JPS59228432A - Alc circuit of transmitter - Google Patents

Abstract

PURPOSE:To apply automatically automatic load control at a value being a ratio of prescribed rise and fall or over by providing an automatic load control voltage generating circuit activated only with the polarity of a DC component of a high frequency voltage proportional to the root of a power of reflected wave going backward from a feeder. CONSTITUTION:A high frequency voltage epsilonR proportional to the root of the power PR of reflected wave going backward from the feeder is obtained at other output terminal of a current transformer. A DC output ER is obtained by rectifying the voltage by means of diodes D1, D2. The automatic load control is applied automatically at a ratio S of rise and fall of a prescribed signal wave or over by providing an automatic load control (ALC) voltage generating circuit X activated only at the polarity of the DC output ER and the more the ratio of rise to fall is increased, the more the automatic load control becomes effective, thereby decreasing the output.

Description

Detailed Description of the Invention This invention passes transmission power to the primary side, transmits a high frequency voltage proportional to the square root of the traveling wave power to one output terminal of the secondary side, and transmits a high frequency voltage proportional to the square root of the traveling wave power to one output terminal of the secondary side. In this case, rectifier diodes are connected to both output terminals of a CM type directional coupler that generates a high frequency voltage proportional to the square root of the reflected wave power, so as to obtain outputs of opposite polarity, and the outputs of the diodes are connected. The load resistance is divided into two, and the traveling wave output side is a fixed resistance, and the reflected wave output side is a potentiometer or a resistance network in which a potentiometer and a fixed resistance are connected in series.

An ALC that controls the transmission output is applied to the meter's slider terminal by applying a DC voltage that is generated in direct proportion to the SWR value of the transmission output circuit.
The SWR value of the transmission output circuit is added to the ALC voltage generation circuit that converts it into a voltage, and the traveling wave side output voltage of the rectifier diode is used as the operation control input of the ALC voltage generation circuit through the control threshold setting circuit. AL of a transmitter is characterized in that it reduces the transmission output as the output increases, and does not generate an ALC voltage below the set output.
It is a C circuit.

In order for the transmission power sent out from the output amplifier of the transmitter to be completely radiated from the antenna as electromagnetic waves, the output impedance of the transmitter and the characteristic inductance of the feeder and antenna must match; When you are there,
A phenomenon occurs in which a portion of the power is reflected at the connection. Since the transmitter is usually tuned to match the characteristic impedance of the feeder, such reflections are often caused by a mismatch between the feeder and the load, and are reflected from the connection to the antenna. The reflected wave power (hereinafter referred to as reflected wave power) travels backwards within the feeder line and interferes with the output power of the transmitter (hereinafter referred to as forward wave power), creating a wave within the feeder similar to standing waves caused by sound wave interference. S
A consistent state is often expressed as wR (Standing Wave Ratlo). The value of this SWR is 1.0 when there is perfect matching and no reflection, and when the end of the feeder is open or shorted and total reflection occurs.

Mismatching in the transmitter output circuit not only reduces the effective radiated power, but also causes problems such as increased internal loss in the transmitting output stage and excessive applied voltage. In particular, since transistor amplifiers are vulnerable to reverse breakdown voltage, the degree of matching of the output circuit is important for the safety of the device. In practice, if it has to be used in a state with poor matching (high SWR), it is necessary to reduce the amount of output from the transmitter.

Figure 1 shows an example of a conventional circuit used for this purpose.The dotted line shows a CM-type force directional coupler, with the transmitter output at its primary input end and the antenna at its output end. When the feeder is connected, one output end of the current transformer M receives a high frequency voltage ε2 proportional to the square root of forward wave power p, and the other output end receives reflected wave power P going backwards from the feeder.
Since a high frequency voltage ε8 proportional to the square root of R is obtained,
The DC voltage E obtained by rectifying this with rectifier diodes D and D2.

and ER to synthesize ALC (Automatic Loa
d Control or Automatic Lev
Abbreviation of el Control) is used for voltage. In reality, it operates according to whichever of E or ER appears first, or whichever has a larger voltage, so a motion bias is added to D and D2 in advance, and the bias value is adjusted by vR4 and vR2. This sets the ALC operation level. Although this method has an extremely simple configuration, it has the disadvantage that the setting of the operating level must be readjusted as the usage conditions change.

Therefore, in the present invention, as shown in the embodiment shown in FIG. At one output end of the transformer, a high frequency voltage proportional to the square root of the traveling wave power P is obtained, and at the other output end, a high frequency voltage ε8 proportional to the square root of the reflected wave power PR traveling backward from the feeder is obtained. , which are rectified by rectifier diodes D and D2 connected in opposite polarity directions, the resulting DC outputs E and ER are obtained (5).If one is a positive voltage, the other is a negative voltage, so D, When a resistor is loaded between the output F and the output R of D2, the potential distribution on the resistor is as shown in Figure 3.
The distance between the straight line F'R' and FR connecting the tips F' and R' of R' corresponds to the potential on the resistor. Therefore F/R/ and FR
The intersection point Q is zero potential, and the positive and negative potentials are reversed on the F side and R side.

How the zero potential point Q determines the SWR will be explained below.

SWR is the value calculated by the following formula, which is the traveling wave voltage v
2. If the reflected wave voltage is v8 and the circuit impedance is R, it can also be expressed by dividing the denominator term and molecular ring in equation (6) (2) by V.

In Figure 3, ΔQFF' and ΔQRR' are congruent, so it can be determined.

Furthermore, since SWR=1 when the circuit is completely matched and there is no reflection, this means that the Q point coincides with the R point from equation (3).

Furthermore, since the SwR is ω when the circuit is in a total reflection state with the terminal open or short-circuited, from equation (3), RQ = FQ. This means that the Q point is the midpoint of (2).

As can be seen from the above, the Q point where the potential is zero exists only on the R side from the midpoint P of the resistor FR, so the load resistance is divided into two equal parts, FQ on the traveling wave output side is a fixed resistor, and the reflected wave output is If the side RQ is a potentiometer, it is possible to directly know the SWR from the position where the potential of the slider terminal of the potentiometer becomes zero. Therefore, if the slider is set in advance at the position of SWR = 8, the Q point will move in the R direction when the SWR is less than S, so the potential of the slider terminal will have the same polarity as E2 and will be zero potential at 8 o'clock, S In the above, since the polarity changes to the same as EB, AL operates only with the polarity of ER.
By removing the C voltage voltage generation circuit membrane, ALC is automatically applied above a predetermined S, and as the swR increases, the A
The LC works to lower the output.

In the case of Figure 3, S is the Q point of zero potential, and ER
is a negative potential, but the configuration is such that the ALC voltage is generated at the output G only when the voltage a applied to the ALC voltage generation circuit membrane force A is (-). As a method for this, configurations that combine various clamp circuits and reverse voltage prevention circuits using diodes (9), transistors, and FET polarity and amplification functions are possible; therefore, the present invention is limited to specific circuits. isn't it.

The problem with the zero point detection method is that all positions on R2 have zero potential when there is no human power. Therefore, in the present invention, in order to avoid malfunctions caused by this, a control threshold setting circuit Y is provided that operates to output the voltage S or reverse the polarity of the output voltage E only when the output voltage E on the traveling wave side is equal to or higher than the set value.
In addition to the control terminal B of the output voltage bfcx of , when EF is below a set threshold value, X is made not to output the ALC voltage.

As a result, even if the SWR is large, unnecessary ALC voltage will not be generated in a small output state that does not cause actual damage to the transmitter, and once the S value and output threshold are set, no need to worry It is possible to secure the transmitter without having to touch it with your hands, and its effectiveness is great.

[Brief explanation of drawings]

FIG. 1 is a conventional example of an ALC voltage generation circuit for a transmitter, FIG. 2 is an example of an ALC voltage generation circuit of the present invention, and FIG. 3 is an explanatory diagram of the operation of the (10) circuit shown in FIG. C...Coupling capacitance, M...Current transformer, Dl
, D2...diode, P,... traveling wave power, PR
... Reflected wave power, y, , EF I EF... Traveling wave side voltage, VR+ #IL HER... Reflected wave side voltage, R1... Fixed resistance, R2... Potentiometer,
X: ALC voltage generation circuit, Y: control threshold setting circuit. Patent applicant Yaesu Musen Co., Ltd. (11) Story 1 1ffi

Claims (1)

[Claims] Transmission power is passed through the primary side, and one output terminal on the secondary side receives a high frequency voltage proportional to the square root of the traveling wave power, and the other output terminal on the secondary side receives a high frequency voltage proportional to the square root of the reflected wave power. Rectifier diodes are connected to both output ends of a CM type directional coupler that generates a high frequency voltage so as to obtain outputs with opposite polarities,
The load resistance connected between the outputs of the diode is divided into two, and the traveling wave output side is a fixed resistance, and the reflected wave output side is a resistance network in which a potentiometer, a meter, or a potentiometer and a fixed resistance are connected in series. The DC voltage generated in direct proportion to the SWR value of the transmission output circuit is applied to the slider terminal to an ALC voltage generation circuit that converts it into an ALC voltage that controls the transmission output, and the output voltage on the traveling wave side of the rectifier diode is applied to the control threshold. the AL through the setting circuit.
A transmitter characterized by having a configuration in which the transmission output is reduced as the SWR value of the transmission output circuit increases by using the operation control input of the C voltage generation circuit, and the ALC voltage is not generated below the set output. ALC circuit.