DE1153449B - High frequency generator for industrial purposes - Google Patents

Description

GERMAN

PATENT OFFICE

N12286IXd / 21d ^a

REGISTRATION DATE: MAY 29, 1956

NOTICE THE REGISTRATION AND ISSUE OF EDITORIAL: AUGUST 29, 1963

The invention relates to a high-frequency generator for industrial purposes with a generator tube in three-point circuit, in particular with generation of a partial feedback voltage in the capacitive branch (Colpitt circuit), with the resonant circuit coil in the anode circuit being symmetrical to ground executed oscillating circuit with one in the load circuit, one-sided, preferably on a center tap grounded coupling coil is coupled, in which the anode voltage for the Generator tube taken from an anode voltage source grounded on one side via a high-frequency choke will.

In such high-frequency generators with a generator tube in three-point circuit, in particular in Colpitt circuit, the anode voltage source was connected to the with to feed the generator tube the grounded center point of the capacitive voltage divider connected to the cathode of the tube and the The center of the resonant circuit coil is switched so that the resonant circuit coil, which is used at the same time The supply of the anode voltage is used, an alternating generator voltage balanced to ground is also created an amplitude that is equal to the size of the anode voltage. To increase the performance it is known here to train the high-frequency generator in push-pull, the grounded center tap the resonant circuit coil is connected to the center tap of a supply voltage transformer, which is connected between the cathodes of the generator tubes.

When increasing the power, it was found in such high frequency generators that the Adaptation area, d. H. thus the area within which an optimal power transfer to the load can be achieved, is very greatly reduced and at the same time the benefit is not the Meets expectations. By carefully investigating this behavior in high frequency generators of the type indicated at the beginning, it was found that this influence the adjustment control area and the useful effect, along with other possible causes, mainly in the leakage inductance the transformer coupling of the resonant circuit coil and the coupling coil sought must be, it has been shown that the leakage inductance is particularly troublesome on the The resonant circuit of the high-frequency generator acts back.

The invention aims at a substantial improvement of the adaptation area and the efficiency in the case of high-frequency generators of the type specified, high-frequency generators for industrial purposes

Applicant:

N. V. Philips' Gloeilampenfabrieken, Eindhoven (Netherlands)

Representative: Dr. rer. nat. P. Roßbach, patent attorney, Hamburg 1, Mönckebergstr. 7th

Claimed priority: Netherlands of 3 June 1955 (No. 197 782)

Lourens Blök, Jacob Willem de Ruiter,

Sijtze Johannes Cornells Sijtsma

and Gooitzen Zwanenburg, Eindhoven (Netherlands),

have been named as inventors

at the same time a more robust construction of the high-frequency generator is achieved.

The high frequency generator according to the invention is characterized in that at negligible small feedback partial voltage anode and cathode of the generator tube with one of two on each side, of the earthing point are connected to the points of the resonant circuit opposite each other Earth approximately half the circular alternating voltage with an amplitude approximately equal to half the anode direct voltage leads, the cathode in a manner known per se via a high-frequency choke at the anode voltage source lies.

When the new measures are applied, an alternating voltage that is symmetrical to the ground is created on the resonant circuit with an amplitude approximately equal to half the anode voltage, together with that the Components are not so highly stressed due to the reduction in the insulation requirements between the resonant circuit coil and Coupling coil, the distance between these coils can be significantly reduced, so that thereby a substantial reduction in the leakage inductance is achieved, with the result that in particular In the case of high-frequency generators with higher power, the adaptation area and the efficiency are very important be improved. So was z. B. in a high frequency generator of 25 kW, together with a Efficiency improvement of 10%, the adaptation area enlarged by a factor of 4 to 5.

309 669/115

At this point it should be noted that in transmitter amplifiers it is known per se, the anode voltage source to be connected to the anode and the cathode of the tube via high-frequency chokes, in particular this measure is applied to the anode voltage, the two connected in series Rectifiers with a grounded connection point is taken to feed the tube. In this Circuit, however, is not one

The resonant circuit of the oscillator, which oscillates in a Colpitt circuit, is connected to one that determines the oscillator frequency Oscillating circuit 2, which consists of an oscillating circuit coil 3 and a circular capacitance, which in turn consists of a capacitive voltage divider with a capacitor 4 and one with this series-connected capacitor 5 with three plates. The anode of the triode 1 lies over a Separating capacitor 6 on the one with the resonant circuit

the tapping point consists of the middle of the three layers. The grounded tubular cathode is with a Connection point of the capacitors 4 and 5 verIf the circuit arrangement oscillates, results An alternating voltage which is symmetrical with respect to the earth occurs at the resonant circuit coil 3; half

High-frequency generator for industrial purposes, and io coil 3 connected end of the capacitor 4 and this circuit arrangement also lacks the rest of the high-frequency inductor 7 measures of the high-frequency generator according to the invention that is applied by a smoothing capacitor 9 balanced output circuit, so that is bridged. The control grid of the triode 1 is in the high-frequency 15 according to the invention via a grid capacitor 10 with leakage repeater for high-frequency heating technology was 11 at a tap point of the capacitor 5; achieved very important advantages not achieved
will.

Furthermore, it is known to achieve a defined position of a measuring oscillator in the electromagnet! - 20 bound; this connection point forms roughly the space, whereby it is not permitted to directly ground a point in the electrical center of the oscillating circuit 2. of the measuring oscillator, two places
of the circuit via capacitors to earth, so that disruptive stray fields and leakage currents are eliminated. In this circuit arrangement, too, the circuit voltage is approximately the same as the anode DC voltage, and the structure and effect are substantially different from voltage. The new high-frequency generator, which is fed to a load circuit 13 at high output power, is fed via a coupling coil 12. Bringing significant benefits to services. For this purpose it is noted at the output terminals 14, 14 'in the end that the coupling coil 12 is known to have a work coil 15, in the case of a high-frequency transformer the middle of the 30 is connected, in which a workpiece 16 to be heated is connected to the secondary coil To lay earth, whereby the danger is ordered. the damage to the insulating layers is reduced. It turned out that with this well-known

It has also been shown that in the training embodiment of a high frequency generator, in which the tube is directly heated and via a special heating transformer from an alternating voltage transformer with variable coupling, such as is fed to the source, in the Practice particularly favorable adaptation to the load is common, in practice be-successes are achieved. In a first training special disruptive scattering losses occur, the form is the connected to the cathode line. A high-frequency high-frequency choke coil consisting of two choke coils, generator according to the invention will now be explained in more detail with reference to FIG. In Fig. 2 over which the cathode ends on the secondary winding 40 are the parts corresponding to FIG. 1 with the lines of the heating transformer. Denoted in a second chen reference numerals. The high-frequency generator shown in Fig. 2 with the secondary winding of the heating transformer contains a directly heated triode 1, which is connected from a, while the ends of the primary winding are bridged by a smoothing capacitor 9 each via a choke coil at the AC voltage source 8 is fed. The cathode source lie, while in a third training the heating current for the tube is not shown, the cathode line choke coil with one of the
Cathode ends connected and for prevention
of high frequency voltages on the primary side of the
Filament transformer, the secondary winding of this 50th
Transformer in one with protruding flanges
provided metal shield is arranged to
connected to earth at one point.

For these three that are particularly important in practice

Forms of training will only form part of the oscillating circuit capacity within the framework of the main 55. The

demanding protection. Capacitor 22 resulting voltage is called the return

placed AC voltage source and taken via input terminals 17, 17 'and a heating transformer 18 fed to the tube heater.

The triode 1 is in turn inserted into an oscillator in a Colpitt circuit; the anode circuit contains an oscillating circuit 19 with an oscillating circuit coil 20, which is connected by a capacitive voltage divider Capacitors 21 and 22 is bridged, the one

The invention and its advantages are explained in more detail below with reference to the figures.

Fig. 1 shows the circuit diagram of a known high frequency generator :

Fig. 2 shows an embodiment of a high frequency generator according to the invention;

Fig. 3 shows a modified embodiment of the circuit arrangement of FIG. 2, while

coupling voltage fed through a grid capacitor 10 to the control grid of the tube.

In the same way as in the circuit arrangement according to FIG. 1, the anode resonant circuit is inductive Via a coupling coil 12 which, together with the resonant circuit coil 20, forms an output transformer forms, coupled to a load circuit 13. The resonant circuit coil 20 is connected to a grounded center

Figure 4 illustrates a preferred embodiment. 65 tap 23 provided. The anode of the triode 1 is

In the circuit arrangement according to FIG. 1, on the one hand, the isolating capacitor 6 is

High-frequency energy through a high-frequency connection point of the capacitor 21 and the oscillation

rator generated with a triode 1. The tuned circular coil 20 is coupled and is on the other hand over

the high-frequency choke coil 7 at the anode voltage source 8. The cathode of the triode 1 is with the tapping point of the voltage divider 21, 22 and furthermore via heating current lines 24, 24 'with in these switched choke coils 25 and 25 'are connected to the secondary winding 26 of the heating transformer 18. The latter is bridged by two series-connected capacitors 27, 27 ', the Connection point of these capacitors with earth

32 is again provided with a grounded tap. In contrast to the circuit arrangement According to FIG. 2, however, the grounded tapping point of the anode circuit here consists of the grounded one Tapping point of a capacitive voltage divider connected between the ends of the circuit, which turns off the series connection of capacitors 34, 35 and 22 as seen. The voltage divider capacitors 34 and 35 are to replace the voltage divider capacitor

connected is. The grounded terminal of the io 21 according to Fig. 2 between anode and cathode is

Anode voltage source 8 is connected to the center of the secondary winding 26 of the heating transformer 18.

The in this circuit arrangement on the

switches. The connection point of the capacitors 34 and 35 is to ground. This kind, the oscillating circuit grounding is favorable from a structural point of view and also has the advantage that the changeable

between the anode and cathode connected part of the 15-speed transformer can be designed in such a way that it is safe

The oscillating circuit resulting high-frequency alternating voltages are, as well as in the circuit arrangement according to Fig. 1, in amplitude approximately equal to the anode voltage. In contrast, that the resonant circuit coil can be moved in the axial direction in the coupling coil.

Another difference compared to the circuit arrangement shown in FIG. 2 consists in the

Above the known circuit arrangements are each 20 formation of the heating circuit of the triode 1. The but both the anode and the cathode of the cathode heating is here namely via the heating triode 1 via choke coils to the grounded anode power lines 24, 24 'directly to the secondary voltage source connected, and the resonant circuit winding 26 of the heating transformer 18 connected, is provided with a grounded center tap, so that the cathode connected to the resonant circuit the two ends of the circle only half of the end of the circle alternating with a high-frequency choke coil 36 show voltage to earth. For example, if the grounded terminal of the anode voltage die Triode 1 with a DC anode voltage from source 8 is connected. The primary winding 37 of the about 12 kV is fed, can with an alternating heating transformer 18 is via choke coils 38, 38 ' voltage of, for example, 1 kV connected to the input terminals 17, 17 'via a capacitor 22 the total circuit voltage will be about 13 kV. The 30 which an alternating voltage source, not shown AC voltage at the ends of the circle is then.

However, due to the grounding of the center of the circular coil, the primary heating transformer circuit is over

20 only about 6.5 kV to earth. connected to the input terminals 17 and 17 '

In other words, the voltage between the decoupling capacitors 39, 39 'is symmetrical with Resonant circuit coil and the coupling coil is connected in 35 earth.

Compared to the known circuit arrangement, for example, to limit the amount in the primary winding 37

halved, resulting in a corresponding reduction and the iron core of the filament transformer IS induder Isolation requirements is achieved. The removed high-frequency voltages are the transstand between the resonant circuit coil and the coupling formator windings 26, 37 through two condensing coils can now to reduce the 40 capacitors 40, 40 'coupled to each other via which the Scatter of the output transformer significantly different ends of the primary winding 37 and be reduced. the secondary winding 26 are connected to one another.

For ease of use, the high-frequency circuit in this embodiment includes the heating circuit

Generator according to FIG. 2, the inductors 38, 38 'lead the primary current into the control grid circuit switched start-stop switch 28. In the illustrated 45 of the filament transformer; this stream is much smaller Position this connects the control grid of the triode 1 as the heating current itself. This results in Via the series connection of a high-frequency choke, the advantage that the choke coils 38, 38 '. despite the coil 29 and a grid resistor 11 with earth, whereby tubes for large power related large through the generator oscillates. The grid resistance heating currents (about 100 A), in terms of their dimensions 11 is for decoupling for high frequency voltages 50 solutions are made relatively small bridged by a decoupling capacitor 30. can.

The mode of operation of the circuit arrangement essentially corresponds to that with regard to FIG. 2 given explanations; after the explanation given on the basis of this FIG. 2, it should only be noted that by appropriate mutual sizing

When the start stop switch 28 is flipped to the position not shown, the control grid is circle connected to a negative grid bias source 31, thereby blocking the triode 1.

FIG. 3 shows a modified embodiment of the high-frequency generator shown in FIG. Appropriate Elements are in turn with the same

the capacitors of the voltage divider 34, 35, 22 connected between the circuit ends are symmetrical Stress on the circle opposite

denoted reference numerals.

The embodiment of Fig. 3 contains, as well as So earth can be achieved.

like the circuit arrangement according to FIG. 2, one in FIG. 4 represents a variant of the embodiment

Fig. 3, which has proven to be advantageous in practice. Corresponding elements are again denoted by the same reference numerals.

In the embodiment shown in FIG. 4, the one connected to the anode circuit of the triode 1 is on the operating frequency matched anode vibration

directly heated triode 1 used in an oscillator. In the anode circuit of triode 1 is an anode resonant circuit 32 connected to an oscillating circuit coil 33, which together with the in the load circuit 13 connected coupling coil 12 forms an output transformer for load adjustment is designed to be changeable. The oscillating circuit

circle 41 as well as the circuit arrangement

3 via the grounded tapping point of a capacitive one connected between the ends of the circle Voltage divider connected to earth.

The capacitive voltage divider in this embodiment consists of a series connection of four Capacitors 42, 43, 44 and 22. Voltage dividing capacitors 43 and 44 are the same Capacitance value and are connected between the anode and cathode of the triode 1. The connection point these capacitors are connected to earth. The capacitor 42 is between the anode and the adjacent one The end of the oscillating circuit is switched and has the same capacitance value as that created by the voltage divider capacitor 22 between the cathode and the end of the oscillating circuit adjacent to the cathode effective capacity. In this way, the grounded tap of the voltage divider forms 42 bis 44, 22 is the electrical center of the circle, whereby both those at the anode and at the cathode as also the alternating voltages resulting at the oscillating circuit ends symmetrically with respect to earth are. If the anode alternating voltage of 12 kV results on the triode 1, they are alternating voltages resulting at the anode and the cathode each 6 kV to earth and im Balance; the alternating voltages resulting at the oscillating circuit ends are then for example 7 kV to earth.

The heating current feed circuit differs from the embodiments described above in particular due to the special design of the filament transformer 45. The secondary winding 46 of the Heiz'cransformators 45 is arranged in a grounded metal shield, which preferably consists of a there is a copper or brass shielding cylinder 48 provided on both sides with protruding flanges 47, which is provided with an axially running saw cut at one point to prevent short-circuit currents is.

The secondary winding 46 is, similarly to the embodiment shown in FIG. 3, directly connected to the ends of the tube cathode having high-frequency potential. In this embodiment of the heating transformer, the high-frequency field, which is generated by the high-frequency voltages on the secondary winding 46 , ends practically completely at the shielding cylinder 48 and the flanges 47, so that the primary winding 49 and the iron core of the heating current transformer 45 are effectively shielded. The primary winding 49 is in this case connected directly to the alternating voltage source, not shown in detail, from which the heating current feed is taken, even without the intermediary of choke coils. The cathode line choke coil is here, as in the embodiment shown in FIG. 3, connected to one of the cathode ends. It is readily apparent that the different heating current feed circuits, as they have been described in the embodiments shown in FIGS. 2, 3 and 4, can be interchanged.

From a structural point of view, it is sometimes advantageous to replace the resonant circuit coil with an additional, between to bridge the resonant circuit ends of the switched capacitor 50, as shown in FIGS. 2, 3 and 4 is indicated by dashed lines. In this way it is achieved that through the connected between the circle ends capacitive voltage divider only part of the total circuit current flows through it, so that capacitors can be used with air as a dielectric; with consideration of the manufacturing costs is this beneficial.

Finally, it should be noted that the invention described above does not apply to the Embodiments shown capacitive feedback oscillator is limited, but of course can also be used when the triode 1 is inductively fed back.

Claims (7)

PATENT CLAIMS: 1.High-frequency generator for industrial purposes with a generator tube in a three-point circuit, in particular with the generation of a partial feedback voltage in the capacitive branch (Colpitt circuit), the resonant circuit coil of a resonant circuit constructed symmetrically to in which the anode voltage for the generator tube is taken from an anode voltage source grounded on one side via a high-frequency choke, characterized in that, with negligibly small feedback partial voltage, the anode and cathode of the generator tube are each connected to one of two points of the resonant circuit located on either side of the grounding point, each of which is approximately connected to ground leads half the circular alternating voltage with an amplitude approximately equal to half the anode direct voltage, the cathode in a manner known per se via a high-frequency choke at de r anode voltage source is present. 2. High frequency generator according to claim!, Characterized characterized in that the coupling between the resonant circuit coil (33) and the coupling coil (13) is variable and the grounded tap of the oscillation circuit (33, 34, 35, 22) from the grounded tap of a between the circuit ends of the switched capacitive voltage divider (34, 35). 3. High frequency generator according to claim 2, characterized in that the capacitive voltage divider from at least three series-connected voltage divider capacitors (34, 35, 22) viewed, of which two capacitors (34, 35) between the anode and cathode of the generator tube (1) are connected, the grounded tap of the capacitive voltage divider being the grounded The connection point of these two capacitors is, while one is between the tube cathode and the adjacent end of the resonant circuit connected third voltage divider capacitor (22) a dem Control grid fed feedback voltage is taken. 4. High frequency generator according to claim 3, characterized in that the two between Anode and cathode of the generator tube (1) connected voltage divider capacitors (43, 44) have the same capacitance values that the capacitive voltage divider has a fourth voltage divider capacitor (42), which is connected between the tube anode and an oscillating circuit end, and that the fourth voltage divider capacitor has the same capacitance value as that between the cathode and the neighboring oscillating circuit switched third voltage divider capacitor (22). 5. High frequency generator according to one of the preceding claims, wherein the generator tube directly heated and fed from an AC voltage source via a filament transformer is, characterized in that the high-frequency choke coil connected into the cathode line consists of two choke coils (25, 25 ') through which the cathode ends on the secondary winding (26) of the heating transformer (18). 6. High frequency generator according to claim 1, 2, 3 or 4, in which the generator tube directly is heated and fed via a heating transformer from an AC voltage source, thereby characterized in that the cathode ends are connected directly to the secondary winding (26) of the Heating transformer (18) are connected, while the ends of the primary winding (37) each have a Choke coil (38, 38 ') are connected to the AC voltage source. 7. High frequency generator according to claim 1, 2, 3 or 4, in which the generator tube directly is heated and fed from an AC voltage source via a heating transformer, so that 10 characterized in that the cathode line choke coil (36) with one of the cathode ends is connected and that to prevent high frequency voltages on the primary side (49) of the Heating transformer (45) the secondary winding (46) of this transformer in a with a protruding Flanged (47) provided metal shield (48) is arranged in one place connected to earth. Considered publications:
German patent specifications No. 336 779, 397 081,
309, 808 865, 871182; German patent application S 10019 Villa / 21a ⁴ (published on December 24, 1952); French Patent No. 652173;
"Philips' Technische Rundschau", December 1949, No. 6, p. 171; "Telefunken-Zeitung", issue 87/88, September
1950, p. 73; Rothe-Kleen, »Electron tubes as vibration generators and rectifier ”, Leipzig, 1941, p. 46; Limann, Otto, "Prüffeldmeßtechnik", 2nd edition, Munich, 1944, p. 16. 1 sheet of drawings