JPH09107248A - Traveling-wave-tube power amplifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fix the transmission output without especially increasing the power consumption even at the time of reduction of a supply voltage with respect to the supply voltage having a large voltage variance. SOLUTION: This traveling-wave-tube power amplifier is provided with a traveling-wave-tube power source 6 which varies the output voltage from the input voltage and supplies a DC voltage required for operation of a traveling- wave tube 3 to this tube 3, an input voltage detection means 9, and a preamplifier 2 which has the gain characteristic corresponding to the input primary voltage to the traveling-wave-tube power source 6. As the result, the beam current of the traveling-wave tube 3 is reduced by a beam current adjuster at the time or reduction of the supply voltage, and the load is reduced and the gain of the preamplifier 2 is raised to fix the output power.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traveling wave tube power amplifying device for amplifying microwave band signals with large power, and more particularly to a traveling wave tube power amplifying device used in a portable transmission station.

[0002]

2. Description of the Related Art In a power amplifying apparatus using a traveling-wave tube for amplifying a high-frequency signal in a microwave band or the like, when the power supply voltage exceeds a specified value (for example, rated input voltage ± 10%), the traveling-wave tube is switched to the traveling wave tube. Generally, the operation is temporarily stopped to prevent application of an abnormal voltage. By the way, a portable transmitter station often uses an engine generator as a power supply, but the characteristic of this engine generator is that transient characteristics are not sufficient for sudden changes in load, especially when the load becomes heavy. There is a possibility of causing an instantaneous voltage drop. When the traveling wave tube power amplifying device is operated by using such an engine generator as a supply power source, unexpected transmission interruption may be caused during operation depending on whether power is supplied to devices other than the traveling wave tube power amplifying device. There are cases.

[0003]

In order to prevent the above-mentioned problems, a power generator having a larger capacity is conventionally prepared so as not to be affected by a load fluctuation, and an input operating range of a traveling-wave tube power amplifying device is provided. (For example, ± 15%). However, these methods have problems in that the mobility of the portable transmission station is reduced, the design is specially designed, and the economic efficiency is impaired.

[0004]

A traveling-wave tube power amplifier according to the present invention receives a preamplifier that amplifies a high-frequency signal and that has a variable amplification gain upon receiving a control voltage, and an output of the preamplifier. A traveling-wave tube that performs high-power amplification, a power-supply voltage is input, and a traveling-wave tube power supply that supplies a required operating voltage to the traveling-wave tube; and the power-supply voltage is input to correspond to the power-supply voltage A voltage detector that outputs a detection voltage, and an output voltage of the voltage detector are input, and a beam current adjustment that controls so that the beam current input to the traveling wave tube power supply decreases when the power supply voltage becomes a predetermined voltage or less. And the output voltage of the voltage detector is input, and when the power supply voltage becomes equal to or lower than a predetermined power supply voltage, the gain of the preamplifier is increased so as to compensate for the decrease in the amplification degree of the traveling wave tube due to the decrease in the beam current. With a gain adjuster A.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram showing an embodiment of a traveling-wave tube power amplifying apparatus according to the present invention. FIG. 2 shows the power supply input voltage versus the power supply input current and the related gain of the preamplifier according to the present embodiment.

In FIG. 1, a power supply voltage input to a power supply input terminal 5 is input to a traveling wave tube power supply (TWT PS) 6 and also to a voltage detector (DET) 9.
The voltage detector 9 supplies the traveling wave tube power supply 6 according to the detected voltage value.
Has a function of controlling the power supply voltage of the beam current regulator 7 and the preamplifier 2.

Here, when the output of the beam current regulator 7 is constant and the voltage at the input terminal 5 decreases, the voltage stabilizing circuit of the traveling wave tube power supply 6 operates, as shown in FIG. Thus, the input current of the input terminal 5 gradually increases.

[0009] As a result, the input current corresponding to the decrease of the power supply input voltage is in a linearly increasing, the maximum input current drop in the power supply input voltage is acceptable TWT power 6 at point b in FIG. 2 I _max It will increase to.

Therefore, the voltage detector 9 of the present invention detects the power supply input voltage, and in the case where the input voltage is up to point a in FIG. 2, the beam current regulator 7 outputs a control voltage so as to output a constant beam current. However, the control voltage is output so as to reduce the beam current output of the beam current regulator 7 when point a is exceeded.

As a result, the input current becomes the maximum input current I
Before reaching the _maximum , the increase in the beam current is moderated, and as shown in FIG. 2, only a slight increase in the input current is performed.

[0012] Here, c point of the input voltage in FIG. 2 increases the input current is gradually, eventually protection when it reaches the maximum input current I _max circuit is a voltage to operate. Therefore, comparing the case where the beam current regulator 7 has a constant output current and the case where the control by the voltage detector 9 of the present invention is performed, the input voltage decreases and the input current reaches the maximum input current. The critical voltage can be extended from point b to point c. On the other hand, when the beam current is reduced by the control of the beam current adjuster 7, the gain of the traveling wave tube 3 is slightly reduced.
Are input to the gain adjuster 8 to increase the gain of the preamplifier 2. Therefore, the gain and output power of the entire apparatus can be kept constant by adjusting the control voltage 2 to the gain variable amount of the gain adjuster 8 to the characteristic of the gain reduction of the traveling wave tube 3.

FIGS. 3 to 5 show examples of specific circuit configurations of the beam current adjuster 7, the gain adjuster 8, and the voltage detector 9, respectively.

FIG. 3 shows the detection output from the voltage detector 9 as 7
1 and the beam current control voltage of the traveling wave tube power supply 6 is set to 7
6 is a circuit to output.

An operational amplifier 75 is used as an inverting amplifier, and a non-inverting input of the operational amplifier 75 is provided with a reference voltage setting device 74 for setting a beam current.

FIG. 4 shows a circuit in which the output voltage from the beam current adjuster 7 is input to 81 and is output from 86 to the gain adjuster 8 capable of varying the gain of the preamplifier 2. This circuit can also be configured using the inverting amplifier of the operational amplifier 84 as in FIG. Here, in order to optimally set the gain of the gain adjuster 8, the non-inverting input of the operational amplifier 84 is connected to the reference voltage setter 8
5 are provided.

FIG. 5 is a circuit for inputting a power supply voltage to 91 and outputting a detection voltage to 99. Here, the power supply voltage is
Assuming that the voltage is an AC voltage, after passing through a transformer 92, a rectification diode 93 and a smoothing capacitor 94 are used to perform rectification and smoothing operations to obtain a detection voltage. The detection voltage is input to the inverting amplifier by the operational amplifier 98, amplified to a predetermined voltage, and output.

Reference numeral 97 is a reference voltage setting device for setting the voltage at point a in FIG.

That is, when the DC voltage charged in the smoothing capacitor 94 is input to a normal power source, a constant voltage limited by the limiter diode 98 of the inverting amplifier is output.

However, the power supply voltage drops and the capacitor 9
When the DC voltage of 4 decreases, an output voltage that reduces the beam current output of the beam current regulator 7 is generated.

Although the present embodiment has been described with respect to a decrease in the voltage of the input terminal 5, it is sufficient to provide a margin with respect to an increase in the voltage of the input terminal 5 against the destruction of the device due to an excessive input. It is not necessary to consider the load characteristics of the power supply.

In this embodiment, the case where the beam current of the traveling-wave tube 3 continuously changes with respect to the input voltage of the input terminal 5 has been described. However, the same effect can be obtained by changing the beam current stepwise. It is clear.

[0023]

As described above, according to the present invention, the traveling wave tube power amplifying device can be operated more stably even when it is supplied from a power source having a large input voltage fluctuation such as an engine generator. ing. In particular, a portable transmission station that uses an engine generator can be operated even when the power supply drops, so that mobility can be improved, and the power supply capacity can be reduced, which is economical and compact. I can.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention.

FIG. 2 is a diagram showing an input voltage versus an input current and a gain characteristic of the preamplifier 2 according to the present embodiment.

FIG. 3 is a diagram showing a circuit configuration of a beam current adjuster 7;

FIG. 4 is a diagram showing a circuit configuration of a gain adjuster 8;

FIG. 5 is a diagram showing a circuit configuration of a voltage detector 9;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 High frequency input terminal 2 Preamplifier 3 Traveling wave tube 4 High frequency output terminal 5 Input terminal 6 Traveling wave tube power supply 7 Beam current regulator 8 Gain regulator 9 Voltage detector 72, 73, 82, 83, 95, 96 Resistance 75 , 84, 98 Operational amplifier 74, 85, 97 Reference voltage 95 Transformer 93 Rectifier diode 94 Smoothing capacitor 98 Limiter diode

Claims (4)

[Claims] 1. A preamplifier for amplifying a high-frequency signal, receiving a control voltage and varying the amplification gain, a traveling wave tube receiving an output of the preamplifier and performing high-output amplification, and a power supply voltage A traveling wave tube power supply that supplies a required operating voltage to the traveling wave tube; a voltage detector that inputs the power supply voltage and outputs a detection voltage corresponding to the power supply voltage; An output voltage is input, and a beam current adjuster that controls a beam current input to the traveling wave tube to decrease when the power supply voltage becomes equal to or lower than a predetermined voltage; and an output voltage of the voltage detector is input; And a gain adjuster for increasing a gain of the preamplifier so as to compensate for a decrease in amplification of the traveling wave tube due to a decrease in the beam current when a voltage becomes equal to or lower than a predetermined power supply voltage. Power amplifier 2. The method according to claim 1, wherein the voltage detector applies a constant voltage to the beam current regulator until the power supply voltage decreases to the predetermined voltage, and when the power supply voltage reaches the predetermined voltage, The traveling wave tube power amplifying device according to claim 1, wherein a voltage corresponding to a drop in input voltage is applied to the beam current regulator. 3. The traveling wave tube according to claim 1, wherein the predetermined voltage is a voltage before the power supply voltage decreases and an input current of the traveling wave tube power supply reaches a maximum input current. Power amplification device. 4. The voltage detector, comprising: a detector for rectifying and smoothing the power supply voltage; an output of the detector being input to an inverting input terminal of an operational amplifier; 4. The traveling-wave tube power amplifier according to claim 1, further comprising an inverting amplifier provided with a limiter diode in a feedback section of the operational amplifier.