JPH08222951A - Local oscillation circuit - Google Patents

Abstract

PURPOSE: To provide the local oscillation circuit able to adjust an oscillating frequency with high accuracy through a simple configuration applied to a BS converter or the like. CONSTITUTION: A printed circuit board 107 is placed on a chassis 105 made of a die-cast or the like and a shield case 103 made of a sheet metal or the like is soldered to a copper foil 107a with a solder piece 104. A support base 102 and a dielectric resonator 101 are mounted on the printed circuit board 107, a hole is made to a part of the shield case 103 corresponding to the dielectric resonator 101, a screw hole is made to a part of the chassis 105 corresponding to the shield case 103 and a screw 106 is inserted to the hole. Through the constitution above, when the screw 106 is screwed in, the distance between the screw 106 and the dielectric resonator 101 is reduced, then the resonance frequency gets higher and when the distance is increased, the resonance frequency gets lower. The resonance frequency of the local oscillation circuit is adjusted by turning the screw 106 as above.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a local oscillator circuit used in a BS converter or the like, which stabilizes the oscillation frequency by using a dielectric resonator.

[0002]

2. Description of the Related Art FIG. 2 shows a configuration example of a local oscillation circuit using a conventional dielectric resonance circuit. A circuit board 207 is placed on a chassis 208 made of die casting or the like, and a copper case 207a is provided with a shield case 203 made of a sheet metal or the like.
Are soldered with solder 204. A support 202 and a dielectric resonator 201 are mounted on the circuit board 207,
A driving nut 205 is driven and a screw 206 is inserted into a hole formed in a portion of the shield case 203 corresponding to the dielectric resonator 201. With such a configuration, the screw 206 is screwed into the dielectric resonator 201.
The resonance frequency becomes high when the distance between and is small, and the resonance frequency becomes low when the distance is large. By rotating the screw 206 in this way, the resonance frequency of the local oscillation circuit can be adjusted. However, like this, the shield case 203
If a sheet metal is used, a driving nut 205 that has been threaded in advance is used to attach the screw 206, or the sheet metal is thickened to directly screw the sheet metal, or a double nut is used to fix the screw. Since it is necessary, there is a problem that the configuration becomes complicated and workability is poor.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object thereof is to provide a local oscillation circuit having a simple structure and capable of adjusting the oscillation frequency with high accuracy.

[0004]

SOLUTION: A hole is made in a corresponding portion of a dielectric resonator of a sheet metal shield case covering a local oscillator, and a screw is provided at a corresponding position of a chassis for mounting a circuit board. The oscillation frequency is adjusted according to the distance between the resonators. The chassis is die cast.

[0005]

[Operation] A hole is made in a corresponding portion of the dielectric resonator of the sheet metal shield case that covers the local oscillator, a screw is provided at a corresponding position of the chassis for mounting the circuit board, and the distance between the screw and the dielectric resonator is provided. By adjusting the oscillating frequency with, the screw can be attached to a material having a plate thickness such as die-cast, so that the frequency can be stably adjusted with a simple structure.

[0006]

EXAMPLE A local oscillator circuit according to the present invention will be described below.
This will be described in detail with reference to the drawings. FIG. 1 is a block diagram of an embodiment of a local oscillator circuit according to the present invention. A circuit board 107 is placed on a chassis 105 made of die-cast or the like, and a shield case 103 made of sheet metal or the like is soldered to the copper board 107a with solder 104. Circuit board 1
A support base 102 and a dielectric resonator 101 are mounted on 07, and the dielectric resonator 101 of the shield case 103 is mounted.
A hole is formed in a portion corresponding to
A screw hole is drilled and a screw 106 is inserted in the corresponding portion of the. With such a configuration, when the screw 106 is screwed in to reduce the distance from the dielectric resonator 101, the resonance frequency becomes higher, and when it becomes larger, the resonance frequency becomes lower. By rotating the screw 106 in this way, the resonance frequency of the local oscillation circuit can be adjusted.

[0007]

According to the present invention, since it is not necessary to thread a sheet metal shield case for a local oscillation circuit, the sheet metal of the shield case can be made thin, and a driving nut or the like is unnecessary. Also, because the adjustment screw is attached to die casting,
Compared to the conventional method of attaching to a sheet metal, the influence of material deformation, distortion, etc. is small and the oscillation frequency becomes stable. Furthermore, waterproofing can be achieved simply by sealing the adjusting screw portion with a silicone adhesive or the like, and a waterproof cover or the like is unnecessary.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of a local oscillator circuit according to the present invention.

FIG. 2 is a configuration diagram of an embodiment of a conventional local oscillation circuit.

[Explanation of symbols]

 101 Dielectric Resonator 102 Support Base 103 Shield Case 104 Solder 105 Chassis 106 Screw 107 Circuit Board 201 Dielectric Resonator 202 Support Base 203 Shield Case 204 Solder 205 Driving Nut 206 Screw 207 Circuit Board

Claims (2)

[Claims] 1. In a local oscillation circuit using a dielectric resonator such as a BS converter, a hole is made in a portion of a shield case of a metal plate covering the local oscillator, the portion corresponding to the dielectric resonator.
A local oscillator characterized in that a screw is provided at a corresponding position of a chassis to which a circuit board is attached, and an oscillation frequency is adjusted by a distance between the screw and the dielectric resonator. 2. The local oscillator according to claim 1, wherein the chassis is die-cast.