated and the alignment probe 76 is moved upwardly to permit removal of the tuning unit 28. However, the turns of the coil 50 have been permanently set, due to the deforming action of the alignment probe 76, at the correct inductance value.

In a similar manner, an alignment probe 84 is arranged to contact the turns of the coil 56 and a pair of contacts 86 and 88 are connected to the terminals 60 and 58, respectively, to permit measurement of the inductance coil 56 as the align' ment probe 84 deforms the turns of the coil 56 to the correct inductance value. A plural section alignment probe 90 is provided with individual portions 92, 94 and 96 which respectively engage the turns of the coil portions 62, 64 and 66 when the alignment probe is moved downwardly into engagement therewith. In the arrangement shown in FIG. 16 only the inductance of the coils 64 and 66 is measured. Accordingly, contacts 98 and 100 are provided with engage the terminals 70 and 72 so as to measure the total inductance of the coils 64 and 66 in series, as the alignment probe 90 aligns these coils to the proper inductance value. In this connection it will be understood that the coils 64 and 66 may comprise the tapped RF input coil of the tuner, the coil 56 may comprise the tuning coil for the RF output stage of the tuner and the coil 50 may comprise the tuning coil for the mixer input circuit of the tuner. It is also pointed out that normally the coil 62 is not used for tuning coil units adapted to receive VHF channels. However, the coil 62 may be wound on the coil form and the coils 64 and 66 eliminated, in which case the coil 62 would be aligned to 40 megacycles, i.e., the IF frequency normally used for UHF reception.

In addition to the coils 50, 56 and 64, 66, an oscillator tuning coil 102 is wound around the coil form 30 and is connected between the terminal members 104 and 106 provided on this coil form, as illustrated in FIG. 12. However, the oscillator coil 102 is not permanently adjusted to a particular inductance value, since it must be varied from time to time to accomplish fine tuning of the television tuner to a particular television channel. Accordingly, the oscillator coil 102 is wound about a portion of the coil form 30 which does not include the groove 72 and a tuning slug I08 is arranged to extend into the end of the coil form 30 to a point within the coil 102 so that longitudinal movement of the slug I08 changes the inductance of the coil 102. The tuning slug 108 may be provided with a suitable pinion gear 110 on the end thereof by means of which a fine tuning adjustment may be made by any suitable arrangement, such as the arrangements described, for

example, in Badger US. Pat. Nos. 3,2l8,588 and 3,l83,726, which are assigned to the same assignee as the present invention.

In accordance with an important feature of the present invcntion, movement of the alignment probes 84, 76 and is individually controlled by the measuring devices respectively connected to the contacts 80, 82, the contacts 86, 88 and the contacts 98, so that downward movement of the alignment probes is terminated at the exact point at which the respective tuning coils have the proper inductance for accurate tuning to the desired television channel. A suitable arrangement for controlling movement of the alignment probe 76 to obtain the desired inductance for the coil 50 is shown in FIG. 17. Referring to this figure, the contacts 80 and 82 are shown connected to the coil 50 on the tuning coil unit 28. In the measuring device of FIG. 17, the tuning coil 50 acts as the frequency determining element of an oscillator, which oscillator forms a part of the measuring device, the tuning coil being utilized as the inductive branch of the oscillator tank circuit. More particularly, a variable capacitor is connected across the contacts 80, 82 so that the combination of the coil 50 and variable capacitor 110 forms an oscillatory tank circuit. One end of the capacitor is connected through a feedback capacitor 112 to the plate of an oscillator tube 114 and the other end of the variable capacitor 110 is connected through a capacitor 116 to the grid of the tube 114 and through the resistor 118 to the cathode of the tube I14, this cathode being connected to ground. A plate load resistor 120 is connected from the plate of the tube 114 to a suitable B plus supply.

When an unaligned tuning coil unit is placed in the measuring device and the contacts 54, 52 are connected to the contacts 80, 82 the oscillator 114 is arranged to oscillate at a frequency determined by the inductance of the tuning coil 50 and the adjustment of the capacitor 110. The frequency of oscillation of the tube 114 with the coil 50 connected in circuit is initially adjusted, by variation of the capacitor 110, so that this frequency is within 6 megacycles of the frequency of a standard reference oscillator 12, as will be described in more detail hereinafter in connection with the initial alignment adjustment of the apparatus of FIG. 17. In the arrangement of FIG. 17 the oscillator 122 may comprise any suitable type of stable oscillator which provides a high frequency signal, although the frequency of this oscillator need not correspond to the frequency of the television channel which the tuning coil 50 is to accept, as will be described in more detail hereinafter.

The signal from the oscillator tube 114 is coupled through the capacitor 124 to a mixer 126, and the signal from the oscillator 122 is coupled through a capacitor 128 to the mixer 126. The heterodyne or beat frequency output of the mixer 126 is transmitted through a 6 megacycle low-pass filter 129 to a wide band amplifier 130. The amplified signal produced in the output of the amplifier 130 is supplied through a high pass filter 132 which has a low frequency cutoff of I00 kilocycles to a DC amplifier 134 the output of which is supplied to a relay 136 which controls the supply of current to an alignment probe driving motor indicated generally at 138. The motor 138 is reversible as indicated by the windings I40 thereof. The motor 138 is arranged mechanically to drive a cam 142 so that the cam I42 rotates at a relatively slow speed in the direction of the arrow 144 when the motor 138 is energized. The roller 146 which is positioned on the upper end of the vertically movable alignment probe 76 engages the surface of the cam 142 so that as this cam rotates counterclockwise, as viewed in FIG. 17, the alignment probe 76 is moved downwardly. The end of the alignment probe 76 engages the portion of each turn of the coil 50 which is positioned over the recess 72 in the coil form 30 and hence can deform these portions of the coil 50 inwardly. As this occurs the inductance of the coil 50 decreases with the result that the frequency of the oscillator I44 increases since the resonant frequency of the tank circuit 50, I10 increases with decreasing inductance of the coil 50.

As the frequency of the oscillator 114 comes closer to the frequency of the reference oscillator 122 the beat frequency also decreases and when this beat frequency component becomes less than 100 kilocycles, no signal is transmitted through the filter 132. The relay 136 is thereby deenergized so that the motor 138 is immediately reversed, by means to be described in more detail hereinafter, and the alignment probe 76 is moved upwardly away from the tuning coil 50. The motor 138 and its associated gearing are preferably of low inertia. However, a certain period of time is required to stop the motor, and hence terminate downward movement of the alignment probe, after power is removed from the motor. By providing the high pass filter 132, current is removed from the motor 138 a sufficient time interval before the zero beat point to permit the motor to stop in the vicinity of zero beat at which point the frequency of the oscillator 114 is exactly equal to the oscillator 122. In this connection it is pointed out that even if the motor stops at a point 100 kilocycles away from zero beat, the accuracy of alignment is 0.l percent when the frequency of the oscillator 122 is 100 megacycles. The filter 132 also provides a dead band within which the motor 138 may be reversed in direction. If the relay 136 were cut off only momentarily at the zero beat point, the inertia of the motor 138 would carry it on through the zero beat point so that the relay will again close and continue the downward movement of the alignment probe. The high pass filter 132 thus provides a dead band of 200 kilocycles centered about the zero beat point within which the motor 138 may reverse. In addition, the relay 136 may control energization of the oscillator 114 to insure I that the motor 138 is not started again in the same direction,

as will be described hereinafter in connection with the circuit arrangement of FIGS. 18 and 19.

The turns of the coil 50 have thus been given a permanent set by the alignment probe 76-and hence remain in the position to which they were deformed by the'probe 76 after the probe is removed. Accordingly, the coil 50 is now tuned precisely to an inductance value such that when combined with the capacity of the capacitor 110 the resonant frequency thereof is equalito the frequency of the oscillator 122. In order to have this value of inductance be the correct one for tuning to the desired television channel the capacitor 110 and oscillator 122 must be initially adjusted so that tuning coil units 1 which are thereafter aligned by the apparatus of FIG. 17 will be precisely tuned'to a particular channel. To this end, one of the tuning coil units 28 which has been wound by the abovedescribed apparatus, is precisely aligned to receive a particular television channel. Such alignment can be done by adjusting the turns manually, while the unit is operatively connected in the tuner, and observing the resultant band-pass charac- 1 teristic of the tuner. When the desired band-pass characparticular channel and this unit can then be used as a reference or frequency standard. The coil of the manually aligned referenceunit is then placed in contact with the terminals 80, 82 of the apparatus of FIG. 17 and the oscillator 122 is adjusted to generate a high frequency signal. The frequency'ofthis signal need not be the same as the frequency of the channel to which the manually aligned unit is tuned. For example, if the manually aligned reference unit is tuned to channel 2, the oscillator 122 may have a frequency of 40 megacycles whereas if the reference unit is tuned to channel 13 the oscillator 122 may have a frequency of 100 megacycles, i.e., considerably below the actual channel 13 band of 210-216 megacycles. The capacitor 110 is then adjusted until the heterodyne or beat frequency from the two oscillators 110 and 122 is zero. Since the relay 136 cuts ofi' at 100 ltilocycles from the zero beat point, due to the abovedescribed action of the high pass filter 132, it is necessary to make this initial alignment set up with the manually aligned reference unit at a point ahead of the filter 132. Accordingly, the output of the wide band amplifier 130 may be supplied to any suitable indicating device such as a loudspeaker, or an AC nected in parallel with these capacitors and the capacitors ad-.

voltmeter, and the capacitor 110 is adjusted until a zero beat is obtained between the oscillators 114 and 122. The manually aligned reference unit is then removed from the terminals and 82 and the coil 50 of an unaligned unit is placed in contact therewith. As stated heretofore, the coils as originally wound have an inductance which is greater than the value at which the coil is precisely tuned to the desired channel so that the frequency of the oscillator 114 when the unaligned unit is first inserted will always be lower than the frequency of the oscillator 122. Therefore, as the alignment probe 76 deforms the turns of the unaligned coil 50 inwardly it decreases the inductance of this coil and increases the frequency of the oscillator 114. This continues until the relay 136 cuts out at which time the coil 50 of the unit being aligned will have exactly the same inductance as the coil 50 of the manually aligned reference unit. This is because the capacitor 110 was initially adjusted to give zero beat with the oscillator 122 when the coil 50 of the reference unit was connected across the capacitor. It will thus be noted that the apparatus of FIG. 17 does not actually measure the inductance of the coil under alignment in microhenries, but simply adjusts the inductance of this coil until it is the same as the inductance of the corresponding coil on the reference unit. However, this comparison is precisely made and is satisfactory to align even channel 13 tuning coils which comprise only one or two turns and have a very low inductance when measured in microhenries. Furthermore, the alignment operation may be carried out at a frequency considerably lower than the channel operating frequency, for example at megacycles for channel 13 coils, and still the units aligned by the apparatus of FIG. 17, when inserted into the tuner, will be-tuned precisely to the desired channel in the same manner as the manually aligned reference unit. In this connection, it will be understood that after the aligned tuning coil units have been placed in the tuner the tuner chassis or base must be adjusted to provide the desired bandpass characteristic since it is the circuit capacities of the tuner chassis which combine with the coils on a particular tuning coil unit to provide reception of a particular television channel. This alignment of the tuner base may be made in a conventional manner, as by adjusting various trimmers or "gimmick wires on the chassis while observing the overall bandpass characteristic of the tuner. However, since tuning coil units aligned in accordance with the present invention are highly uniform and are precisely adjusted to the correct value of inductance, the alignment of the tuner base is also simplified.

. Additional alignment units, indicated generally at 150 and 152 are provided for the tuning coils 56 and the coil 66, 64 on each tuning coil unit, these alignment units being similar to the above-described unit for the coil 50 and operating the respective alignment probe members 84 and 90 to align the respective tuning coils to the desired frequencies.

Each of the alignment units 150 and 152 includes a variable capacitor similar to the capacitor and the corresponding coils on the manually aligned reference unit are initially eonjusted for exact zero beat with the oscillator 122, which is connected to supplyall alignment units, as described in detail heretofore in connection with the initial adjustments for the' coil '50. In this connection, it will be understood that the capacitors 110 are adjusted only at the start of an alignment operation and once adjusted to give zero beat with a reference coil unit they remain fixed'while thousands of tuning coil units are being aligned. Y I

If desired, the alignment of the three coils on'the tuning unit 28 may be performed in sequence, using the same standard reference oscillator 122, after the capacitor 110 of each alignment unit has been initially adjusted to the correct value. When this is done the low-pass filter 129 is not required since only one signal is produced by a tuning coil oscillator 114 at any given time. However, in the preferred arrangement of the apparatus of FIG. 1, the individual coils on the reference tuning coil units themselves are utilized to control the frequency of separate oscillators acting as frequergcy standards. These oscillators are preferably spaced more than 6 meg'acycles apart so that the filter 129 in each alignment section will block out signals from the other oscillators and prevent interference therebetween, as will be described in more detail hereinafter. Accordingly, in the apparatus of FIG. 1, the alignment of all of the tuning coils on a given tuning coil unit 28 may be performed simultaneously to minimize the time required to align a particular tuning coil unit.

Referring now to the alignment apparatus of FIGS. 1 to 11, inclusive, this apparatus comprises a pair of vertically extending side members 160 and 162 which are mounted on a base member 164 and are connected together at the top end thereof by means ofa top member 166. The alignment probe 76 is mounted on the bottom end of a vertically extending bar 168, the bar 168 being journaled in the top plate 166 and in a crossbar structure, comprising the crossbar 170 and plate 172, which acts as a guide for the bar 168. A small reversible electric motor 174 is mounted on the upper side member 176 and a cam member 178, similar to the cam 142 of FIG. 17, is connected to the output shaft 180 of a suitable gear reduction mechanism which is driven by the motor 170. The cam 178 engages a roller 182 which is positioned on a pin 184 adjustably connected to the vertically slidable bar 168.

In a similar manner, the alignment probe 84 is connected to the lower end of a vertically slidable bar 186 and an electric motor 188 (FIG. 2), which is mounted on the rear edge of the side members 160 and 176, is arranged to drive a cam 190 which is connected to the output shaft 192 of a gear reduction mechanism associated with the motor 188. The cam 190 engages a roller 194 which is rotatably mounted on a pin 196 (FIG. 3) which is mounted on an adjustable plate 198. The plate 198 is secured to the slide bar 186 by means of the bolts 200 which are positioned in elongated slots 202 in the bar 186 to permit a limited vertical adjustment of the roller 194, so that the alignment probe 84 when in its lowermost position does not strike the bottom of the groove 72 of a tuning coil unit 28 under alignment.

The alignment probe 90 is connected to the bottom end of a vertically slidable bar 204 and an electric motor 206 is mounted on the side member 160. A cam 208 is mounted on the end of a gear reduction shaft 210 associated with the motor 206 and the cam 208 engages the roller 212 which is likewise adjustably connected to the slide bar 204.

Each of the slide bars 168, 186 and 204 is normally held in its uppermost position by means of the coil springs 214, 216 and 218. More particularly, referring to the bar 186, a stud 220 is slidably mounted in the top plate 166 and is connected to the upper end of the bar 186, the stud 220 being provided with a flange 222. The coil spring 216 is then positioned between the top plate 166 and the flange 222. The stud 220 is provided with an adjustable nut 224 on the upper end thereof which engages the button 226 of a microswitch assembly indicated generally at 228. The microswitch assembly is mounted on a plate 230 which is in turn supported on the posts 232 which rest on the top plate 166. A cover plate 234 is secured to the upper end of the posts 232 to prevent damage to the terminals 236 of the microswitch housing 228. The switch 228, and the switches 238 and 240 corresponding to the probes 76 and 90, respectively, are employed to control the respective driving motor circuits, as will be described in more detail hereinafter in connection with the circuit diagram of FIG. 18 for the apparatus of FIGS. 1 to 11, inclusive.

In order to provide a structure into which individual tuning coil units may be rapidly loaded, moved to an alignment position and then ejected, there is provided a rotatable turret indicated generally at 240 (FIG. 11). The turret 240 comprises a central sleeve portion 242 and a plurality of transversely extending disc portions 244, 246, 248, 250, 252, 254, 256 and 258 and 260. Each of these discs is generally in the form of a hexagon and the individual flat sides of each hexagon-shaped disc are aligned so that they collectively form a support for a tuning coil unit while the terminals thereof extend into the area between the discs. Furthermore, the width of certain of these discs is made equal to the length of the corresponding tuning coil on the tuning coil unit 28 which is to be aligned to provide a suitable support for the unit 28 in the areas thereof which are engaged by the probes 76, 84 and 90. Thus, referring to FIG. 8, the disc 248 has a width corresponding to the length of the coil 50 along the coil form 30 of the tuning coil unit 28; the disc 250 has a width corresponding to the tuning coil 56; and the discs 254, 256 and 258 have widths corresponding to the coil sections 66, 64 and 62, respectively. The disc 246 has a width corresponding to the oscillator coil 102 and the discs 244 and 260 correspond to the outer extremities of the tuning coil unit 28.

As will be readily apparent from FIG. 8, the terminals 42 of the tuning coil unit 28 extend into the recesses provided between the'discs of the turret 240 while at the same time the alignment probes 76, 84 and are permitted to move downwardly into engagement with the coil portions over the recess 72 while the opposite side of the coil form is supported by the discs 248, 250, etc.

In order to position the tuning coil unit 28 accurately with respect to the alignment probes, the discs 244, 248, 252 and 260 are each provided with shoulders 244a, 248a, 252a and 260a, on each of the six sides of the disc, against which a particular tuning coil unit may be held during the alignment operation. Moreover, a series of six spring clips 270 are secured one to each face of the disc 252 by means of the screws 272, the clips 270 urging the tuning coil unit 28 against the shoulders 244a, 248a, etc. during the alignment operation. The turret 240 is pinned to a shaft 274 which is rotatably mounted in a pair of bearings 276 and 278 mounted on the side members 162 and 160, respectively. A Geneva wheel 280 is secured to one end of the shaft 274. A'bracket 282 is mounted on the side member 162 by means of the posts 284, and a drive motor 286 is mounted on the bracket 282. A bracket 288 is mounted on the side member by means of the posts 290 and a control shaft 292 is rotatably mounted in the bracket 288. The left-hand end of the shaft 292 is connected to the shaft 294 of the gear train associated with the driving motor 286 through a universal coupling including a pin 296 on the shaft 292 and a slotted hub member 298 which is mounted on the shaft 294 and is secured to the shaft 294 by means of the setscrew 300. The hub 298 is provided with a flange 302 the outer tip of which carries a pin 304 which is adapted to engage the slots 306 of the Geneva wheel 280 when the shaft 294 is rotated. Accordingly, when the drive motor 286 is energized, each revolution of the output shaft 294 causes the turret 240 to rotate one-sixth of a revolution so as to bring a different tuning coil unit, which has been mounted thereon, into the alignment position. In this connection it is pointed out that the portions 308 of the Geneva wheel 280 between the slots 286 are of arcuate form corresponding to the periphery 310 of the flange 301. Furthermore, the flange 302 overlaps the Geneva wheel 280, as is best illustrated in FIG. 6 so that the periphery 310 of the flange 302 engages the curved surface 308 of the Geneva wheel 280 during the period when the shaft 294 is rotating to bring the pin 304 in position to engage the next slot 306. Accordingly, the turret 240 is locked in the desired alignment position between actuations of the Geneva wheel 280. It will be noted that the flange 302 is provided with an undercut portion defined by the shoulder 312 to provide clearance for that portion of the flange 302 which passes by the Geneva wheel 280. The gear reduction associated with the motor 286 is so arranged that the turret 240 is held stationary in the alignment position for a period of approximately 3 seconds after which the pin 304 engages one of the slots 306 and rapidly moves the turret 240 to bring the next tuning coil into position.

In order to provide an arrangement for loading unaligned tuning coil units into the turret 240 in a simple and reliable manner a pair of side extension members 316 and 318 are mounted on the side members 162 and 160, respectively, and a pair of guide members 320 and 322 are secured on the inner 280, the upper edges 326 of the members 320 and 322 are in alignment with the shoulders 244a, 248a, 252a and 260a of the respective disc portions of the turret 240. Accordingly, a tuning coil unit may be slid down the upper edges 226 of the members 320 into position on the respective discs of the turret 240 and wedged against the spring clip 270. When the turret 240 is next moved by actuation of the Geneva wheel 280 this tuning coil unit is moved upwardly to the alignment position beneath the alignment probes 76, 84 and 90. The beveled shoulders 316a and 318a of the members 316 and 318 also facilitate insertion of tuning coil units into the turret 240.

In order to eject an'aligned tuning coil unit from the turret 240, an ejector member 330 is pivotally mounted on a shaft 332 which extends between the brackets 282 and 288. The ejector member 330 comprises a hub portion 334 which is secured to the shaft 332 by means of the screw 336 and a pair of ejector plates 338 and 340 are secured to the ends of the hub 334. The plates 338 and 340 are provided with ejector fingers 342 which are normally positioned adjacent the central sleeve portion 242 of the discs of the turret 240.

More particularly, the finger 342 of the plate 338 is positioned approximately midway between the flanges 246 and" 248 at a point where this finger does not interfere with the terminals 42 of a tuning coil unit. In a similar manner the finger 342 of the plate 340 is positioned between the flanges 252 and 254, again at a point which does not interfere with a terminal 42 of the tuning coil unit 28. Accordingly, the turret 240 may be rotated so that the aligned tuning coil unit may be brought to a position diametrically opposite the alignment probe position without the fingers 342 engaging the tuning coil unit. However, when the ejector member 330 is pivoted downwardly, the fingers 342 thereof engage the aligned tuning coil unit at the points indicated and move the aligned tuning coil unit from the spring clip 270 whereupon the aligned tuning coil unit strikes the deflector plate 344 and may be dropped into a suitable collection bin (not shown).

In order to pivot the ejector member 330 in timed relation to the alignment probe operation, a cam member 346 is secured to the shaft 292. Furthermore, a shaft 348 is secured between the plates 338 and 340 at a point somewhat below the shaft 292. Accordingly, as the shaft 292 is rotated, the cam 346 engages the shaft 348 and pivots the ejector member 330 about the shaft 332 so that the fingers 342 are moved downwardly to eject the particular aligned tuning coil unit which has been moved to the position diametrically opposite the alignment probe position. When the cam 346 has been moved past the shaft 348 the ejector member 330 is moved back to the normal position shown in FIG. 4 by means of a coil spring 350 which is secured between a flange 352 on the shaft 332 and the bearing housing 354 for the shaft 292 which is mounted on the bracket 288.

In order to establish electrical contact to the ends of each tuning coil which is to be aligned at the alignment probe position, a terminal block 360 is secured to a plate 362 by means of the screws 363, the plate 362 being mounted on the side members 162 and 160 by means of the screws 364. Each of the contacts 80, 82, 86, 88, 98 and 100 is secured in an individual notch provided in the bottom edge of the terminal block 360 by means of the screws 366 (FIG. 4). A part of the electronic circuitry of the measuring devices provided for each alignment probe is contained in a housing 368 also mounted on the plate 362, the housing 368 having an opening 370 in the bottom wall thereof to permit connection of the circuitry within the housing 368 to the end portions 372 of the contact fingers 86 shown in FIG. 4.

As best illustrated in FIG 9, each .of the contacts, such as the contact 86, is in the form of a spring arm having an arcuateportion 374 which is positioned to engage the beveled edge of the corresponding contact, such as the contact 60, on the tuning coil unit 28, when this unit is moved to the alignment probe position. The alignment probe, such as the member 84, is made of insulating material and is secured to the vertically slidable bar, such as the bar 186, by means of a tongue portion 376 which extends upwardly into the split end of the bar 186 and is secured thereto by means of the screw 378. The alignment probe 86 is tapered to provide a relatively thin end portion 380 which has a rounded end of somewhat smaller radius than the groove 72 in the tuning coil unit 28. Accordingly, as the alignment probe 84 is moved downwardly, it engages the turns of the coil 56 which are positioned over the recess 72 and deforms them inwardly by the proper amount to provide the correct inductance.

In accordance with an important feature of the invention, the inward deformation of the individual turns of the tuning coil by means of the rounded end 380 of the alignment probe 84 has the additional advantage that the turns of the tuning coil are tightly stretched around the periphery of the coil form 30 during the alignment operation so that the tuning coils are permanently aligned to the correct channel and will not become mistuned during handling, physical shock and vibration when positioned in the turret of the television tuner, etc. As the turns of the tuning coil are initially wound on the coil form 30, for example by means of the arrangement shown in H0. 13, the individual turns are somewhat loosely positioned around the coil form 30 since the wire cannot be sharply crimped at the corners of the rectangular coil form. Accordingly, the turns of the coil, such as the coil 56 shown in FIG. 9, are somewhat loosely positioned on the coil form and A i may be moved sidewardly. In fact, as stated heretofore, sideward movement of the individual turns of a tuning coil has been employed in the past to align the coil to the desired channel frequency. Furthermore, the midportions of the turns do not lie flat against the coil but instead have a hump between each corner. This is particularly evident when a heavy wire is used for the coil, as in the case of higher channel tuning coil units. However, when the rounded end 380 of the alignment probe 84 moves downwardly and pushes the turns of the coil 56 into the groove 72, the initial action is to press the wire flat against the bottom of the coil form 30 and stretch the portions of the turns which engage the sides of the coil form tightly against the coil form in the manner shown in FlG. 10. The groove 72 is provided with a depth sufficient to permit this tightening action and the adjustment of the coil to the same inductance as the standard reference unit without causing the crimped portions of the turns of the coil 56 to strike the bottom of the groove 72. Furthermore, as pointed out above, the inductance of the coil 50 as initially wound on the coil form 30 is arranged to be somewhat larger than the desired tuning coil inductance which will tune the circuit to the desired television channel. Accordingly, the probe end 380 must deform or crimp the turns of the coil 56 inwardly by a certain minimum amount to decrease the inductance of this coil to the proper inductance value. This minimum amount of crimping is made sufficient to ensure that the wire will overcome its natural tendency to spring back to its original position and will take a permanent set at the desired inductance value. ln this connection, it will be understood that the initial slack of the individual turns'is taken up without causing the wire itself to stretch. In addition, the smallest size wire may be stretched approximately 50 mils without breaking. The maximum travel of the probe 380 is arranged so that the desired inductance is reached before the elastic limit of the wire comprising the stretched turns is exceeded. For example, when the coil form 30 is of 0.375

inch square cross section, the groove 72 may have a depth of g 0.050 inch with satisfactory alignment on all-channels when wire of the appropriate size is employed for the coils of the tuning unit 28. It is also pointed out that there will be a slight springback of the wire over the groove 72 when the probeend 380 is removed. However, this springback tends to be very small, since the turns are crimped inwardly into the groove 72 by a certain minimum amount. Also, the springback will be essentially the same with all aligned units. If desired, the alignment probe may be arranged to overshoot the zero beat point slightly, by appropriate choice of the inertia of the drive motor and its associated gearing, so that when the probe is removed the wire springs back an amount just equal to the overshoot so that the position at which the wire is permanently set is exactly at the zero beat point. However, as pointed out above, an accuracy of 0.1 percent is achieved even if the coil is set at a point 100 kiloeycles from the zero beat point.

In order to provide timing signals during the alignment cycle and in accordance with movement with the Geneva wheel 280, a plurality of cam members are provided on the shaft 292. More particularly, a first cam member 390 having a lobe 392 is mounted on the shaft 292 and is arranged to actuate the roller 394 of a microswitch 396. A second cam 398 which is spaced along the shaft 292 by means of the spacer 400 is pro vided with a lobe 402 which is adapted to engage the roller 404 of a microswitch 406. The cams 390 and 398 are held in spaced relation by means of the bolt 416. In FIG. 18 of the drawings there is shown the circuit interconnections for the alignment motors 170, 188 and 206 and the Geneva drive motor 286 with electronic circuitry, a part of which is included in the housing 368, whereby the turret 240 may be driven, and the individual tuning coil units loaded into this turret can be automatically aligned in a highly efficient and rapid manner. In the circuit arrangement of FIG. W a reference tuning coil unit which has been previously aligned by any suitable method to have the desired overall band-pass characteristic and the desired inductance values for each coil, as described previously, is utilized in a suitable oscillator circuit as a frequency determining device to develop the reference oscillations corresponding to the reference oscillator I22 of FIG. 17. Such an arrangement is particularly advantageous for the mass production of television tuners since there will be minor variations in tuning coil units for a particular channel due to different requirements by various television set manufacturers. For example, the band width requirements may vary, with different set manufacturers; resistance wire may be used in some tuning coil units and not in others, and other variations may occur. By simply placing a tuning coil unit which has the correct specifications for a particular set manufacturer and which has been previously aligned as a standard, or reference unit, in the alignment apparatus and initially adjusting the electronic circuitry to align additional, similarly wound, tuning coil units to have the same inductance characteristics, the alignment apparatus is thereby capable of handling the large variety of requirements in tuning coil units which arise in television tuner manufacture.

In FIG. 18, the Geneva drive motor 286 is illustrated as having series connected windings 420 and 424 to which a conventional alternating current may be supplied through the main switch 422. One end of the winding 424 is connected to the contact 426 of the microswitch 406 which is associated with the cam 398. A capacitor 428 is connected across the winding 420 and 424. The motor 286 is arranged to drive the element 302 which carries the pin 304 and actuates the Geneva wheel 280 one step for every revolution of the gear reduction output shaft 294. Accordingly, a new unaligned tuning coil unit is moved into the alignment position for each revolution of the shaft 294. Since the shaft 296 is connected to the shaft 294, the cams 390 and 398 also rotate one revolution for each step of the Geneva wheel 280. The pin 304 is shown in FIG. 18 as just about to enter one of the slots of the Geneva wheel 280 and approximately one-fourth revolution of the shaft 294 thereafter a new unaligned tuning coil unit has been moved into alignment probe position. When this occurs, the lobe 392 on the cam 390 closes the microswitch 396 and applies voltage to the coil 430 of a relay having three sets of contacts 432,

434 and 436, one for each of the alignment units corresponding to the probes 76, 84 and 90. In this connection, it is pointed out that only the alignment unit for the probe 76 is shown in detail in FIG. 18, it being understood that similar alignment units are provided for the other probes 84 and 90.

When the relay coil 430 is energized, a minus 24-volt supply voltage is connected by way of the conductor 438 to an unaligned coil unit oscillator and mixer 440. The tuning coil 50 of the unaligned unit 28 which has just been moved to the alignment position is connected to the input contacts 80 and 82 of the oscillator and mixer 440. The corresponding coil 50a of a precisely aligned reference tuning coil unit is also connected to the input terminals 80a and 82a of a standard coil unit oscillator and amplifier 442 at the start of a particular alignment operation and remains connected to these terminals during the entire period when tuning coil units of the same type as the reference unit are automatically being aligned by the apparatus of FIGS. 1 to 11, inclusive. In this connection it will be understood that when a tuning coil unit is moved to the alignment position, the other two tuning coils 56 and 66, 64 which are also to be aligned during the same alignment cycle, are connected to circuits corresponding to the oscillator and mixer 440 in the alignment units provided for the probes 84 and 90' Also, the coils 56a and 64a, 66a of the standard reference coil unit are connected to the input of the circuits corresponding to the oscillator and amplifier 442 in the alignment units for the probes 84 and 90 during the period when a group of tuning coil units is being aligned to this particular reference tuning coil unit. It will also be understood that as soon as the relay coil 430 is energized a suitable supply voltage is supplied over the conductor 444 to the alignment unit for the probe 90 and over the conductor 445 to the alignment unit for the probe 84 so that each alignment operation can proceed simultaneously and all three coils of thetuning unit can be aligned during one alignment cycle.

Each of the units 440 associated with each probe unit is provided with a mixer, similar to the mixer 126 of FIG. 17 and the amplified oscillations developed by the unit 442 are continuously supplied to this mixer. Accordingly, as soon as the supply voltage is impressed upon each of the units 440 an output signal is developed equal to the difference in frequency between the oscillators in the units 440 and 442, and this beat frequency signal is supplied to the unit 450 which includes the filters, wide band amplifier, rectifier and DC amplifier corresponding to the units 128, 130, 132 and 134 of FIG. 17. The output developed by the unit 450 is supplied to the coil 452 of a relay provided with the contacts 453 to 460, inclusive. When the relay coil 452 is energized, the contacts 453 and 454 are closed so that minus 24 volts is supplied by way of the conductor 460 to the unit 440, thereby to maintain this unit energized after the microswitch 396 is opened as the cam 390 continues to rotate. Accordingly, the contacts 453 and 454 constitute a holding circuit which maintains the unit 440 energized as the alignment cycle proceeds.

When the relay coil 452 is energized, the contacts 459 and 460 are closed so that AC voltage is supplied by way of the conductor 464, the contacts 459, 460 and one winding 466 of the series connected windings 466 and 470 of the motor 170 to the other side of the AC line, a capacitor 472 being connected across the windings 466 and 470. When this occurs the motor 170 drives the cam 178 in the direction to move the slide bar 168 and the alignment probe 76 downwardly toward the tuning coil unit 28 which is immediately therebcneath. In this connection it will be noted that the same tuning coil unit is illustrated electrically as connected to the input of the unit 440 and is also shown physically as being beneath the probe 76, it being understood that in actuality the arrangement is as described heretofore in connection with FIG. 8, for example, of the drawings.

As the alignment probe 76 moves downwardly it engages the turns of the coil 50 which are positioned over the groove 72 and deforms these turns inwardly so as to reduce the inductance of the coil 50. As the inductance of the coil 50 decreases the frequency of the oscillator in the unit 440 which includes the coil 50 increases and the beat frequency output of the unit 440 correspondingly decreases since the output frequency of the unit 442 remains constant. When the beat frequency output of the unit 440 decreases to a point where it is within 100 kilocycles of zero beat, the high pass filter in the unit 450 cuts off the output to the relay 452 so that this relay is deenergized. When this occurs, the contacts 458 and 459 are closed, so that AC voltage is supplied by way of the conductor 464 and the contacts 458, 459 to the upper end of the winding 470 of the motor 170. This causes the motor 170 rapidly to reverse and rotate the cam 178 in the opposite direction so that the alignment probe 76 is moved upwardly under the force of the coil spring 214.

When the slide bar 168 has been returned to its initial position the contacts 474, 476 and 478, 480 of the microswitch 238 are closed. When the contacts 474 and 476 are closed, a shunting resistor 482 is connected across the windings 466 and 470 over a path which includes the contacts 474, 476, the resistor 482, the . contacts 456 and 455, and the conductor 484. When the winding 470 is thus short circuited, the motor 170 is immediately stopped and the alignment cycle for the training coil 50 is completed. During this same alignment cycle, the probes 84 and 90 have also been moved downwardly to deform the coils 56 and 66, 64, respectively, and are returned to their initial positions.

It will be noted that when the relay coil 452 is dcenergized the contacts 453, 454 thereof are opened. When these contacts open they remove the minus 24-volt supply voltage from the unit 440. The oscillator which includes the coil 50, and the mixer, in the unit 440 are thus rendered inoperative when the relay 452 is cut off, i.e., as soon as the beat frequency signal becomes less than 100 kilocycies. If the motor 170 has an excessive overshoot while it is being reversed and moves the probe 76 downwardly by an amount such that the oscillator which includes the coil 50 would be more than 100 kilocycles on the other side of zero beat, this could reenergize the relay 452 and cause the motor 170 to continue to rotate in the same direction without reversing. However, by removing supply voltage from the unit 440 as soon as the relay 452 is deenergized no beat frequency signal can thereafter be developed since both the oscillator and mixer in the unit 440 are rendered inoperative. The relay 452 is thus positively prevented from being reenergized and reversal of the motor 170 and upward movement of the alignment probe are ensured.

in the event that any one of the alignment probes 76, 84 and 90, for example the alignment probe 76, is not returned to its initial position, the contacts 480, 486 of the microswitch 238 remain closed. Just before the pin 312 engages the Geneva wheel 270 to move a new tuning coil unit into the alignment probe position, the lobe 402 on the cam 398 closes the microswitch 406. This places a short circuit across the windings 420 and 424 and stops the Geneva drive motor 286. The main switch 422 may then be opened and the cause of the difficulty ascertained before the alignment operation is recommenced. The cam 402 and the associated microswitch contacts thus comprise a checking circuit which verifies that all alignment probes are out of the way before the turret 240 is rotated to bring the next tuning coil unit to the alignment position.

In FIG. 19 there is shown the detailed circuit arrangement of the units 440, 442 and 450 which are shown in block diagram form in FIG. 18 for the alignment probe 76. Referring to FIG. 19, when a tuning coil unit is moved to the alignment position, the coil 50 thereof is connected to the input terminals 80 and 82 of the unit 440 across which terminals is connected a variable capacitor 500. The coil 50 and capacitor 500 act as a tank circuit for an oscillator which includes a transistor 502, the collector of which is connected to ground and the emitter of which is connected to ground through a bypass capacitor 504 and through a resistor 506 to a minus supply potential point 508. The minus 24-volt supply which is connected to the unit 440 over the conductor 438 at the start of each alignment cycle, as described in detail heretofore in connection with FIG. 18," is filtered in a filtering arrangement which includes the bypasscapacitors 510, 512 and-514 and the series resistors 516 and 5181 The ungrounded end of the coil 50 and capacitor 500 is connected to the base of the transistor 502 through a parallel combination of a resistor 520 and capacitor 522, this base electrode also being connected to the supply potential point 508 through the resistor 524. A capacitor 523 is connected between the emitter and base of the transistor 502 to provide feedback for sustained oscillation. Accordingly, when a minus 24-volt supply voltage is applied to the unit 440 the oscillator 502 develops oscillations at a frequency determined by the inductance of the coil 50 and the adjustment of the capacitor 500. These oscillations are coupled by way of a capacitor 526 to the base of a transistor 528 the collector of which is connected in common with the collector of another transistor 530 to ground through the common resistor 532. The emitters of the two transistors 528 and 530 are connected through a common resistor 534 to the junction of the resistors 516 and 518. The base of the transistor 528 is connected to ground through a resistor 536 and through a resistor 538 to this same supply point. ln the same manner, the base of the transistor 530 is connected to ground through a resistor 540 and through a resistor 542 to the common supply potential point.

The tuning coil 50a of the reference tuning coil unit is connected to the contacts a and 82a of the unit 442 at the start of an alignment operation in which a number of tuning coil units are to be aligned to this standard. A variable capacitor 544 is connected across the contacts 80a and 82a and the contact 80a is connected through a parallel combination of a resistor 546 and a capacitor 548 to the base of a transistor 550, the collector of which is connected to ground. The emitter of the transistor 550 is connected to ground through a bypass capacitor 552 and through a load resistor 554 to a minus 14- volt potential which is continuously supplied to the unit 442. The base of the transistor 550 is also connected through the resistor 556, to the minus l4-volt supply and a capacitor 557 is connected between emitter and base so that sustained oscillations may be developed in the tank circuit 50a, 544.

As soon as the reference tuning coil unit is placed in circuit with the contacts 800 and 82a the transistor 550 oscillates at a frequency detennined by the inductance of the coil 50a and the adjustment of the capacitor 544. These oscillations are coupled through a capacitor 560 to the base of a transistor 562, which acts as a buffer and variable gain amplifier, this base being also connected to ground through the resistor 564 and through a resistor 566 and a potentiometer 568 to the minus l4-volt supply. The collector of the transistor 562 is connected to ground through a tuned circuit which includes the capacitor 570 and the variable primary winding 572 of a step down transformer, this winding being tunable to the frequency of the oscillations produced by the oscillator 550 by variation of the inductance of the winding 572. The emitter of the transistor 562 is connected to ground through a bypass capacitor 574 and through a resistor 576 to the minus l4-volt supply. The output winding 578 of the step down transformer is employed to couple the signal from the unit 442 by way of a shielded cable 580 and through the capacitor 582 to the base of the transistor 530 in the unit 440.

The transistors 528 and 530 in the unit 440 act as a mixer or heterodyning circuit develop a beat frequency signal across the resistor 532 which has a frequency equal to the frequency difference between the signals developed by the oscillators 502 and 550. With this arrangement, the transistors 528 and S30 act as buffer stages for the respective oscillators to produce isolation between these oscillators so that they will not interact and cause pulling of one oscillator toward the other. This isolation is particularly important as the beat frequency signal approaches zero, since if one oscillator pulls the other into oscillation at the same frequency a false zero beat indication will be given and the coil 50 will be adjusted to the wrong inductance value.

The beat frequency signal is supplied by way of the conductor 584 to a low-pass filter circuit in the input of the unit 450. This low-pass filter passes signals up to approximately 6 megacycles and comprises the series inductive elements 586 and 588 and three shunt arms comprising an inductance 590 and capacitor 592, a capacitor 594,- and an inductance 596 and series capacitor 598. The beat frequency signal transmitted through this low-pass filter is supplied through the capacitor 600 to the base of a transistor 602 which acts as a wide band amplifier for the beat frequency signal. The collector of the transistor 602 is connected through a resistor 6.04 and compensating inductance 606 to ground. The emitter of the transistor 602 is connected through a capacitor 608 to ground and through a resistor 610 to a minus 20-volt supply point. The base of the transistor 602 is connected through a resistor 612 to the minus 20-volt supply point and through the resistor 614 to ground. An amplified beat frequency signal is developed at the collector of the transistor 602 and is transmitted through a capacitor 616 to the base of a transistor 618 which acts as a second stage of amplification and is connected in a similar fashion as the transistor 602.

The amplified beat frequency signal appearing at the collector of the transistor 618 is directly coupled to the base of an output transistor 620, the collector of which is connected to ground and the emitter of which is connected through a resistor 622 to the minus 20-volt supply. The transistor 620 feeds into a high pass filter indicated generally at 624. The filter unit 624 includes the series capacitors 626 and 628 and three shunt arms comprising an inductance 630 and series connected capacitor 632, an inductance 634 and an inductance 636 connected in series with a capacitor 638.

The amplified beat frequency signal passes through the high pass filter 624 so long as the beat frequency remains greater than 100 kilocycles, the cutoff frequency of the filter 624. Accordingly, at the start of the alignment cycle the beat frequency signal is passed through the filter 624 and is rectified in a rectifier 640 to provide a corresponding DC voltage across the rectifier load capacitor 642. This DC voltage is applied directly to the base of a transistor 644, the collector of which is connected to a minus l4-volt supply through a resistor 646 and the emitter of which is connected to ground through a resistor 648. The emitter of the resistor 648 is direct coupled to the base of a power transistor 650 which is arranged to energize the relay coil 452, described heretofore in connection with FIG. 18, and connected between the collector of the transistor 650 and the minus 24-volt supply.

As stated heretofore, the three coils on the unit 28 are preferably aligned simultaneously in the apparatus of FIGS. 1 to 11, inclusive. However, if the same zero beat or alignment frequency is used for all three coils, the oscillators associated with the coils and the oscillators associated with the reference tuning coil unit will interfere with one another and cause improper alignment of the respective coils. Accordingly, the oscillators 550 associated with the tuning coils 50a, 56a and 66a of the reference tuning coil unit are initially adjusted to operate at frequencies which are father apart than the pass band of the low-pass filter 587 in the input of each of the units 450. For example, if the filter 587 passes signals up to 6 megacycles the oscillators 550 may be adjusted to operate 10 megacycles apart so that signal interference from the different oscillators is avoided. Furthermore, if two of the coils on the unit 28, such as the RFoutput coil 56 and the mixer input coil 50, are mutually coupled, these coils are preferably aligned at frequencies spaced the farthest apart. For example, when a channel 2 tuning coil unit is being aligned the coil 56 may be aligned at a frequency of 30 megacycles, the coil 66, 64 at a frequency of 38 megacycles and the coil 50 at a frequency of 46 megacycles. For a channel 13 tuning coil unit, the coil 56 may be aligned at a frequency of 80 megacycles, the coil 66, 64 at a frequency of 90 megacycles, and the coil 50 at a frequency of 100 megacycles.

At the start of a particular alignment operation, the tuning coil 50a of the reference tuning coil unit, which has been precisely aligned to the desired channel, is initially placed in the apparatus so that it contacts the terminals 80, 82 and hence causes the oscillator in the unit 440 to oscillate. Assuming that the coil 50 is to be aligned at a frequency of I00 megacycles, a signal generator is connected to the cable 580, in place of the unit 442, and is set to supply a IOO-megacyele output signal to the mixer in the unit 440. A beat frequency signal is thus supplied to the unit 450 and an indicating device, such as a meter or amplifier and loudspeaker may be connected to the wide band amplifier at any suitable point, such as the emitter of the transistor 620. The capacitor 500 is then adjusted until a zero beat is obtained as indicated by the indicating device. The reference unit is then connected in the normal manner so that the coil 50a contacts the terminals 80a, 82a in the unit 442 and the signal generator is connected to the base of the transistor 528, through a suitable isolation circuit, to simulate an input from the oscillator 502. The signal generator output remains set at 100 megacycles and the capacitor 544 is now adjusted to give zero beat as determined by the indicating device connected to the emitter of the transistor 620. The capacitors 500 and 544 have thus both been adjusted to give identical oscillator frequencies with the inductance of the aligned coil 50a of the reference tuning coil unit. A similar initial adjustment is made for the alignment units associated with the probes 84 and 90. However, the signal generator would be set at a different frequency for each probe so that the coils may all be aligned simultaneously, as discussed above. In this connection it is pointed out that the units 440 for all three alignment probes are preferably positioned within the housing 368 is close to the contacts on the block 360, whereas the units 442 and 450 for all three probes may be located at any point at which the reference tuning coil unit may be conveniently inserted into and removed from the contacts 800, 82a, etc. of the units 442.

While there have been illustrated and described different embodiments of the present invention, it will be apparent that various changes and modifications thereof will occur to those skilled in the art. it is intended in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the present invention.

What I claim as new and desired to be secured by Letters Patent of the United States is:

l. A tuning coil unit for use in a turret tuner, comprising an elongated support member of insulating material, means defining a longitudinally extending recess in said support member, a plurality of conductive terminal members positioned at spaced points along the length of said support member, a plurality of coils wound around said support member, means connecting the ends of said coils to different ones of said terminal members, the portions of said coils which overlie said recess means being bent inwardly toward the center of said support member by amounts such that said coils have predetermined values of inductance.

2. A coil assembly for use in a turret-type tuner, comprising an elongated insulating supporting member, a plurality of conductive terminal members spaced along the length of said support member, a plurality of coils wound around said support member, each of said coil being positioned between a different pair of said conductive terminal members and having the ends thereof connected to adjacent terminal members of each pair, means defining a groove in said support member which extends beneath a portion of the turns of each of said coils, said turn portions being permanently deformed at least partially into said groove by amounts such that said coils have predetermined values of inductance.

3. A tuning coil assembly, comprising an elongated insulating support member, a pair of conductive terminal members spaced along the length of said support member, a coil wound around said support member and having the ends thereof connected to said terminal members, means defining recess means in said support member extending beneath at least a portion of said coil, the portions of said coils above said recess means being deformed inwardly into said recess means by an amount such that said coil has a predetermined value of inductance.

Claims (3)

1. A tuning coil unit for use in a turret tuner, comprising an elongated support member of insulating material, means defining a longitudinally extending recess in said support member, a plurality of conductive terminal members positioned at spaced points along the length of said support member, a plurality of coils wound around said support member, means connecting the ends of said coils to different ones of said terminal members, the portions of said coils which overlie said recess means being bent inwardly toward the center of said support member by amounts such that said coils have predetermined values of inductance.

2. A coil assembly for use in a turret-type tuner, comprising an elongated insulating supporting member, a plurality of conductive terminal members spaced along the length of said support member, a plurality of coils wound around said support member, each of said coil being positioned between a different pair of said conductive terminal members and having the ends thereof connected to adjacent terminal members of each pair, means defining a groove in said support member which extends beneath a portion of the turns of each of said coils, said turn portions being permanently deformed at least partially into said groove by amounts such that said coils have predetermined values of inductance.

3. A tuning coil assembly, comprising an elongated insulating support member, a pair of conductive terminal members spaced along the length of said support member, a coil wound around said support member and having the ends thereof connected to said terminal members, means defining recess means in said support member extending beneath at least a portion of said coil, the portions of said coils above said recess means being deformed inwardly into said recess means by an amount such that said coil has a predetermined value of inductance.

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