JPH0416941Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention relates to an improvement of a direct reading type VSWR meter circuit.

[Conventional technology]

Figure 2 shows a circuit example of a conventional direct reading VSWR meter.The output power from the transmitter is connected to a directional coupler.
The traveling wave output voltage Vf obtained by detecting DC and rectifying it with a detector D ₁ and the reflected power from a load (antenna, etc.) are detected with a directional coupler DC, and then the detector
The reflected wave output voltage Vr obtained by rectifying D ₂ and the meter M ₁
and M ₂ (sometimes reading by switching one instrument), and calibrated using the relational formula: Vf + Vr / Vf - Vr = VSWR (standing wave ratio), so that VSWR can be read directly. be.

[The problem that the idea attempts to solve]

However, in the conventional technology described above, in order to read the same direct reading scale even when the traveling wave power changes, it is necessary to change the sensitivity of M ₁ and M ₂ at the same time, so the variable resistors VR ₁ and VR ₂ are used. Normally, the VSWR of the traveling wave output meter _M2 is read on the direct reading scale when the scale of the traveling wave output meter _M1 indicates the maximum. In addition, a correction variable resistor Vr is also provided, which has a complicated structure and operation and is disadvantageous in terms of cost.

In view of the above-mentioned problems, this invention improves the processing circuit for the traveling wave output voltage Vf and the reflected wave output voltage Vr,
The goal is to eliminate the need for sensitivity adjustment using interlocking variable resistors and to enable direct reading of VSWR using a single meter.

[Means to solve the problem]

This invention uses a directional coupler inserted between the transmitter output section and the load to reduce the traveling wave output voltage Vf.
By detecting the reflected wave output voltage Vr and using the relational expression Vf + Vr / Vf - Vr = VSWR (standing wave ratio), the traveling wave output voltage can be semi-fixed using a direct reading measuring instrument with a calibrated standing wave ratio scale. In addition to the base of the transistor, the reflected wave output voltage is applied to the collector of the transistor, and the voltage is applied between the collector and ground of the transistor.
The VSWR direct-reading DC ammeter is connected to a variable resistor for direct-reading scale calibration, and _a series feedback resistor is connected to the emitter of the _transistor . Direct reading type that allows direct reading without adjustment by adjusting to a wide range of transmitter power.
It is a VSWR meter.

〔Example〕

FIG. 1 shows an embodiment of the present invention. The directional coupler DC and the detectors D ₁ and D ₂ are completely the same as in FIG. 2. The feature of this invention is that the traveling wave output voltage is resistance
A configuration in which the voltage is semi-fixedly divided by R ₁ and a semi-fixed resistor R ₂ and applied to the base of a transistor Q which has a feedback resistor R ₄ in series with the emitter, and the reflected wave output voltage is passed through a resistor R ₃ to the transistor Q's base. In addition to the collector, a DC ammeter M for direct reading of VSWR and a semi-fixed resistor R for direct reading scale calibration are installed between the collector and earth _.
It is a direct reading type VSWR meter _{consisting of} a configuration with It is possible to read it directly.

Figure 3 shows the direct reading VSWR meter of the present invention connected between a transmitter with a rated impedance of 50Ω and a load resistor.
Load resistance is 75Ω (VSWR=1.5 condition) and 100Ω
This is an example of reading the VSWR indication of the meter when changing the transmitter output with (VSWR = 2 state),
It can be seen that a constant indication can be obtained in the range of approximately 10W to 100W or more. In order to obtain a constant indication over such a wide range, it is important to appropriately select the feedback resistor _R4 connected in series with the emitter of the transistor.

Figure 4 shows the tendency based on experimental examples when the value of _R4 is changed.If the feedback resistor _R4 is not included, as in A, when the input voltage of the base exceeds the threshold level of the transistor, the meter The instruction of M decreases once rapidly and then gradually increases. If the feedback resistance R ₄ is smaller than the appropriate value, the region shown in B, which exceeds the threshold level, will have a medium-double shape. Furthermore, if the feedback resistance _R4 is too large, the indication tends to gradually increase as shown in C. D is when _R4 is set to an appropriate value, and it is possible to obtain certain instructions over a fairly wide range above the threshold level. Note that by setting the measurable range above the threshold level, it is possible to obtain certain instructions over a fairly wide range. If you want to extend the measurable range to below the threshold level, you can apply a slight bias voltage to the base of Q in advance, or apply 57−42964)
Application of the technology disclosed in "SWR meter circuit" is effective. Furthermore, by adding a "peak indicating circuit" to the Q collector circuit as shown in FIG. 5, it is possible to directly read the VSWR during SSB transmission.

[Effect of idea]

It is clear from the above experimental results that the circuit configuration of the present invention has a sufficient practical effect, and the effect is extremely large in terms of economic efficiency in commercialization and practical convenience.

[Brief explanation of drawings]

Figure 1 shows an example of the configuration of a general VSWR meter.
The figure shows an example of the configuration of the direct-reading VSWR meter of the present invention.
The figure shows an actual measurement example of the indicating characteristic, FIG. 4 is a curve diagram for explaining the influence of the feedback resistance value on the indicating characteristic, and FIG. 5 is a circuit diagram that can be measured even during SSB transmission. DC...Directional coupler, _R1 , _R3 , _R4 ...Resistor, _R2 , _R5 ...Semi-fixed resistor, M...DC ammeter, Q...Transistor.

Claims (1)

[Scope of utility model registration request] A directional coupler inserted between the transmitter output section and the load reduces the traveling wave output voltage by half in a direct reading measuring device with a standing wave ratio scale that detects the traveling wave output voltage and the reflected wave output voltage. Fixedly divided, in addition to the base of the transistor, the reflected wave output voltage is applied to the collector of the transistor, and a calibration resistor and direct reading type are used to detect the VSWR from the collector voltage between the collector and ground of the transistor.
A direct-reading VSWR meter, characterized in that a VSWR meter is connected to the emitter of the transistor, and a series feedback resistor is connected to the emitter of the transistor, the resistance value of which prevents the collector voltage from dropping when the threshold is exceeded.