DE1019711B - Circuit arrangement for an automatic frequency control, in particular for reflex klystron oscillators - Google Patents

Description

GERMAN

The invention relates to automatic frequency control devices.

Reflex klystron oscillators can be independently controlled in frequency in various ways will. An example of a type of control that is preferred in many cases is in British Patent 670,238. The output of a common discriminator becomes this used to control the reflector voltage of a klystron, with the change in mixer output, Due to the rule change of the cup circle, the cup circle adjustment is used automatically to continue or to reverse, depending on whether and how the pot circle vote affects the outcome of the The mixer is enlarged or reduced. This enables an automatic optimum adjustment of the pot circle within its large or wide frequency range, so that always a certain extent the short-range reflector voltage regulation for the correction of fast frequency deviations is available; it also has the added benefit of having an optimum power output or an optimal output power is achieved at the same time.

A different type of control is used when a suitable system parameter (e.g. the power output in the case of the aforementioned UK Patent 670,238) not for tax purposes can be used in addition to the discriminator output. Controlling both the reflector voltage as well as the pot circle tuning is therefore set up in such a way that it passes through the discriminator output is effected, either in whole or in part. The present invention relates to however predominantly the first type of control circuit arrangements.

Difficulties arise
systems when the
which is the oscillator frequency

is only available during short periods, which are separated by substantially longer periods are separated.

If, for example, in a control circuit arrangement of the type according to the invention, it is necessary to compare the oscillator frequency with a reference frequency that is transmitted, for example, from a transmitter, which groups of pulses, for example 0.5 μβεΰ (microsecond) pulses with a pulse frequency of 50 kilohertz, sends out during 40 milliseconds and then remains silent for longer periods of, for example, 460 milliseconds, then the error information is not available for a sufficiently long time, i. i.e., the groups of pulses do not last

such control reference frequency, compared with

Circuit arrangement for automatic frequency control, in particular

for reflex klystron oscillators

Applicant:

National Research Development
Corporation, London

Representative: Dipl.-Ing. E. Schubert, patent attorney,
Siegen (Westphalia), Oranienstr. 14th

Claimed priority:
Great Britain October 15, 1951

Stanley Ratcliffe, Great Malvern, Worcestershire

(Great Britain)
has been named as the inventor

a long enough time. The reflector voltage regulation can of course respond in a very short time, and a large capacitor connected to the reflector ensures that the correct Reflector voltage not only between the pulses of a group, but also between the groups of pulses is sustained until the next group of pulses turn the correction Makes reflector voltage possible. The slow moving mechanical pot circle tuning is but unable to take effect during the short period of time which a group of Pulses are available and they cannot be used during the longer periods between the pulse groups being controlled. In the example given in British patent specification 670 238 it can be seen that the changes in the output power of the oscillator, which the pot circle tuning controls, only occurs when the reference frequency is available, what, on the present typically applied only for 40 milliseconds out of a total of 500 milliseconds would be the case.

The purpose of the invention is therefore to create an automatic frequency control system for klystron oscillators, in which the frequency control by pot circle regulation and by reflector voltage regulation which is effected in the

¹ TO 803/247

Is able to work under operating conditions in which the reference frequency is only used for short periods available, which are separated from each other by much longer periods. In cases of this Way where the reference frequency consists of a train of pulses, it is a purpose of the invention to provide a To create an installation of such a nature that it can take effect when the pulse train groups of pulses includes which by periods from each other

FIG. 2 shows a graph with an output power curve for the system according to FIG. 1, based on the Reflector voltage,

3 shows a further curve for the output power of the system according to FIG. 1, based on time, 4 shows a section of part of a reflex klystron,

Fig. 5 shows a tuning control motor circuit arrangement, while

Fig. 6 shows another circuit arrangement for a

are separated, which reproduces as long compared to the length io tuning control motor,
to be addressed in a group. In the block diagram of FIG. 1, a mixer 1

supplied from a terminal 2 to which

The automatic frequency control device for reflex klystron oscillators described at the beginning The discriminator and mixer stage are

Voltage source of a (not shown) reference frequency oscillation is switched on, as well as of Finding improved primarily in such a way that 15 a connection 3 forth, which to the output of a when the reference oscillation for a (also not shown) klystron oscillator is interrupted

is switched on, to which the desired automatic frequency control is to be transmitted.

The voltage source for the reference frequency supplies

for a certain period of time the DC voltage value of the reflector voltage is held and with an AC voltage is superimposed and that as a result of this

Reflector voltage corresponds to the pot circle tuning - 20 pulse trains with the reference frequency, the im-

speaking of the changes in phase and amplitude pulses last 0.5 microseconds and become with

is controlled in the output of the mixer so that a pulse frequency of 50 kilohertz repeat,

an optimum of the output power ^{1 of} the oscillator The pulse trains have a duration of 40 milliseconds

tors adjusts. the, between which pauses of 460 milliseconds

According to a further feature of the invention 25 are present. Often the voltage source is used for

are the means, which the superimposition of the reflect the reference frequency designed as a transmitter, which

cause gate voltage, designed as switching means, a receiver is assigned, from which the to be controlled

which separate the discriminator from the reflector, the oscillator forms a part,

when the reference oscillation ceases, it is available. The mixer 1 supplies a discriminator 4;

to stand, and which a low frequency generator 30 this has the usual structure and provides a

to switch on the reflector, whereby a memory input output, which for the extent of the detuning

direction to the reflector is turned on to (i.e., in sense and size) the oscillator

the last corrected value of the reflector voltage relative to the reference oscillation. the

as an indirect bias to maintain both frequencies are not necessarily

which around the low frequency generator output 35 is identical; rather the frequency of the oscillator

which causes vibration.

Preferably, the coupling of the low frequency generator to the reflector circle is via a Transformer causes its secondary winding

also have a certain frequency difference compared to the reference oscillation. In general the latter operating state will be the norm. The output of the discriminator 4 is a

between the discriminator and the reflector, 40 contact RA and a contact RN A2 the reflector

wherein the switching means are set up so that the secondary winding of the same is short-circuited, when the reference oscillation is available. The storage device can have a capacitor, which to the discriminator side of the transformer secondary winding is switched on.

Finally, the invention also relates

ensure that a phase-sensitive rectifier is provided in the control circuit of the pot circle tuning

which is connected to the mixer stage output in 50 the reflector voltage
commitment. The pot circle control device can frequency during the
be set up so that they correspond to the sign and amplitude of the pot circle cavity
The output of the phase sensitive rectifier.

These circuit arrangements ensure an optimal effect of the pot circle tuning in the Reaches periods during which the reference frequency is not available; moreover takes place

tor of the oscillator. Contact RA is controlled from an appropriate point on the reference vibratory system so that it is closed only during the 40 millisecond pulse trains; the contact RXA2 short-circuits the secondary winding of a transformer T during the pulse trains and will be dealt with in more detail below. In this way, the output of the discriminator 4 is effective in such a way that it

and thus the oscillator controls short pulse trains.

During the much longer intervals or pauses, however, the reflector is separated from the discriminator 4, and therefore a capacitor C is provided and connected to the reflector in such a way that it maintains the mean corrected reflector voltage until the next pulse train begins. It is obvious that the reason

voltage, which the reflector for the work of the pot circle tuning when the reference oscillator needs 60 is available by other, known switching frequency, so slowly (if medium is supplied, but that for the invention at all) that the frequency control during
such periods by the reflector voltage control alone within a practically permissible
Error area is executed.

The invention will now be described in more detail with reference to the drawing showing it as an example 1 shows a schematic diagram of a circuit arrangement

an automatic frequency control system,

are not essential and can easily be provided by a person skilled in the art, for example by applying a corresponding bias voltage in the discriminator output. The contacts RNAl and RKA 2, which are set up so that they are only actuated during the intervals between the pulse trains, are each effective to connect the grounded primary winding of the transformer T to a low-frequency voltage source G.

to connect and to separate the short circuit of the secondary winding of the transformer T , which is provided in the reflector control circuit. Then, during the longer interval between the pulse trains, the reflector voltage has a superimposed low frequency with a sinusoidal wave shape due to the action of the transformer T. This change in reflector waveform causes the oscillator power output to change accordingly. In this way, there is also a change in the output of mixer 1.

The frequency of the alternating current source T can expediently be of the order of 50 to 1000 Hertz.

The mode of operation can be seen in detail from the curves in FIGS. In Fig. 2, the curve of the oscillator power output (ordinate), based on the reflector voltage (abscissa), is shown, with sinusoidal changes in the reflector voltage, which mean values of the reflector voltage corresponding to the various deviations from the maximum value pot circle dimension for a maximum output power value are superimposed at I and II are indicated; χ corresponds to the deviation from the maximum value cup circle dimension in one sense, while X corresponds to the deviation in the other sense. The sinusoidal changes cause sinusoidal changes in the output power of the mixer 1, the phases of the change having opposite signs depending on the direction of the deviation or its sense. The amplitude of the output power changes with the frequency of the voltage source G corresponds to the extent of the deviation from the maximum value or optimum. The output power changes are shown in Fig. 3, in which the curves I α and II α correspond to the deviations χ and X in the opposite sense., Where χ is less than X.

The output from mixer 1 is transmitted to pot circle control device 5. In the pot circle control device 5, the beats or superimpositions of the direct current component of the output of the mixer 1 are fed to a phase-sensitive rectifier in a manner known per se. This rectifier can be of known shape and receives its reference voltage from generator G. The DC voltage component of the output of the mixer 1 is proportional to the output power of the klystron oscillator and shows the corresponding changes due to the sinusoidal change in the reflector voltage through the generator G. The output of the phase sensitive rectifier therefore has a polarity corresponding to the phase or antiphase relationship between the DC voltage component changes and the output of the generator G, and it has a value which corresponds to the amplitude of the changes. The output of the phase-sensitive rectifier therefore corresponds in terms of its polarity to the sense or sign of the deviation of the cup circle control from the optimum point for a maximum output power value and in relation to its size to the extent of the deviation of the cup circle adjustment from the optimum point.

The output of the phase-sensitive rectifier is expediently transmitted to the circuit arrangement shown in FIG. This circuit arrangement supplies the motor m, λνεΙΛεΓ causes the pot-circle tuning of the klystron in accordance with the size and polarity of the rectifier output.

In the circuit arrangement according to FIG. 5, the output of the phase-sensitive rectifier is transmitted to a terminal 6 which is led to the grid of a pipe 7 via a grid resistor 8. The tube 7 and a second tube 9 together form the control amplifier, in the anode circuits of which the field coils 10 and 11 of the motor m are switched on. ίο A generator g, which sits on the shaft of the motor m , is connected to the grid of the pipe 7 via an integration circuit, which consists of a resistor 12, a capacitor 13 and the series resistor 14. Depending on the polarity of the output at terminal 6 from the phase-sensitive rectifier, either pipe 7 or pipe 9 conducts current, and a current flows either in field coil 10 or in field coil 11. Since these coils are connected in opposite directions as field coils, the motor rotates m either in one or the other direction, depending on the polarity of the signal at terminal 6.

The characteristics of the pot circle tuning drive, for example its inertia, can be determined in a known manner by suitable dimensioning and design of the generator g and the integrator circuit 12, 13 and 14.

The manner in which the motor m is brought into connection with the pot circle of the klystron can be seen from FIG. The shaft 15 of the motor m is provided with a screw thread at its end 16 and runs in a nut 17, which is connected to the tuning piston 18 of a reflex klystron cup circle 19 in such a way that by rotating the motor shaft 15 the tuning of the Cup circle 19 is changed. The klystron tube itself is only partially shown and has a reflector 20, a cathode 21 with a filament 22 and a bundling device 23. The walls 24 and 25 of the outer cup circle 19 extend into the glass envelope 26 of the klystron tube cup circle 19 by means of copper washers 27 and 28 which are fused into the envelope 26. The exit of the klystron is taken from the circle 19 by means of the probe 29.

Another embodiment for the resonant cavity tuning control is shown in FIG. 6. In this the output of the mixer is connected to a terminal 30 and from there via an amplifier 31 to a phase winding 32 of a two-phase motor M 1 (FIG. 1). The motor M is coupled to the klystron cup-circle piston system 18 (FIG. 4), as described above, while the second phase winding 33 is connected to the alternating current generator G (cf. also FIG. 1) via a 90 ° phase shift circuit 34 ) is connected, which supplies the alternating voltage for the reflector circle of the klystron.

It is not difficult to see that if the mixer output is a direct current (no change, because the pot circle tuning is at the optimum power operating point), only one phase winding 33 of the two-phase motor M is excited and the motor therefore does not rotate. If, however, the mixer output changes in the low frequency rhythm to thereby indicate a deviation from the optimum of the pot circle tuning, then both phase winding 32 and winding 33 are energized and the motor M rotates around the klystron pot circle according to the phase of the output from the amplifier 31 ", which in turn declines

depends on the sign of the deviation from the optimum. Furthermore, the fact that the excitation of the winding 32 becomes greater, the greater the deviation of the pot circle tuning from the optimum, in a corresponding manner Way, the adjustment accelerated.

Claims (5)

Patent claims: 1. Automatic frequency control device for reflex klystron oscillators with a discriminator, its dependent on the difference between the oscillator frequency and a reference frequency Output voltage is used to regulate the reflector voltage of the klystron, and with a mixer to which the oscillator oscillation and the reference oscillation are fed and whose output voltage adjusts the pot circle to an optimum of the oscillator output power controls, characterized in that when the reference oscillation is interrupted for one certain period of time the DC voltage value of the reflector voltage is held and with a AC voltage is superimposed and that, as a result of this reflector voltage, the pot circle tuning controlled according to the changes in phase and amplitude in the output of the mixer that an optimum of the output power of the oscillator is established. 2. Circuit arrangement for an automatic frequency control device according to claim 1, characterized characterized in that the means which cause the superposition of the reflector voltage as Switching means are formed which separate the discriminator from the reflector when the Reference oscillation ceases to be available stand, and which connect a low frequency generator to the reflector, with a memory device connected to the reflector to obtain the last corrected value of the reflector voltage as the mean bias around which the low frequency generator output lets the reflector voltage fluctuate. 3. Circuit arrangement according to claim 2, characterized in that the coupling of the Low frequency generator is effected to the reflector circuit via a transformer, whose Secondary winding lies between the discriminator and the reflector, the switching means so are set up so that the secondary winding of the same is short-circuited when the train oscillation is available. 4. Circuit arrangement according to claim 3, characterized in that the memory device has a capacitor which is connected to the discriminator side of the transformer secondary winding is turned on. 5. Circuit arrangement according to claim 1 to 4, characterized in that the control circuit Pot circle tuning a phase-sensitive rectifier is provided, which with the Mixer stage output is in communication, and that a pot circle control device is provided is that they adjust the pot circle cavity according to the sign and amplitude of the output of the phase-sensitive rectifier tunes. Considered publications:
French Patent No. 924,748;
U.S. Patent No. 2,565,842. 1 sheet of drawings © 709 806/247 11:57