JPH0141249Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial field of application> This invention is a preamplifier that is connected between a radio transceiver and an antenna, amplifies radio waves input from the antenna, and supplies the amplified waves to the radio transceiver. Regarding.

<Prior Art> As a conventional preamplifier of this type, there is one shown in FIG. In the figure, 2 is an antenna, and this antenna 2 is connected to a plug 4.
The plug 4 is connected to an arm 8 of a coaxial relay 6.
One contact 10 of this coaxial relay 6 is directly connected to one contact 14 of a coaxial relay 12, and the other contact 16 of the coaxial relay 6 is connected via a high frequency amplification circuit 18 using a gallium arsenide FET. It is connected to the other contact 20 of the coaxial relay 12. Furthermore, the arm 22 of the coaxial relay 12 is connected to a plug 24, and the plug 24 is connected to a wireless transceiver 26.

Further, 28 is a relay control circuit, which is connected to the connection point between the arm 22 and the plug 24, and when it detects a radio wave sent out by the wireless transceiver 26, it activates the coaxial relays 6 and 12. Switching in conjunction, arm 8 becomes contact 10, arm 22 becomes contact 14
If not, the arm 8 is connected to the contact 16 and the arm 22 is connected to the contact 20, respectively.

In a preamplifier with such a configuration, there is a slight time delay between when the relay control device 28 detects a radio wave and when the coaxial relays 6 and 12 actually switch. When switching from the receiving state to the transmitting state, strong radio waves and shock waves sent out from the wireless transmitter/receiver 26 were applied to the high frequency amplifier circuit 18, sometimes damaging the gallium arsenide FET that constitutes it. In order to prevent this, as shown in FIG. 3a, the input side and output side of the high frequency amplifier circuit 18,
Connect PN junction diodes 30 connected in antiparallel to the ground potential point, or connect the output side of the high frequency amplifier circuit 18 to the ground potential point via a high speed relay 32 as shown in FIG. The high-speed relay 32 is driven by the relay control circuit 28 and is closed when the wireless transceiver 26 is in the transmitting state, thereby controlling the high-frequency amplifier circuit 18.
It was necessary to protect the

<Problems to be solved by the invention> However, in such a preamplifier, when a large shock wave is applied, the diode 30 and high-speed relay 32 are damaged and become non-conductive, causing the high-frequency amplification circuit 18 to become non-conductive. There is a problem in that even if the protection is no longer possible, the user is not aware of this and may continue to use the preamplifier and damage the high frequency amplification circuit 18.

<Means for solving the problem> The means for solving the above problem includes a first plug connected to the antenna, two contacts and an arm, and the arm is connected to the first plug. a first relay connected to the first relay, a second relay having two contacts and an arm, one of which is directly connected to one contact of the first relay, and an arm of the second relay. a second plug connected to the wireless transmitter/receiver;
a high frequency amplifier circuit whose input side is connected to the other contact of the second relay; a capacitor connected between the output side of the high frequency amplifier circuit and the other contact of the second relay; and this capacitor and the high frequency amplifier circuit. PIN diode connected between the connection point with the output side of The hands of the normally open switching element connected in series with the power supply terminal and the light emitting element, and the arms of the first and second relays are linked in response to the reception state of the wireless transmitter/receiver, respectively. switching to the other contact and in response to the transmission state of the wireless transceiver, respectively interlocking the arms of the first and second relays to switch to one contact, and supplying an energizing signal to the normally open switching element; It is characterized by comprising a control circuit configured to close this.

<Operation> In the preamplifier configured as described above, when the wireless transmitter/receiver is in the receiving state, the control circuit connects the arms of the first and second relays to their respective other contacts, and No force signal is generated. As a result, the normally open switch element remains open, the light emitting element is turned off, and the PIN diode is also rendered non-conductive.

Therefore, the radio waves input from the antenna are amplified by the high frequency amplification circuit and then input to the radio transceiver.

Next, when the wireless transceiver is set to the transmitting state from this state, the control circuit generates an energizing signal to close the normally open switching element, and connects the power terminal to the light emitting element, the main conductor path of the normally open switching element, and the chain coil. Current flows through the PIN diode, and the PIN diode becomes conductive.

As a result, the output side of the high-frequency amplifier circuit is grounded, and the output of the high-frequency amplifier circuit is generated in a short period of time after the wireless transceiver enters the transmitting state until the first and second relays switch. On the side, strong radio waves and shock waves sent out from a wireless transceiver,
Prevent it from being added.

At the same time, the light emitting element lights up to indicate to the user that the high frequency amplifier circuit is protected from strong radio waves and shock waves.

<Example> An example of this invention will be described below based on FIG. 1. Note that the same parts as in the conventional example are given the same reference numerals, and the description thereof will be omitted.

In FIG. 34 is a capacitor, this capacitor 34 is inserted between the output side of the high frequency amplifier circuit 18 and the contact point 20;
A connection point 36 between 4 and the output side of the high frequency amplification circuit 18
is connected to the ground potential point via the PIN diode 38.

Further, the connection point 36 is connected to the ground potential point via a chiyoke coil 40 and a capacitor 42, and the connection point between the chiyoke coil 40 and the capacitor 42 is connected to a diode 44 and an NPN type transistor 4.
6 emitter and collector, light emitting diode 4
8. Power supply terminal 52 (+
V).

Furthermore, the relay control circuit 28' is connected to the wireless transmitter/receiver 2.
When 6 is in the transmitting state, coaxial relays 6 and 12 are switched in conjunction with each other, an H level energizing signal is generated, and this energizing signal is supplied to the base of transistor 46 via resistor 54.

If the wireless transceiver 26 is now in the receiving state, the relay control circuit 28' will not generate an energizing signal, and therefore the collector-emitter of the transistor 46 will be in a non-conducting state, and the light emitting diode 4 will be in a non-conducting state.
No current flows through either 8 or PIN diode 38,
The PIN diode 38 is brought into a non-conductive state, and the light emitting diode 48 is turned off.

In addition, the relay control circuit 28' connects the arm 8 of the coaxial relay 6 to the contact 16 and the arm 22 of the coaxial relay 12 to the contact 20, so that the radio waves input from the antenna 2 are amplified by the high frequency amplification circuit 18. After that, the signal is input to the wireless transceiver 26.

Next, when the wireless transceiver 26 is placed in the transmitting state, the relay control circuit 28' generates an energizing signal, turns the transistor 46 into a conductive state, and connects the power supply terminal 52 to the power supply terminal 52.
Resistor 50, light emitting diode 48, transistor 4
6 collector and emitter, chiyoke coil 40
Current flows through the PIN diode 38,
The PIN diode 38 becomes conductive, and the output side of the high frequency amplifier circuit 18 is connected to the ground potential point.

As a result, a strong radio wave is transmitted from the wireless transmitter/receiver to the output side of the high frequency amplifier circuit 18 in a short period of time after the wireless transmitter/receiver 26 enters the transmitting state until the coaxial relays 6 and 12 switch. This prevents shock waves from being applied.

At the same time, unless the PIN diode 38 is damaged for some reason, the light emitting diode 48 lights up, indicating that the high frequency amplifier circuit 18 is protected from strong radio waves and shock waves.

Also, in this state, for some reason, the PIN
When the diode 38 is damaged and becomes non-conductive,
The light emitting diode 48 turns off, indicating to the user that the high frequency amplifier circuit 18 is not protected.

<Effects of the invention> As explained above, according to this invention, the high frequency amplifier circuit is activated until the wireless transceiver enters the transmitting state, the PIN diode becomes conductive, and the first and second relays switch. The light emitting diode lights up when it is being protected from strong radio waves and shock waves sent out from the wireless transmitter/receiver circuit, and turns off when the high frequency amplifier circuit can no longer be protected due to damage to the PIN diode, etc. Therefore, the user can see at a glance whether the high-frequency amplifier circuit is protected.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an embodiment based on this invention.
Figure 2 is a circuit diagram of a conventional preamplifier, Figure 3a
3 is a circuit diagram showing an example of a protection circuit of a conventional preamplifier, and FIG. 3b is a circuit diagram showing another example of the protection circuit. 2...Antenna, 4, 24...Plug, 6...Coaxial relay (first), 12...Coaxial relay (second
), 18... High frequency amplifier circuit, 26... Radio transmitter/receiver, 28'... Relay control circuit, 36... Connection point, 38... PIN diode, 40... Chiyoke coil, 46... Transistor (normally open switching element), 48... light emitting diode, 52...
Power terminal.

Claims (1)

[Scope of utility model registration request] a first connector connected to the antenna; a first relay having two contacts and an arm, the arms of which are connected to the first connector; and one relay having two contacts and an arm; a second relay whose contacts are directly connected to one contact of the first relay; a second plug connected to an arm of the second relay to which a wireless transceiver is connected; a high-frequency amplifier circuit whose input side is connected to the other contact of the second relay; a capacitor connected between the output side of the high-frequency amplifier circuit and the other contact of the second relay; and this capacitor and the high-frequency amplifier circuit. A PIN diode connected between the connection point with the output side of the PIN diode and the ground potential point, a chiyoke coil with one end connected to the above connection point, a power supply terminal to which a power supply voltage is applied, and the other end of the chiyoke coil. The main current path and light emitting element of the normally open switching element connected in series with the power supply terminal, and the arms of the first and second relays are linked to each other in response to the reception state of the wireless transceiver. and switching the arms of the first and second relays to one of the contacts in response to the transmission state of the wireless transceiver, respectively, and supplying an energizing signal to the normally open switching element. A preamplifier comprising a control circuit configured to close the circuit.