SIEMENS ELETTRA TV2357 CHASSIS INTERNAL VIEW.

This chassis of the SIEMENS ELETTRA TV2357 was first based on PCB circuit and adopting hybrid technology.

The chassis seems a TELEFUNKEN TYPE.

TELEFUNKEN TUBES TV CHASSIS
CIRCUITS DESCRIPTIONS OF TIMEBASE / DEFLECTIONS.

SIEMENS ELETTRA  TV2357 / TELEFUNKEN TUBES HORIZONTAL DEFLECTION CIRCUIT

The present invention relates to deflection circuits of the type employed for providing a time base in connection with cathode ray tubes for deflection of an electron beam.
Magnetic deflection systems are often employed in present day systems for deflecting an electron beam in a cathode ray tube. These magnetic deflection systems employ in general two coils arranged about the neck of the cathode ray tube and in which coils saw tooth wave forms of different frequencies are generated. In one arrangement for generating saw tooth current wave forms for line deflection of TV picture tubes and with which arrangement the present invention may be advantageously used, a condenser is provided which by means of a diode which is rendered conductive during the forward stroke of the saw tooth wave form, supplies a constant voltage to the winding of an auto transformer. By means of this constant voltage, a linearly increasing current is generated in the transformer and as a result also in the deflection coil coupled thereto. The loss of energy in the deflection circuit is corn-pensated during the forward stroke of the saw tooth wave form by the final sweep amplifier, which supplies such a current !that the diode conducts during the entire for-ward stroke of the saw tooth wave form. The diode is rendered non-conductive when current flow through the final sweep amplifier is cut-off by a saw tooth synchroniz-ing impulse fed to the control grid of the final sweep amplifier tube. In particular, the final sweep amplifier is cut-off by the negative flyback of a saw tooth synchronizing impulse fed to its control grid. When

the amplifier tube is cut off its anode voltage will rise, thus raising the voltage of the cathode of the diode beyond its anode voltage. The diode will therefore cease to conduct and the transformer as well as the deflecting coil and the stray capacities in. the circuit go through a free half cycle variation at the end of which, the voltage across the transformer is reversed and as a result the control diode again becomes conductive so that the above cycle may again be repeated. In addition, during the fly back period of the saw tooth synchronizing impulse, a high positive peaked voltage is developed across the transformer which is rectified by another diode. The rectified high peaked voltage is connected to the accelerat-ing anode of a cathode ray tube and serves to accelerate the electron beam in the cathode ray tube. A more detailed description of the above arrangement may be found in an article by R. Andrieu, titled, "The line deflection circuit with auto transformer" which ap-peared in a Telefunken paper, volume 95 in the year 1952. Accurate control of the sweep amplitude is an absolute requirement for line deflection circuits involving simul-taneous generation of high voltages for picture tubes. It is necessary in order to accurately control the line deflec-tion amplitude to compensate for variations in electrical value of deflection transformers, tubes, as well as for voltage source variations and the like.

The amount of deflection of the electron beam in a cathode ray tube depends not only on the amplitude of the saw tooth current wave form that flows through the deflection coil but also on the amplitude of the accelerate 5 ing voltage to which the electron beam is exposed. Since the saw tooth current wave form and the accelerating voltage are produced in the same circuit, it is obvious that an adjustment, of, for instance, the amplitude of the saw tooth current wave form will produce a con 10 comittant change in amplitude of the aLcelerating volt-age. The sweep amplitude is, on the one hand, directly proportional to the deflection current flowing through the deflection coil, and on the other hand, inversely propor-tional to the square root of the accelerating voltage. 15 It is often desired to regulate the sweep amplitude with-out affecting the focus of the electron beam on the screen of the image tube. This may be performed by ad-justing the sweep current amplitude while at the same time maintaining the high voltage, which is obtained dure 20 ing the fly back period, constant. On the other hand it may also be desired to adjust the focus of the electron beam on the screen of the picture tube. This focus adjustment may be performed by changing the magnetic field strength of a focussing magnet used with magnetical-25 ly focussed cathode ray tubes. If one, however, desires to employ a permanent magnet without additional focus-ing coils or without the necessity of adjusting the mag-netic field strength, the beam may be focussed by chang-ing the value of the accelerating voltage. However, as 30 already pointed out, a change in accelerating voltage will produce a change in the sweep amplitude, which is in-versely proportional to the square root of the accelerating voltage. Two ways are known for making the desired adjust-35 ment of the sweep amplitude. The first way concerns the adjustment of the fly back time, on which the magni-tude of the generated high voltage as well as the deflec-tion amplitude is dependent. The second way concerns the changing of the regulated anode voltage of the final 40 sweep amplifier tube in which case, the saw tooth ampli-tude will be directly proportional to the accelerating volt-age. In order to maintain a predetermined amplitude of the sweep, the saw tooth current must change as the square root of the accelerating voltage. With this rela-45 tionship of sweep current and accelerating voltage, a change in the size of the raster will result with changes in sweep amplitude. The adjustment of the anode voltage may be made, 'as known in the art, by means of a variable resistor con-50 nected in series with the anode supply voltage. The dis-advantage of adjusting the anode voltage with the above mentioned variable resistor lies in the fact that a certain amount of power will be dissipated by the resistor, thus requiring a higher initial anode supply If oltage. One of 55 the objects of the present 'invention is to provide a control arrangement for adjusting the anode voltage of the final sweep amplifier tube in such manner that additional power requirements are unnecessary. This is accomplished by making a variable c

onnection of the anode of the final 60 sweep amplifier tube with a transformer. A uniform. adjustment is made possible by coupling the final sweep amplifier tube parallel to a portion of the transformer winding by means of two series connected inductances. The anode of the final sweep amplifier tube is connected 65 to the junction of the inductances, while the free terminals of the inductances are connected across a portion of the transformer winding, at least one of the series connected inductances being variable. With this arrangement, the two inductances can be adjusted in such manner that the 70 'total inductance of the two series connected inductances always remains constant over the adjusting range. Where the total inductance of the series connected inductances

remains constant over the adjusting range, a change in Fig. 6 shows a modification of the circuit arrangement fly back time will occur with anode voltage adjustments of Fig. 1; inasmuch as the tube capacity is transformed at the de- Fig. 7 shows yet another modification of the circuit flection coil into a greater or smaller value with the ad- arrangement of Fig. 1; and justment of the adjustable inductances. 5 Fig. 8 shows yet other curves having characteristics dif-The adjusting arrangement may on the other hand be ferent from those illustrated in Figs. 3 and 4. _so designed that the total inductance of the series con- Fig. 1 shows one example of a circuit in accordance nected variable inductances instead of being held con- with the invention and serves for explaining the opera-stant, as described above, may be so dimensioned that the tion of the circuit in accordance with the invention. It total inductance value varies in the same sense, or direc- 10 is assumed that the condenser is charged ± and — as tion, as the inductance which has its free end terminal shown in Fig. 1. The diode 2, during the forward stroke _connected to the higher alternating voltage point on the of the synchronizing impulse supplied by the sweep gen-_transformer. In this case the fly back time will remain erator 5', connects a substantially constant voltage to the constant with an adjustment of the anode voltage so that transformer winding 3 which is illustrated as being an a sharp anode voltage adjustment can be made. 15 auto transformer. As a result of the constant voltage _ In order to obtain other arbitrary adjusting charac- connected to the transformer a linearly increasing cur-teristics, it is possible to connect, for instance, at least rent is generated in the transformer winding 3 as well as in one capacitor in parallel with at least one of the two the deflecting coil 4 which is coupled to the winding 3. series connected inductances. The loss of energy in the circuit is compensated during . From the above discussion it will be apparent that 20 the forward stroke of the synchronizing by the final sweep it is an object of the present invention to provide a beam amplifier 5. The amplifier 5 supplies such a current deflection circuit for cathode ray tubes in which the to the transformer that the diode tube 2 conducts during sweep amplitude and the high direct current voltage, the entire forward stroke of the synchronizing impulse. generated in the beam deflection circuit, may be inde- When the tube 5 is cut off by the negative fly back por-pendently adjusted. 25 tion of the synchronizing impuse which has an approxi-It is yet another object of the present invention to mately saw tooth wave form, the diode 2 will likewise be provide a beam deflection circuit for cathode ray tubes cut off. As a result the transformer 3 as well as the de-in which the sweep amplitude may be varied linearly with fleeting coil 4 and stray capacities in the circuit go through relation to the high direct current voltage. a free half cycle variation, at the end of which the volt-It is yet another object of the present invention to pro- 30 age across the transformer is reversed, and as a result the vide a beam deflection circuit for cathode ray tubes in control diode 2 is again permitted to conduct. The en-which the electron beam focus may be changed by ad- tire cycle is again repeated when the forward stroke of the justing the accelerating voltage without changing, when next syunchronizing impulse reaches the control grid 1' so desired, the sweep amplitude. of the final sweep amplifier tube 5. In addition, during Yet another object of the present invention is to pro- 35 The fly back period of the saw tooth synchronizing im-vide a beam deflecting circuit for cathode ray tubes in pulse, a high positive peaked voltage is developed across which the fly-back time may be accurately controlled. the transformer winding 6 which is rectified by diode 7. With the above objects in view the present invention The inductances 8 and 9 are connected in series, the mainly consists of a deflection circuit for generating in free terminals of the inductances 8 and 9, henceforth also an inductance a current having a saw tooth wave form 40 referred to as first and second inductances, respectively, and for simultaneously generating a high direct current being connected across another portion 12 of the trans-voltage, comprising, a condenser adapted to have a direct former 3. The first and second inductances are of the current voltage across its terminals, switching means con- type which may be adjusted in opposite direction so that nected in series with the condenser for applying the volt- the total inductance L8 plus L9 remains constant over the age across the terminals of the condenser to the induct- 45 entire adjusting range. This adjustment can be effected, ance when the switching means is actuated, a transformer for instance, by winding both coils on a common cylin-having a winding a first portion of which is coupled with drical coil form having an axial bore. Within the bore the inductance, an amplifier having an anode, the ampli- may be arranged a movable ferro-magnetic core. By fier controlling the operation of the switching means, and varying the position of the core in the coil form the in-a first and a second inductance connected in series to 50 ductance of one coil will increase while the inductance of form a junction to which the anode of the amplifier tube the other will decrease. is connected, the end terminals of the first and second Fig. 2 shows curves exemplifying the different voltage inductances being connected across a second portion of relationships between accelerating voltage and deflec-the transformer winding, at least one of-the inductances tion coil voltage that may be obtained for definite rela-being variable over a predetermined adjusting range. 55 tionships between the first and second inductances. Usp The novel features which are considered as charac- represents the voltage at the deflection coil 4 obtained teristic of the invention are set forth in particular in during the forward stroke of a saw tooth wave form, and the appended claims. The invention itself, however, both is plotted along the abscissa. Ux represents the high volt-as to its construction and its method of operation, together age generated at terminal H and is plotted along the ordi-with additional objects and advantages thereof, will be 60 nate axis. The high voltage when appropriately con-best understood from the following description of specific nected to a cathode ray tube serves to accelerate the elec-embodiments when read in connection with the accom- tron beam in the cathode ray tube. If the dimensions panying drawings, in which: of the adjustable inductances are chosen so that the Fig. 1 shows a circuit diagram of a deflection circuit in total inductance LB plus L9 is not maintained constant, but accordance with the present invention: 65 is instead varied in such manner that the total inductance Fig. 2 shows the various curves obtained by plotting varies in the same sense as does the inductance Ls so that the voltage at the deflection coil versus the accelerating the transformed tube capacity at the deflection coil 4 is voltage at terminal H in the circuit arrangement of Fig. 1; compensated, then the fly back time will remain constant Fig. 3 shows the curves obtained by plotting the varia- during the adjustment. Curve 21. shown in Fig. 2 shows tions in inductance versus core displacement of a control 70 the adjusting characteristic curve obtained with the last arrangement in accordance with the invention; mentioned relationship of the inductances L8 and Ls. Fig. 4 shows another set of curves having different char- The high voltage UH is seen to increase linearly with re-acteristics from those illustrated in Fig. 3; spect to the deflection amplitude. Curve 22 shows the - Fig. 5 shows schematically, a control arrangement used deflection amplitude Up as varying with the square root in a deflection circuit, in accordance with the invention; 75 of the high voltage UH. As may be noted from curve 22,

a change in accelerating voltages Uit produces substan- ductances. Ls and L9 were adjusted in opposite direction, tially no change of the deflection amplitude. If the total that- is as the inductance of one increased the inductance inductance change is more pronounced than that used for of the other decreased, by means of a common high fre-obtaining curve 21, then the fly back time will change quency core. An independent adjustment of high voltage when an adjustment of the sweep amplitude is made. 5 and deflection amplitude could also be obtained, however, Curve 21 can be transformed into curve 23 if so desired, by an arrangement wherein the two inductances are sep-in which case, an adjustment of the inductances will arated and form two mutually independent coils each of produce no change in the high voltage UH. The man- which is variable. In this case the oppositely directed ner in which this is accomplished will be explained here- adjustment of the first and second inductances is some-inafter. 10 what more difficult to perform since in, this case, the ad-Fig. 3 illustrates in curve form the variations of the in- justment of the two inductances must be simultaneously dividual coil inductances L8, L9 as well as the variation of made. This is however no limitation since the adjust total inductance, Ls, plus L9, with relation to core ment is not made very often during actual operation. displacement X, as obtained with the circuit arrange- Fig. 7 shows yet another embodiment of the present ment of Fig. 1. It is apparent from Fig. 3 that the 15

invention in which two condensers 10 and 11 are re-change in inductance value of the first and second in- spectively connected in parallel with the coils Ls and L. ductances are in opposite direction so that the total in- By assigning suitable values to the capacitors, these ductance as a function of core displacement, remains capacitors can be used to yield any desired variable ad-constant. justing curve so that in this case also the fly back time If desired, however, the inductances may also be so 20 can be controlled simultaneously with adjustments of related so that the total inductance, L8 plus L9, changes the control arrangement in accordance with the invention in the same sense as inductance L9, as shown in Fig. zia. in a desired manner. In this case the change in total inductance can be so For certain applications it may be desired to obtain selected that the change in transformed tube capacity at an adjustment of the deflection amplitude where the high nr the deflection coil 4 will be compensated, thereby main- voltage is held constant. In order to obtain such an ad-taining the fly back time constant when the adjustment is justment, the fly back must be changed while the ad-made. justment takes place. The arrangement heretofore de-The adjusment mentioned at last always gave an ad- scribed in which condensers 10 and 11 were respectively justment along a definite curve shown in Fig. 2, namely connected in parallel with the inductances Ls and L9 may curve 21, along which curve for each deflection coil volt- 30 be used for such purpose. age Usp there exists a corresponding definite high_ voltage As already noted it is also possible to adjust the hod-Urr. zontal sweep amplitude while holding the high voltage In accordance with another aspect of the invention both constant by means of an arrangement in which only in-mentioned magnitudes UH and Usp are adjusted independ; ductances are used as circuit elements. ently of one another. In this case the first and second 30 By increasing the coil spacing in an arrangement where inductances are arranged to be independently adjustable. the inductance values of the first and second inductances Such independent adjustments of the high voltage UH are changed in opposite directions as a function and of the deflection coil voltage Up may be effected with of core displacement as in Fig. 3, a curve of the in-the circuit arrangement illustrated in Fig. 1. To make ductance variations may be obtained such that the total such independent adjustments of the high voltage and the 40 inductance is considerably changed when making an ad-deflection coil voltage possible, the oppositely directed justment, which produces a considerable change in fly adjustments of the inductances Ls and L9 may be effected back time, while one of the inductances changes in value through the displacement of a high frequency core in the only slightly during the adjustment, as shown in Fig. 8. common coil axis, in which case, one of the two coils is Experiment has shown that it is possible with an ar-constructed as compared with the other, so that said one t.' rangement which exhibits the curves shown in Fig. 8 to coil may be spatially displaced along the coil form with hold, without any difficulty, the high voltage constant relation to the other. Fig. 5 shows an arrangement over an adjusting range of wherein one of the two coils may be displaced with rela- Another control arrangement in accordance with the tion to the other in accordance with the invention. Both invention, exhibiting an adjusting characteristic curve 50 coil sections L8 and L9 of the inductive voltage divider corresponding to that of Fig. 8 may be used, and which are arranged on a common coil form 31 and in such man- involves the connection of a fixed inductance of suitable ner that the coil, or inductance Ls, is rigidly secured to magnitude in parallel with the coil La. In Fig. 6 the the coil form 31 while the coil, or inductance, L8 is ar- parallel inductance is designated by reference numeral 13, ranged to be displaced in direction of the axis. Inside the 55 and shown therein as being adjustable, which together tubular coil form 31 is arranged a displaceable hi211 fre- e with coil 8 forms the inductance LEI In this case also, quency core 32 which serves to change the coil induc- the high voltage, when adjusting the inductances Ls, L92 tances Ls and L9 in opposite sense, that is, as one in- remains constant without having to make any adjust-creases, the other decreases. It is possible to obtain with ment of the inductance 13. As may be noted from Fig. 8 this arrangement, adjustments which will follow curves 60 the inductance L8 with displacements of the core is not 21, 22 or 23 of Fig. 2. It is also possible to obtain a high materially changed. voltage amplitude and a deflection amplitude of any value If the control arrangement in accordance with the ma with this control arrangement. As a iesult the need for vention employs an adjustable inductance L9 which is adjusting of focusing magnets to obtain a sharp beam connected in series with a fixed inductance Ls, then when focus is• overcome since a sharp focus setting may be 65 an adjustment is made, a change in deflection amplitude obtained with the control arrangement in accordance with may also be effected while simultaneously maintaining the invention by changing the high voltage level. the high voltage substantially constant. Fig. 6 shows another embodiment of the invention in The invention is not limited to the described embodi-which is connected in parallel with the inductance L8 an ments but may be used with deflection circuits which do independently adjustable inductance 13. The circuit 70 not involve the use of auto transformers but operate arrangement illustrated in Fig. 6 is similar to that of instead with any other type of standard transformer. Fig. 1 in all other respects. The inductance 13 makes it It will be understood that each of the elements de-possible to adjust the horizontal sweep amplitude while scribed above, or two or more together, may also find a the high: voltage is maintained at a constant level. useful application in other types of deflection circuits in all of the arrangements described up to now the in- 75 differing from the types described above.

While the invention has been illustrated and described 'as embodied in magnetic deflection circuits, it is not in--tended to be limited to the details shown, since various 'modifications and structural changes may be made with-out departing in any way from the spirit of the present invention. . Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for vari-ous applications without omitting features that, from the standpoint of prior art, fairly constitute essential charac-leristics of the generic or specific aspects of this inven-tion and, therefore, such adaptations should and are in-tended to be comprehended within the meaning and range of equivalence of the following claims. 7_ What is claimed as new and desired to be secured by Letters Patent is: 1 1. A deflection circuit for generating in an inductance _a current having a sawtooth wave form and for simul- taneously generating a high direct current voltage, corn- , . -prising in combination, a condenser adapted to have a rdirect current voltage across its terminals; switching means connected in series with said condenser for ap-plying said voltage across said terminals of said con-'denser to the inductance when said switching means is -actuated; a transformer having a winding a first portion of which is coupled with the inductance; an amplifier having an anode, said amplifier controlling the operation of said switching means; and a first and a second in-ductance connected in series to form a junction to which -said anode of said amplifier tube is connected, the end terminals of said first and second inductances being con-nected across a second portion of said transformer wind-ing, at least one of said first and second inductances _being variable over a predetermined adjusting range. 2. A deflection circuit for generating in a first in--ductance a current having a saw tooth wave form and for simultaneously generating a high direct current voltage, comprising in combination, a condenser adapted to have a direct current voltage across its terminals; switching means connected in series with said condenser for ap-plying said voltage across said terminals of said con-denser to the first inductance when said switching means is actuated; a transformer having a winding a first por-tion of which is coupled with the first inductance; an amplifier tube having an anode and controlling the opera-tion of said switching means; and a pair of adjustable inductances connected in series to form a junction to which said anode of said amplifier tube is connected, the end terminals of said pair of inductances being con-nected across a second portion of said transformer wind-ing, said pair of inductances being arranged with respect -to each other to be simultaneously adjustable in op-posite directions so as to yield a total inductance which is constant over the entire adjusting range. 3. A deflection circuit for generating in an inductance a current having a sawtooth wave form and for simul-taneously generating a high direct current voltage, com-prising a combination, a condenser adapted to have a di-rect current voltage across its terminals; switching means connected in series with said condenser for applying said voltage across said terminals of said condenser to the inductance when said switching means is actuated; a trans-former having a winding a first portion of which is coupled with the inductance; an amplifier having an anode, said amplifier controlling the operation of said switching means; a first and a second inductance connected in series to form a junction to which said anode of said amplifier tube is connected, the end terminals of said first and second inductances being connected across a second por-tion of said transformer winding, at least one of said first and second inductances being variable over a pre-determined adjusting range; and at least one condenser

connected across at least one of said inductances for se-lecting a desired adjusting curve. 4. A deflection circuit for generating in an inductance a current having a saw tooth wave form and for simul-taneously generating a high direct current voltage, comprising in combination, a condenser adapted to have a direct current voltage across its terminals; switching means connected in series with said condenser for applying said voltage across said terminals of said condenser to the inductance when said switching means is actuated; a transformer having a winding a first portion of which is coupled with the inductance; an amplifier having an anode, said amplifier controlling the operation of said switching means; a first and a second inductance connected in series to form a junction to which said anode of said amplifier tube is connected, the end terminals of said first and second inductances being connected across a second por-tion of said transformer winding, at least one of said first and second inductances being variable over a predeter-mined adjusting range; and a third adjustable inductance connected in parallel with one of said first and second inductances. 5. A deflection circuit for generating in a first induc-tance a current having a saw tooth wave form and for simultaneously generating a high direct current voltage, comprising in combination, a condenser adapted to have a direct current voltage across its terminals; switching means connected in series with said condenser for apply-ing said voltage across said terminals of said condenser to the first inductance when said switching means is actuated; a transformer having a winding a first portion of which is coupled with the first inductance; an amplifier tube hay-ing an anode and controlling the operation of said switch-ing means; and a pair of adjustable inductances connected in series to form a junction to which said anode of said amplifier tube is connected, the end terminals of said pair of inductances being connected across a second portion of said transformer winding, said pair of inductances being arranged with respect to each other to be simul-taneously adjustable in opposite directions so as to yield a total inductance which is constant over the entire ad-justing range, said pair of inductances forming control means for changing the amplitude of the sawtooth wave form while the high direct current voltage remains sub-stantially constant. 6. A deflection circuit for cathode ray tubes employing electro-magnetic deflecting coils comprising, in combina-tion, an output transfoi mer, the electro-magnetic deflect-ing coils being coupled to a first portion of said output transformer; a switching diode; a boost condenser, said diode and said condenser being connected in series across a second portion of said output transformer to develop across said boost condenser a voltage representative of recovered energy cyclically stored in the deflection cir-cuit; a deflection output tube having at least an anode and a cathode; a first and a second inductance connected in series to form a junction, the end terminals of said first and second inductances being connected across a third portion of said output transformer, the junction of said first and second inductances being connected to the anode of said deflection output tube, said inductances having windings adapted to be wound about a tubular coil form; and a high frequency core adapted to be slidably mounted inside the tubular coil form to change the in-ductance values of said two inductances in opposite di-rections. 7. A deflection circuit for cathode ray tubes employ-ing electromagnetic deflecting coils comprising, in com-bination, an output transformer; a deflection output tube, having at least an anode and a cathode, the electromag-netic deflecting coils being coupled to the anode-cathode circuit of said output tube through said output transform-er; a switching diode; a boost condenser, said diode and said condenser being connected in series across a first


portion of said output transformer to develop across said boost condenser a voltage representative of recovered energy cyclically stored in the deflection circuit; and means for adjusting the amplitude of the deflection volt-age for the cathode ray tubes, said means including a 5 pair of inductances connected in series across a second portion of said output transformer and having a junction point, the anode of said deflection output tube being con-nected to said junction point, at least one of said series con-nected inductances being adjustable to provide a variable 10 coupling between said output tube and said output trans-former. 8. A deflection circuit for cathode ray tubes employing electro-magnetic deflecting coils comprising, in combina-tion, an output transformer, the electromagnetic deflecting 15 coils being coupled to a first portion of said output trans-former; a switching diode; a boost condenser, said diode and said condenser being connected in series across a second portion of said output transformer to develop across said boost condenser a voltage representative of 20 recovered energy cyclically stored in the deflection circuit; a deflection output tube having at least an anode and a cathode; a first and a second inductance connected in series to form a junction, the end terminals of said first and second inductances being connected across a third por-ton of said output transformer, the junction of said first and second inductances being connected to the anode of said deflection output tube; means for adjusting at least one of said first and said second inductances to vary the inductance thereof through a predetermined range; and a first and second condenser connected respectively across
said first and second inductances for selecting a desired inductance adjusting curve. 9. A deflection circuit for cathode ray tubes employing electromagnetic deflecting coils comprising, in combina-tion, an output transformer; a deflection output tube, having at least an anode and a cathode, the electromag-netic deflecting coils being coupled to the anode-cathode circuit of said output tube thrcugh said output transformer; a switching diode; a boost condenser, said diode and said condenser being connected in series across a first por-tion of said output transformer to develop across said boost condenser a voltage representative of recovered energy cyclically stored in the deflection circuit; rectifier means connected to a winding of said output transformer to derive a high voltage from voltage pulses cyclically arising in said output transformer; and means for adjust-ing the amplitude of the deflection voltage for the cath-ode ray tubes, said means including a pair of inductances connected in series across a third portion of said output transformer and having a junction point, the anode of said deflection output tube being connected to said junc-tion point, said pair of inductances being simultaneously adjustable in opposite directions to give a total inductance which is constant over the entire adjusting range.

TELEFUNKEN TUBES TV Vertical deflection television circuit:

The present invention relates generally to circuits for
cathode ray tubes which generate saw tooth current curves,
and especially for the vertical deflection of one or several
electron beams in the picture tube of a television receiver,
wherein during the forward cource of the saw tooth curve
the ohmic voltage is high compared to the inductive volt‑
age.
In some cathode ray tube (CRT) circuits, the deflecting
coils at the line frequency, during the forward deflection
of the saw tooth deflecting current, are mostly inductive.
This is not true for the lower frequencies of vertical de‑
flection. In the latter case, the deflecting coils provide a
substantially ohmic resistance having but a small inductive
component. However this is not always true with the more
rapid fly-back pulse.
To produce a linear increase of the coil current during
forward deflection, a linear increase of the coil voltage
is also necessary. This increase is provided by a tube
either coupled directly I to the coil or through a trans‑
former. The control voltage is produced by an RC-circuit
which discharges through a tube, such as a blocldng oscil‑
lator. When using transformer coupling, it is usual to
employed relatively small transformers, for reasons of
economy, and because of this the deflecting current curve
in the coils deviates considerably from a saw tooth curve.
It is known that in order to achieve a linear rising flank
Of the saw tooth current curve, it is advantageous to pro‑
vide the charging capacitor with a frequency dependent
negativeS feedback from the transformer or from the anode
circuit of the tube. Such a negative feedback has been 40
provided in known circuits by means of a capacitive volt‑
age divider connected between the transformer, or anode,
and the charging capacitor. The tapping point of this volt‑
age divider is connected to a point of substantially axed
voltage through one or several resistors. By a substantial- 45
ly fixed voltage, is meant a voltage which has only slight
fluctuations with respect to the voltage which has only
slight fluctuations with respect to the voltage on the other
side of the resistance. The capacitive voltage divider is ,n
so designed that the first • capacitor in the negative feed-
back path, together with the resistance connected in the
shunt path forms a differentiating section which reduces
the negative feedback for the lower frequencies. By this
means the defects and deviations from a saw tooth curve r„
brought about by the finite inductance of the transformer,
are corrected. The remainder of the capacitive voltage
divider forms an integrating section which renders the neg‑
afive feedback voltage proportional to the current flowing
in the deflecting coils and filters out the fly-back peaks.
When using a CRT having a radius of screen curvature 60
which is greater than the distance from the screen to the
center of deflection of the vertical deflecting coils, there
is tangent error (flat screen) distortion. To obviate this
distortion the deflecting current is rendered S-shaped, by
altering the shape of the curve of the control grid voltage 65
of the tube in whose anode circuit the coil is situated,
while the effective voltage of the charging circuit is altered.
The S-shape distortion of the control voltage curve has

also been provided in the past by connecting the remote
end of the charging resistor with respect to the capacitor
through an integrating circuit with the anode of the con‑
trolled tube. The time constant of this circuit is at least
double the duration of the period of one scanning.
However, with this circuit it is not possible to compen‑
sate for the tangent error while operating the transformer
at optimum conditions. The tangent error distortion could
be compensated for in the lower half of the picture by pro‑
viding a lesser preliminary correctiOn of the distortion of
the control voltage and compensating for the expansion
thus caused in the upper half of the picture through the
adjustable integrating section. However, the region of the
picture affected by this section amounts to only a few
lines at the upper border }of the picture and this method
is therefore not useful for correction of the tangent error
distortion.
With these defects of the prior art in mind, it WI main
object of this invention to provide a circuit for elitninating
tangent error distortion.
Another object is to provide such a circuit wherein
there is predistortion of the control potential to aid in cor‑
reeling tangent error distortion and which may be adjusted
to be a minimum or even eliminated.
These objects and others ancillary thereto are accom‑
plished according to preferred embodiments of the inven‑
tion, wherein a circuit is provided for eliminating tangent
error distortion and rendering the rising flank of the saw
tooth curve linear. The circuit includes a frequency de‑
pendent negative feedback section coupled to a capacitive
voltage divider. A linearity regulator is connected between
the tapping point of the capacitive voltage divider and a
substantially fixed voltage for correcting the tangent error
distortion, and is connected as well with one or more cirs
cult elements, providing an additional predistortion of the
control voltage. This is done in such a manner that when
the linearity regulator is short-circuited this predistortion
is disconnected or at a minimum.
In a preferred embodiment an additional resistance is
connected between the anode of the tube feeding the coils
and a tapping point of a first resistance connected between
the capacitive voltage divider and the point having a sub‑
stantially constant voltage. The first resistance is variable
so that the balance between the linearity in the lower and
upper halves of the picture and the compensation for the
tangent error distortion may be adjusted. Thus, an un‑
distorted portion of the anode AC. voltage of the tube
is applied to the tapping point of the voltage divider, i.e.,
the integrating section. This portion of the A.C. voltage
reduces the frequency dependent negative feedback in the
latter portion of the curve corresponding to the lower
border of the picture, and increases this feedback in the
first portion of the forward deflection of the saw tooth
curve. When the regulator is short-circuited the undis‑
torted portion for the negative feedback is zero.
Additional objects and advantages of the present in‑
vention will become apparent upon consideration of the
following description when taken in conjunction with the
accompanying drawings in which:
FIGURE 1 is a circuit diagram of the vertical deftec:•
lion circuit comprising the present invention.
FIGURE 2 are curves provided by various sections of
the circuit of FIGURE 1 and which are labeled a, b, c,
and d.
FIGURE 3 is a circuit diagram of a vertical deflection
circuit which has actually been constructed and used.
FIGURE 4 is a circuit diagram of another embodi‑
ment of the invention.

FIGURE 5 is a circuit diagram of a further embodi- rection of the tangent error distortion. Inasmuch as the ment. regulator 12 acts as a balancing regulator, the intensified FIGURE 6 is a circuit diagram of still another embodi- differentiation produced for the upper half of the picture ment. at the same time influences the lower half of the picture. With more particular reference to the drawings, FIG- 5 In known circuits, which do not use resistor 15, such a URE 1 illustrates a theoretical vertical deflection circuit selection of the differentiating section would manifest it-wherein the deflecting coils 1 are connected through a self as a marked expansion of the lower half of the 'picture. transformer 2 with the anode 40 of an amplifying tube 3. However, with the use of resistor 15, an additional Ire-The anode 40 is connected with the operating voltage quency dependent negative feedback is introduced which + VB through the primary winding 4 of transformer 2. 10 has a greater effect in the upper half of the picture than A control voltage having a saw tooth shaped curve is fed in the lower half of the picture. This is so because the from a charging capacitor 5 through :a coupling capacitor anode A.C. voltage is greater. 6 to the control grid of the amplifier tube. This voltage When regulator 12 is short-circuited, the greatest effect is obtained from RC-circuit 7, 5 whereby capacitor 5 is is obtained from the differentiating section 9, 11, 12 and charged through resistor 7 and discharged through block- 15 the cutoff frequency is at its highest. Also, the crowding ing oscillator 3. of the lines at the beginning of the picture and the ex-A negative feedback section or channel is connected pansion of the lines at the end of the picture are the between anode 40 and control grid 41 of tube 3 for render- greatest. The above-mentioned portion of the undis-ing linear the current which flows through deflecting coils torted anode A.C. voltage is zero. If the value of re-1 and which has a saw tooth shaped curve. 20 sistance 12 is increased, the differentiation action is This feedback section comprises a capacitive voltage lessened and the expansion of the lines is uniformly re-divider including capacitors 9, 10, and two resistors 11, 12 duced. Also the undistorted portion of the anode AC. connected between the point c, which is the junction of voltage at point 14 becomes noticeable and this primarily capacitors 9 and 10 and ground. Resistor 12 is variable. has a delaying effect on the upper half of the picture. Furthermore, a variable resistor 13 is connected between 25 Curve d of FIGURE 2 shows the control grid voltage of the capacitor 10 and coupling capacitor 6 or charging tube 3. capacitor 5. A resistor 15 is connected between junction FIGURE 3 illustrates a circuit constructed in accord-noint 14 of resistors 11, 12 and anode 40 or point b ance with the present invention which has actually been of the negative feedback channel to attenuate the voltage constructed and used. The values of the various corn-in differentiating sections 9, 11 and superposes an undis- 30 ponents are indicated in the drawing. torted portion of the voltage, having a saw tooth curve, FIGURE 4 illustrates a further embodiment of the from the tube 3 on point c. Junction point 14 may be invention wherein corresponding elements are identified connected with junction point 18 of capacitor 10 and with the same reference numerals used in connection with. resistor 13 through capacitor 16 and resistor 17. A grid FIGURE 1. In this embodiment the linearity regulator leak resistor 19 is provided for tube 3. Resistor 21 and 35 is provided in the shunt branch of the capacitive volt-capacitor 20 form the RC-section for the cathode circuit age dividers 9, 10. This is accomplished by connecting of tube 3. One terminal of the charging capacitor is a resistor 25 in parallel with a series circuit including a connected to the junction of the RC-section 20, 21, with variable resistor 26 and a resistor 27. The tapping point the cathode 42 of the tube 3. 28 of this series circuit located between resistors 26 and The operation of this circuit will now be explained 40 27 is connected with anode 40 through capacitor 29. W with reference to the curves of FIGURE 2. To eliminate When regulator 26 is short-circuited, capacitors 9 and tangent error distortion, the voltage at charging capacitor 29 are connected in parallel. In this case the resistors 5, which is rising according to an e-function, is distorted 25 and 27 are also connected in parallel and the differ- by a frequency dependent negative feedback to such an 45 entiating section has its highest cutoff frequency. When extent that the saw tooth curve of the current in the coils resistor 26 is increased the total resistance in the shunt considered from the center of the picture becomes con- branch increases and capacitor 29 has less effect so that tinuously decreased relative to the linear course. An S- the cutoff frequency continuously becomes lower. This shaped component is superimposed on the linear portion occurs because the total resistance is increasing faster of the curve. The curve of the voltage due to the nega- than the capacitance is decreasing. By this means, the tive feedback at charging capacitor 5 is illustrated by lines in the lower half of the picture are crowded together curve a of FIGURE 2. The curve of the anode A.C. more than the lines in the upper half of the picture are voltage of tube 3 at point b is illustrated in curve b. This expanded, and, considering the entire picture, the middle voltage is differentiated by RC-section 9, 11, 12, so that is expanded and the upper and lower halves are corn- 55 the low frequencies in the negative feedback section be- pressed. come ineffective, i.e., attenuated. In selecting values of resistors 25, 26, and 27, resistor By means of integrating sections 13, 6, 5, the fly-back 25 must be large with respect to resistor 27, and the pulse, such as 22 in curve c, FIGURE 2, is filtered out parallel circuit including these resistors should be about and the negative feedback voltage fed to the control 100,000 ohms, while the parallel circuit including capaci- grid 41 is rendered approximately proportional to the cur- nr, tors 9 and 29 should be about 33 nanofarads (1 nanofarad tiU rent in the deflection coils. Furthermore, the anode A.C. equals 10-9 farads). voltage passes through resistor 15 to tapping point 14 FIGURE 5 illustrates another embodiment of the in- of voltage divider 11, 12. Thus, the resistors 12, 15 serve vention wherein the linearity regulator 12 is mechanically as a voltage divider for the undistorted anode AC. voltage coupled with a variable resistor 30 which together with resistor 19' forms the grid leak resistance 19. Thus, the and they determine the value of the portion of this voltage "r, r linearity of the control voltage fed to the control grid fed to tapping point c. The voltage curve at point c is shown in curve c of FIGURE 2. The dashed line shows of tube 3 may be varied in accordance with the position of the linearity regulator. the curve after resistor 15 has been inserted into the FIGURE 6 illustrates a further embodiment wherein circuit. on the tap of the ohmic voltage divider connected in the The greater steepness in the first portion of the fore 70 shunt circuit of the capacitive voltage divider, a grid leak ward deflection is a result of both the portion of the resistance 19 is connected. Grid leak resistance 19 in- anode A.C. voltage as well as the increased differentiation eludes a potentiometer 31 directly connected to the tap, action of section 9, 11, 12. This is required to attain a as well as a resistor 19'. The movable contact of this gradually decreasing crowding of the lines from the start potentiometer is connected with the substantially constant to the middle of the picture and this is desired for cor- 75 voltage which is ground.

In the circuits of FIGURES 5 and • 6 resistor 15 of FIGURE 1 may be inserted if desired. It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of equiva-lents of the appended claims. What is claimed is: • A circuit arrangement for producing a current having a saw tooth shaped curve for the deflection of an electron beam of a CRT wherein theI radius of curvature of the screen is greater than its distance from the center of deflection, comprising an output circuit having deflecting coils presenting an ohmic load with an inductive comp-nent for the saw tooth current, tube means connected to said output circuit and having an anode and a control grid for generating a saw tooth control voltage; capacitive voltage divider means including two capacitors connected to the tube anode for predistorting the saw tooth control voltage with frequency dependent negative feedback which is fed to the control grid; a variable linearity regulator having a tapping point and connected to a tapping point of the capacitive voltage divider between the two capaci-• tors and a substantially fixed voltage for correcting the tangential 'distortion; and at least one circuit element means connected with said regulator to bring about an additional predistortion of the control voltage so that when the linearity regulator is short-circuited the addi-tional predistortion is minimal. 2. A circuit arrangement according to claim 1, com-prising an ohmic resistance connected between said tube anode and the tapping point of the linearity regulator. 311 A circuit arrangement according to claim 1, compris-ing a resistance forming a shunt branch with respect to the capacitive voltage divider; a series circuit including• a variable and a fixed resistance connected in parallel with the shunt branch resistance; and a capacitor con-nected between the tapping point of said series circuit and the tube anode. 4. A circuit arrangement according to claim 1, corn-prising a resistance forming a shunt branch with respect to the capacitive voltage divider; a grid leak resistance including a fixed and a variable resistor, connected_ to the shunt branch resistance, a movable contact of said variable resistor being connected to ground. 5. A circuit arrangement according to claim 1, corn-prising a variable grid leak resistor connected between ground and the control grid, said linearity regulator be-ing mechanically coupled to the grid leak resistor for simultaneous adjustment. •6. A circuit arrangement for producing a current having a saw tooth shaped curve for the deflection of an electron beam of a CRT wherein the radius of curvature of the screen is greater than its distance from the center of deflection, comprising an output circuit having deflecting coils presenting an ohmic load with an inductive compo-nent for the saw tooth current, tube means connected to said output circuit and having an anode and a control grid for generating a saw tooth control voltage; capacitive voltage divider means including two capacitors connected to the tube anode for predistorting the saw tooth control voltage with frequency dependent negative feedback which is fed to the control grid; a variable linearity regulator having a tapping point and connected to a tapping point of the capacitive voltage divider between the two capaci-tors and a substantially fixed voltage for correcting the tangential distortion; and at least one circuit element means connected with said regulator to bring about an additional predistortion of the control voltage so that when the linearity regulator is short-circuited the addi-tional predistortion is eliminated. 7. In a circuit arrangement using a tube for producing a saw tooth shaped current curve for the magnetic deflec-tion of one or several electron beams of a CRT, in which

the radius of curvature of the picture screen is greater than its distance from the center of deflection, the output circuit including deflecting coils which present an ohmic load with an inductive component for the saw tooth cur-5 rent, and to the control grid of which is fed a saw tooth shaped control voltage, obtained through a periodic charge and discharge of a capacitor, predistorted through a frequency dependent negative feedback by means of a capacitive voltage divider, the improvement comprising 10 a linearity regulator inserted between the tapping point of the capacitive voltage divider and a substantially fixed potential for correction of the tangential distortion, said linearity regulator being connected with at least one circuit element means bringing about an additional predistortion 15 of the control voltage in such a manner that when the linearity regulator is shortcircuited, the additional pre-distortion is minimal or is cut off. 8. A circuit arrangement according to claim 7, comprising a resistance connected as a shunt branch to the capaci-tive potential divider, the series connection of an adjust-able and fixed resistance being connected in parallel with said shunt branch resistance, the tapping point of the series connection being connected over a capacitor with the anode of the tube. 25 9. In a circuit arrangement for producing a current having a saw tooth shaped curve for the deflection of an electron beam of a CRT wherein the radius of curvature of the screen is greater than its distance from the center of deflection, and including tube means having an anode 30 and a control grid, an output stage for the tube means having deflecting coils presenting an ohmic load with an inductive component for the saw tooth current, load capacitor means connected to be periodically charged and discharged to apply to the control grid of the tube means 35 a voltage having a saw tooth shaped curve, feedback means connected between the tube means anode and the tube means control grid for applying a frequency depend-ent negative feedback to the control grid for predistorting the saw tooth shaped control voltage and including two 40 series connected capacitors, and a linearity regulator in-cluding a variable resistor connected from the connection point between the capacitors to a point of substantially fixed potential, the improvement comprising means con-nected to the tube anode and to the linearity regulator 45 for applying a voltage from the anode to the linearity regulator in a substantially undistorted manner to provide an additional predistortion of the control voltage effective at the control grid of the tube for eliminating the tangen-tial error, which voltage exceeds the amount to be used 50 for linearizing the deflection current, said regulator hav-ing a short circuited position in which said anode voltage is substantially zero. 10. In a circuit arrangement for producing a current having a saw tooth shaped curve for the deflection of an 55 electron beam of a CRT wherein the radius of curvature of the screen is greater than its distance from the center of deflection, and including tube means having an anode and a control grid, an output stage for the tube means having deflecting coils presenting an ohmic load with an 60 inductive component for the saw tooth current, load capacitor means connected to be periodically charged and discharged to apply to the control grid of the tube means a voltage having a saw tooth shaped curve, feedback means connected between the tube means anode and the 65 tube means control grid for applying a frequency depend-ent negative feedback to the control grid for predistorting the saw tooth shaped control voltage and including two series connected capacitors, and a linearity regulator in-eluding a variable resistor connected from the connection 70 point between the capacitors to a point of substantially fixed potential, the improvement comprising coupling means for connecting the load capacitor to the tube means for providing an additional predistortion of the control voltage effective at the control grid of the tube means 75 for eliminating the tangential error, which voltage exceeds
the amount to be used for linearizing the deflection cur-rent, said coupling means being variable to vary the time constant thereof independently of the effect of negative feedback, said regulator having a short circuited position in which the additional predistortion of the control voltage is substantially zero.
TELEFUNKEN EHT High voltage transformer

The present invention relates to a high voltage
transformer, particularly, for television receivers adapted to
produce high voltage peaks from the horizontal sweep or
flyback, these transformers having a rectangular, closed
iron core and a clindrical winding form mounted on
one of the legs of the core.

It has been known in such horizontal sweep transformers
to wind a high voltage winding having a narrow
width and a correspo ndingly increased height, in order to
avoid corona effects and arcing-over to the low voltage
windings, whereby the outmost winding layers, where the
highest voltage pulses occur, have been

spaced from the
other layers by a distance as large as possible.

Furthermore, it has been known to improve the insulation of
the ends of the transformer windings by providing soldering
terminals on a lateral flange of the winding form,
said flange having an enlarged diameter and being pro
vided with several reenforcing ribs.

In fastening the high voltage winding on the low voltage winding,
wedge means have been used for obtaining
a secure support. This has-the disadvantage that, particularly
in case of transformers in which a radial spacing
between the low voltage winding and the high voltage
winding is provided, the low voltage winding may be
damaged. This radial distance may be filled by a ring of
synthetic or plastic material.

It is an object of the present invention to avoid the
foregoing disadvantages by mounting the winding form
of the separately wound high voltage winding on the
winding form supporting the low voltage winding.
Still further objects and the entire scope of applicability of
the present invention will become apparent from
the detailed description given hereinafter; it should be
understood, however, that the detailed description and
specific examples, while indicating preferred embodiments
of the invention, are given by way of illustration only,
since various changes and modifications within the spirit
and scope of the invention will become apparent to those
skilled in the art from this detailed description.

In the drawings: :
Figure 1 shows a side view partially in section of a prior
art high voltage transformer for a television receiver, the
lower part of the core being omitted;

Figures 2 to 4 show similar side views partially in sections
of embodiments of high voltage transformers
according to the present invention. Like parts in these
figures are designated by the same reference numerals as
in Figure 1.

Figures 5 and 6 show views of the winding form in
perspective according to Figs. 2 and 3.Fig. 7 is an exploded view in perspective of the
elements of the transformer according to Figure 3.
In the prior art high voltage transformers of Figure 1,
a rectangular, closed iron corevl is formed of two
Ushaped parts. A winding form 2, suitably made of
synthetic or plastic material, supporting a low voltage
winding 3 is provided on one of the core legs, one of the ends
of this winding form 2 having a flange 4 of large
diameter carrying a number of soldering terminals 5. The low
voltage winding 3 is first wound on the form 2 covering
a relatively large width. A ring 6 of synthetic or plastic
i material is then mounted at the center of the winding 3
as a form to support a narrow high voltage winding 7 in
order to obtain a large magnetic leakage. The
circumference of the high voltage winding 7 is protected against
corona effects by a bead 8 of sealing compound or the
I like, such corona effects readily occurring at the outer
periphery, due to the high field intensities. The cross
section of the core leg is circular within the form 2 in
order to obtain better coupling, said cross section being
approximately the same as that of the inner diameter ofF
the form 2. The flange 4 of the form 2 is provided with
a cut-out near reference character 9, intended to
accommodate the leg of the core which is adjacent to the
core leg carrying the windings. The flange 4 is provided
with reenforcing ribs 10, between each of which one end
of a winding 11 is passed to the respective soldering
terminal. This known construction has the disadvantage
that the ring 6 of synthetic or plastic material has to be
wedged on the low voltage winding 3 to secure it in place.
In the high voltage transformer shown in the
embodiment of Figure 2, the high voltage winding 7 is
mounted on a separate cylindrical form 12 rather than on
the ring 6 of synthetic material as in Figure 1, recesses 13
being provided in the reenforcing ribs 10 for centering
the form 12 adjacent the flange 4. The one end of the
cylindrical form 12 is mounted in these recesses 13. As
a result of this construction, the low voltage winding is
protected against mechanical damage and, in addition to
this, a higher protection against arc-overs is obtained.
According to the embodiment of the invention shown
in Figure 3, a ring 14 of synthetic or plastic material is
provided as a support for the high voltage winding 7 in
a similar manner as in Figure 1. However, in contrast
to the transformer in Figure 1, the inner diameter of the
supporting ring 14 is larger than the outer diameter of
the low voltage winding 3. This supporting ring 14 of
insulating material is mounted by means of a plurality of
pins 15 which, at one of their ends, are fastened to the
supporting ring 14 and are inserted at their other ends
in holes 16 suitably provided in the flange 4 of the form 6
2, when the transformer parts are assembled.
Finally, in the embodimentof the high voltage trans-
former of Figure 4, a cylinder 17 inwardly flanged at one
of its ends is provided as a form for supporting the high
voltage winding 7. An opening 18 is provided through
the flanged end of this cylindrical form 17, the diameter
of this opening 18 being the same as the outer diameter
of the form 2, whereby the cylinder 17 may be placed
o'ver said form 2 during assembly. The tolerance of the
opening is selected in such a manner that a press-fit of
the form 17 _on the form 2 is assured.



1. A high voltage transformer comprising, a core; a
first coil form having an opening therethrough to receive
said core; a low voltage winding on said first form and
said winding being long in the axial direction as
compared with its height on the first coil form; a second coil
form having an opening therethrough of greater diameter
than the outer diameter of said low voltage winding; a
high voltage winding on said second coil form and said
high voltage winding being short in the axial direction as
compared with its height on the second form, said second
form being disposed in spaced relation over said low
voltage winding and being attached to and supported on a
portion of said first form at locations offset from the ends
of said windings, said second form comprising a cylinder
having an inwardly disposed flange at one end, the inner
periphery of the flange being complementary in shape
with the outer periphery of the first form and being. a
pressfit thereover.

2. A. high voltage transformer comprising, a core a
first coil term having an opening therethrough to receive
said core; a low voltage winding on, said first form and
said winding being long in the axial direction as compared
with its height on the first coil form; a second coil form
having an opening therethrough of greater diameter than
the outer diameter of said low voltage winding; a high
voltage winding on said second coil. form and said high
voltage winding being short in the axial direction as
compared with its height on the second form, said second
form being disposed in spaced relation over said low
voltage winding and being attached to and supported on
ia portion of said first form at locationsuofiset from the
ends of sa

id windings, said portion of said first form
comprising an outwardly disposed flange or set from one
end or the low voltage winding and having an annular
series of holes, the axes of which are parallel with the
axis of the low voltage wiNding, and said second form
comprising a ring coaxial with said low,voltage winding
and having an annular series of holes opposite and aligned
with the holes of the first mentioned series; and a
support pin transfixing the ring and the flange. through each
pair of aligned hole


Tuning is obtained with rotatable drum selectors for VHF and variable rotatable capacitor for UHF.
A rotatable drum containing twelve pre-defined channel-specific filters determines the received channel, where the inductors of the input matching, the channel filter and the LO tank circuit are changed. The tuner is divided into two chambers for maximum isolation between the sensitive RF input and the mixer-oscillator-IF section with its much larger signals. Also on the drum there are eventually two separate sub-modules.
It's completely based on tubes technology.
With this concept, which essentially turned the tuner module into a kind of Lego building block construction, many different tuners became possible. Depending upon the country of destination and its associated standard and IF settings, the required filter modules would be selected. Service workshops and tv fabricants could later even add or exchange modules when new channels were introduced, since every inductor module had its individual factory code and could be ordered separately. As a consequence more versions of the tuner were produced, covering at least standards B, B-for-Italy, C. E, F and M.


The principle of the drum tuner. On an axis two times 12 regularly spaced channel-specific filter modules are mounted. In front are twelve channel filter modules for both the channel filter and LO tank circuit tuning. Seven contacts are available, and one module is shown removed. The second row contains 12 modules with five contacts for the input filter circuit. In the tuner module the front section (for mixer-ocillator and channel filter) is separated by a metal shield from the rear RF input and pre-amp section. [Philips Service "Documentatie voor de kanalenkiezers met spoelenwals", 1954]

Examples of the filter modules as used in the drum tuner. Left the 5-contact input filter, right the 7-contact BPF and LO tank filters. In both modules the coils are co-axial for (maximum) mutual coupling.





The second new valve introduced in the tuners family was the PCF80, a triode-pentode combo valve specifically designed for the VHF mixer-oscillator role. First order the circuit principles didn't change too much from the previous ECC81 based generation, with the triode acting as a Colpitts oscillator with a tuned feedback from anode to grid. The oscillator voltage was minimally 5V at the grid, and would be inductively coupled to the input of the mixer pentode. This inductive coupling was achieved by putting the oscillator coil S7 and the BPF coils S5 and S6 on the same rod inside the drum tuner filter modules, see Fig.5 above. By adjusting the distance between these coils for each channel filter module, the coupling constant could be kept more or less constant across all channels, providing as much as possible a frequency-independent mixer performance. For the mixer the pentode replaced the previous triode, providing more feedback isolation between anode and grid. All in all the new tuner must have given a considerable performance improvement compared to the previous generation.