JPH0623067Y2 - Transmitter output amplifier protection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a transmitter output amplification for preventing destruction due to thermal runaway when the output amplification element in a wireless transmitter rises above a specified temperature. The present invention relates to a device protection device.

[Conventional technology]

The output amplification section of the conventional wireless transmitter uses an output amplification element such as an electron tube or a semiconductor for the purpose of power amplification, but the difference between the input power and the output power of this output amplification element causes internal loss. As a result of heating the output amplification element, the temperature of the output amplification element is raised to the balance point between this heating and heat dissipation. In particular, semiconductor devices are generally susceptible to temperature increases and their usable temperatures are low, so they are equipped with radiators, and for those with higher power consumption, forced air cooling with a cooling fan reduces the device temperature. Is measuring.

On the other hand, in the case of the electron tube, the usable temperature is higher than that of the semiconductor, but since the rise in the temperature inside the electron tube affects the life, the cooling fan is often used for medium power or more.

In addition, even if there is no special failure in the equipment, the output amplification element may rise in temperature more than the allowable value due to long-term continuous use, increase in ambient temperature, increase in power supply voltage or failure of cooling fan. Therefore, when the temperature of the output amplification element is monitored, and if it rises above a specified value, measures are taken to prevent the destruction of the output amplification element by stopping the operation of the equipment by means such as cutting off the power supply. Was there.

[Problems to be solved by the device]

However, in the conventional technique as described above, although the purpose of protecting the output amplifying element can be achieved, the communication is interrupted by suddenly turning off the power supply, which causes confusion to the receiver. In addition, in a semiconductor element having a large difference in temperature response, the cooling fan is always operating and mechanical or electrical noise is generated even though there is almost no heat generation during reception or low power transmission. This consumes useless power, which is disadvantageous to the operator.

The present invention has been made for the purpose of remedying the above-mentioned drawbacks of the conventionally known protection devices.

[Means for Solving the Problems]

Therefore, the present invention sets the detection range of the temperature rise in the output amplification element (31) in two stages by the temperature sensitive elements (41) and (42),
When the maximum power is transmitted, the cooling fan (6) is operated when the temperature becomes equal to or higher than the preset first temperature, and the transmission is further continued or the preset first temperature is set by another cause. When the temperature is higher than the second temperature which is higher than the temperature of, the power consumption of the output amplifying element (31) becomes higher than the transmission output.
It is reduced by the low switching circuit (5), and the output amplification element (3
The temperature rise of 1) is kept within the safe range.

On the other hand, although the transmission output decreases as the supply power decreases, even if there is a decrease in the S / N ratio on the receiving side or an increase in interference, etc. An apparatus for solving the above-mentioned problems of the conventional technology.

〔Example〕

Next, the protection device of the present invention will be described with reference to the drawings.
FIG. 1 is a basic configuration diagram for explaining the present invention. (1) is a front stage section including an original oscillator and a modulator, and (2)
Is an excitation section, (3) is a transmission output amplification section, (31) is an output amplification element, (4) is a temperature sensing element, and (5) is a transmission output high / low switching circuit. Details such as the matching circuit are omitted.

In order to detect and control the temperature of the output amplification element (31) in the transmission output amplification section (3), the temperature sensitive element (4) is closely attached to the surface of the output amplification element (31) or the maximum temperature part of the radiator. In addition, by supplying this output to the transmission output high / low switching circuit (5), thermal runaway of the output amplification element (31) is prevented. In the case of a semiconductor element, the temperature sensitive element (4) may be mechanical (thermostat, etc.), electrical (temperature sensitive resistor, etc.), or magnetic as long as the operating point can be set in the vicinity of 70 ° C to 100 ° C. Any material (such as a temperature-sensitive magnetic material) may be used, and an example thereof will be described later with reference to FIG.

Next, in order to reduce the power of the transmission output amplification unit (3), there is a voltage reduction circuit that reduces the voltage applied to the output amplification element (31) and a current reduction circuit that reduces the current that flows in without changing the voltage. However, the small-sized equipment often employs the current reduction circuit which does not need to change the power supply circuit.

On the other hand, in the transmission output amplifier (3), C in FM mode
Generally, class amplification is performed and class AB amplification is performed in the SSB mode, and it is not desirable to change the bias point. Therefore, the bias of the transmission output amplification section (3) is left unchanged and the excitation section ( By lowering the excitation input to the transmission output amplification unit (3) by controlling 2), the supply current is necessarily reduced, so the output power of the transmission output amplification unit (3) is reduced. It is a thing.

On the other hand, in the amateur communication device, there are not a few devices equipped with output power reduction means for reducing the output power to about 1/10 for short-distance communication in order to save the power supply battery and prevent interference, so the present invention By using the output power reduction means as a circuit for power reduction operation in the output amplification element (31), the application of the present invention can be implemented very easily.

Next, FIG. 2 is a block diagram showing an embodiment of an amateur communication device to which the present invention is applied. The transmission output high / low switching circuit (5) is switched to the low output side, thereby the transmission output amplifying section. The excitation input to (3) is reduced, and the rated output of 50 watts can be reduced to 5 watts, for example. Further, when the temperature sensitive elements (41) and (42) are closely attached to the output amplification element (31) in the transmission output amplification section (3) and the temperature of the output amplification element (31) exceeds, for example, 60 ° C. The temperature element (41) is turned on and the output fan element (31) is cooled by operating the cooling fan (6). Further, when the temperature rises and exceeds, for example, 90 ° C., the temperature sensing element (42) is also turned on and the transmission output is reduced (for example, 50 watts → 5 watts described above). The power consumption of 31) is also greatly reduced and dangerous temperature conditions can be avoided.

Also, if the transmission output high / low switching circuit (5) is set to the low output side, the temperature sensitive element (42) is disabled, but there is almost no temperature rise of the output amplification element (31) in the low output state, and there is no hindrance. There is nothing.

The temperature-sensitive elements (41) and (42) used here are made of a temperature-sensitive magnetic material, and the ferrite magnetic material is a ferromagnetic material at a temperature below the Curie point and a constant temperature above the Curie point. Utilizing the fact that it has the property of becoming a magnetic substance and that the Curie point temperature can be selected near room temperature depending on the composition,
It is a temperature-sensitive magnetic switch.

[Effect of device]

The present invention avoids the dangerous state due to the temperature rise of the output amplification element of the transmission output amplification section, and continuously performs the transmission state without completely stopping it. There is a remarkable effect of not giving.

Furthermore, by using the conventional transmission output reduction circuit,
There is an effect that can be achieved with an extremely simple configuration.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of the present invention, and FIG. 2 is a configuration diagram showing an embodiment of the present invention. 1 ... Front stage, 2 ... Excitation section, 3 ... Transmission output amplification section,
31 ... Output amplification element, 4, 41, 42 ... Temperature sensitive element,
5 …… Transmission output high / low switching circuit, 6 …… Cooling fan.

Claims (1)

[Scope of utility model registration request] 1. A radio transmitter provided with an excitation unit (2) for amplifying an output of a front stage unit (1) and a transmission output amplification unit (3) for power amplification of an output from the excitation unit (2), wherein the transmission is performed. First temperature sensitive element (41) for detecting the temperature of the output amplification element (31) of the output amplification section (3)
Means for operating the cooling fan (6) when a temperature equal to or higher than the preset first temperature is detected, and the output amplification element
When the second temperature sensitive element (42) for detecting the temperature of (31) detects a second temperature or higher higher than the preset first temperature, the transmission output high / low switching circuit (5) is activated. A transmitter output amplifying element characterized by comprising means for reducing the power consumption of the transmission output amplifying section (3) by switching to a low output side and reducing the excitation output of the exciting section (2). Protector.