Low noise down converter

Abstract

The utility model discloses a low-noise down converter, which belongs to the technical field of satellite communication equipment and comprises a base, a radio frequency connector, a flange plate, a circuit board assembly, a sealing seat and a sealing plate. The radio frequency connector is arranged on the base, the flange plate is arranged on the base, the base is provided with an installation groove, the circuit board assembly is installed in the installation groove, the sealing seat is provided with a sealing groove, and the sealing seat is installed in the installation groove and arranged on the circuit board assembly in a sleeved mode through the sealing groove. A first dispensing groove is formed between the sealing seat and the inner wall of the mounting groove, and the sealing plate is mounted on the base and covers a groove opening of the mounting groove. The low-noise down converter provided by the utility model can improve the dustproof and waterproof performance.

Description

Technical Field

[0001] The utility model relates to the technical field of satellite communication equipment, in particular to a low-noise downconverter. Background Art

[0002] An LNB, also known as a Low Noise Block (LNB), is a low-noise downconverter. Its function is to amplify and downconvert the satellite signal transmitted by the feed, convert the Ku or C-band signal into the L-band, and transmit it to the satellite receiver through a coaxial cable. With the development of satellite communication equipment, more and more low-noise downconverters are integrated into satellite communication portable stations and ultra-thin satellite antennas to meet the requirements of more and more application fields such as communication, monitoring, and remote sensing. At present, after the circuit board assembly in the low-noise downconverter is installed in the base or the casing, the cover is installed by bolts to achieve sealing. After long-term use, the bolts are prone to looseness, and dust and water are likely to enter the base through the gap between the cover and the base, resulting in poor dust and water protection performance. Summary of the Utility Model

[0003] The purpose of the embodiment of the utility model is to provide a low-noise downconverter, which can improve the dust and water protection performance.

[0004] To achieve the above purpose, the utility model adopts the following technical solutions:

[0005] A low-noise downconverter, comprising:

[0006] A base with an installation groove;

[0007] A radio frequency connector provided on the base;

[0008] A flange provided on the base;

[0009] A circuit board assembly installed in the installation groove;

[0010] A sealing seat installed in the installation groove and covering the circuit board assembly;

[0011] And

[0012] A sealing plate;

[0013] The sealing plate is installed on the base and covers the notch of the installation groove.

[0014] Optionally, the base has a first outer side and a second outer side, the first outer side and the second outer side face away from each other, the radio frequency connector is an SSMA connector and is installed on the first outer side of the base through a first bolt, and the flange is a flat flange and is integrally formed with the base.

[0015] Optionally, the low-noise downconverter further includes a waterproof ring; the base has a first sealing surface, the sealing plate has a second sealing surface, the second sealing surface abuts against the first sealing surface, and the waterproof ring is clamped between the second sealing surface and the first sealing surface.

[0016] Optionally, the first sealing surface is provided with a first sealing ring groove, the first sealing ring groove extends along the edge of the installation groove and is disposed around the installation groove, at least part of the waterproof ring is clamped in the first sealing ring groove, and the second sealing surface is connected to the first sealing surface in abutting connection through a colloid.

[0017] Optionally, both the first sealing surface and the second sealing surface are provided with nickel-tin layers, and the second sealing surface is connected to the first sealing surface through reflow soldering.

[0018] Optionally, the materials of the base, the flange plate, and the sealing plate are all aluminum-lithium alloy, or titanium-aluminum alloy, or magnesium alloy, or beryllium alloy, or titanium alloy.

[0019] Optionally, the low-noise downconverter further includes a first cover with a threaded groove and a second cover with a sleeve groove; the RF connector has a first connection channel communicating with the installation groove, an external thread is provided on the RF connector and disposed outside the first connection channel in a circumferential manner, the flange plate has a second connection channel communicating with the installation groove, a plug body is provided on the bottom wall of the threaded groove, the first cover is sleeved on the RF connector through the threaded groove and is threadedly connected to the RF connector, the plug body is inserted into the first connection channel, and the second cover is sleeved on the flange plate through the sleeve groove and covers the opening of the second connection channel.

[0020] Optionally, the low-noise downconverter further includes a sealing ring; a second sealing ring groove and a plurality of first threaded holes are formed on the flange plate, the second sealing ring groove extends circumferentially along the second connection channel, and the plurality of first threaded holes are located in the area enclosed by the second sealing ring groove and are disposed at intervals along the circumferential direction of the second connection channel.

[0021] Optionally, the low-noise downconverter further includes a slip ring with a second threaded hole; the sealing ring is installed on the slip ring, the second threaded hole communicates with the first threaded hole, and there are a plurality of second threaded holes corresponding to the plurality of first threaded holes one by one;

[0022] The slip ring is slidably disposed in the second sealing ring groove along the axis direction of the first threaded hole, the sealing ring has an abutting portion and a sealing portion, the second sealing ring groove has a limiting inner wall located on the moving path of the abutting portion, and when the abutting portion abuts against the limiting inner wall, the sealing portion extends out of the second sealing ring groove.

[0023] Optionally, the inner wall of the installation groove is lined with sound-absorbing boards and / or sound-absorbing cotton.

[0024] The beneficial effects of the present utility model are as follows:

[0025] The low-noise down-converter of the present utility model uses a sealing seat. First, the sealing groove of the sealing seat is sleeved on the circuit board assembly, and then sealant is dot-coated on the dispensing groove formed between the sealing seat and the base by using dispensing technology to achieve the sealing of the circuit board assembly. Finally, the installation groove opening is covered by installing a sealing plate to prevent the colloid in the dispensing groove from being eroded due to exposure. The sealing seat, dispensing of sealant, and sealing plate are used together to improve the dust and water protection performance of the low-noise down-converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The following further describes the present utility model in detail with reference to the drawings and embodiments.

[0027] Figure 1 is a schematic structural diagram of the low-noise down-converter;

[0028] Figure 2 is Figure 1 an exploded view of

[0029] Figure 3 is Figure 1 a sectional view of

[0030] Figure 4 is a schematic structural diagram of the first protective cover, the second protective cover, the base, the RF connector, and the flange;

[0031] Figure 5 is a schematic structural diagram of the sealing ring, the slip ring, and the flange;

[0032] Figure 6 is a partial sectional view when the sealing ring, the slip ring, and the flange are fitted together.

[0033] Explanation of reference numerals in the drawings: In the figures:

[0034] 11. Base; 12. RF connector; 13. Flange; 14. Circuit board assembly; 15. Sealing seat; 16. Sealing plate; 17. Screw; 18. First protective cover; 19. Second protective cover; 20. Sealing ring; 21. Slip ring; 22. Bolt; 23. First dispensing groove;

[0035] 111. Installation groove; 112. First outer side; 113. First sealing surface; 114. First sealing ring groove;

[0036] 121. First connection channel; 122. External thread;

[0037] 131. Second connection channel; 132. First threaded hole; 133. Second sealing ring groove; 134. Limiting inner wall;

[0038] 151. Sealing groove

[0039] 161. Second sealing surface

[0040] 181. Threaded groove; 182. Plug body

[0041] 191. Sleeve groove; 192. Third threaded hole

[0042] 201. Abutting portion; 202. Sealing portion

[0043] 211. Second threaded hole Detailed implementation manner

[0044] To make the technical problems solved by the present utility model, the technical solutions adopted and the achieved technical effects clearer, the technical solutions of the embodiments of the present utility model will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative efforts fall within the protection scope of the present utility model.

[0045] In the description of the present utility model, unless otherwise clearly defined and limited, the terms "connected", "fixed", "connected", "communicated", "abutted", "clamped", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific situations.

[0046] In the present utility model, unless otherwise clearly defined and limited, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features between them. Moreover, the first feature being "above", "above" and "on the top" of the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "below", "below" and "under the bottom" of the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is lower than that of the second feature.

[0047] In the description of this article, it should be understood that the orientation or positional relationships such as "upper", "lower", "left", "right", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of description and simplifying operations, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation to the present utility model. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0048] In the description of this specification, the descriptions referring to terms such as "one embodiment", "example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present utility model. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example.

[0049] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0050] Unless otherwise specified or defined, the term "and / or" used in the present utility model includes any and all combinations of one or more of the related listed items.

[0051] For the convenience of narration, unless otherwise stated, the up and down directions mentioned below are the same as the up and down directions of Figure 3 itself, and the left and right directions mentioned below are the same as the left and right directions of Figure 3 itself.

[0052] The low-noise downconverter of this application is mainly applied to devices such as satellite portable stations and ultra-thin antennas. The low-noise downconverter can be integrated and used in communication portable stations and ultra-thin satellite antennas.

[0053] As Figures 1 to 6 shown, a low-noise downconverter includes a base 11, a radio frequency connector 12, a flange 13, a circuit board assembly 14, a sealing seat 15, and a sealing plate 16. The circuit board assembly 14 integrates electronic components such as a low-noise amplifier (LNA), a local oscillator, a mixer, an intermediate frequency amplifier, and a power supply voltage regulator. The radio frequency connector 12 is a radio frequency input port, and the flange 13 is an intermediate frequency input port. The radio frequency connector 12 is provided on the base 11, and the flange 13 is provided on the base 11. The radio frequency connector 12 and the flange 13 are respectively installed on the outer side surface of the base 11 and are located on the left and right sides of the base 11.

[0054] The base 11 has a mounting groove 111 which is opened on the upper end surface of the base 11. The mounting groove 111 is used to accommodate the circuit board assembly 14 and the sealing seat 15. The circuit board assembly 14 is installed in the mounting groove 111. The sealing seat 15 has a sealing groove 151 which is opened on the lower end surface of the sealing seat 15. The sealing seat 15 is installed in the mounting groove 111 and sleeved on the circuit board assembly 14 through the sealing groove 151, and the circuit board assembly 14 can be sealed in the space formed by the enclosure of the sealing seat 15 and the bottom wall of the mounting groove 111. After the sealing seat 15 is installed in the mounting groove 111, a first glue dispensing groove 23 is formed between the periphery of the sealing seat 15 and the side wall of the mounting groove 111. The first glue dispensing groove 23 is annularly arranged along the circumference of the sealing seat 15. The sealing glue is filled in the first glue dispensing groove 23 by using the glue dispensing technology to realize the sealing of the circuit board assembly 14. The glue dispensing can be carried out manually or by using glue dispensing equipment. Finally, the sealing plate 16 is installed on the base 11 and covers the notch of the mounting groove 111 to protect the sealing glue and realize the secondary sealing of the circuit board assembly 14, further improving the dust and water protection effect.

[0055] Optionally, a second glue dispensing groove is formed between the sealing seat 15 and the bottom wall of the mounting groove 111. The sealing seat 15 is sequentially connected to the circuit board body of the circuit board assembly 14 and the base 11 through screws 17. A countersunk hole for the screw 17 to pass through is opened on the sealing seat 15. After the head of the screw 17 penetrates into the countersunk hole, the orifice of the countersunk hole is sealed by using the glue dispensing technology to further improve the sealing performance.

[0056] In one embodiment, the base 11 has a first outer side surface 112 and a second outer side surface, the first outer side surface 112 and the second outer side surface face away from each other, the first outer side surface 112 is the left side surface of the base 11, and the second outer side surface is the right side surface of the base 11. The flange 13 is a flat flange and is integrally formed with the base 11. In order to make the overall structure of the low-noise downconverter thin and light so that the entire portable station can be placed in a suitcase or backpack, facilitating single-person carrying and operation. The RF connector 12 in this embodiment is an SSMA connector and is installed on the first outer side surface 112 of the base 11 through the first bolt 22. Compared with the traditional RF input port using a BJ120 standard waveguide connector, the SSMA connector has a smaller volume. Therefore, the volume of the base 11 can be designed to be smaller, making the base 11 thinner and lighter. At the same time, the existing standard mounting flange size is 38.3x38.3mm, the outer side surface of the standard mounting flange is circular, and the standard mounting flange is configured with four mounting screw holes. The large size of the standard mounting flange cannot meet the requirements of the ultra-thin application scenario. This example uses a non-standard flat flange, that is, the upper and lower end surfaces of the flat flange are both horizontal cut surfaces, the flat flange size is 36x20mm, and it is configured with three mounting screw holes. It can not only well adapt to the general interfaces of the current industry, but also greatly reduce the thickness of the input port, thereby reducing the overall thickness of the low-noise downconverter and leaving more available space in the thickness direction for compact portable machines and ultra-thin antennas.

[0057] In this way, by adopting the SSMA connector and the flat flange in this application, the overall thickness of the low-noise downconverter is reduced to less than 10 mm. By filling the sealing glue in the first glue slot 23 formed between the sealing seat 15 and the base 11, the dustproof and waterproof functions are improved.

[0058] In one embodiment, the low-noise downconverter further includes a waterproof ring. The base 11 has a first sealing surface 113, and the first sealing surface 113 is disposed around the mounting groove 111. The sealing plate 16 has a second sealing surface 161, and the second sealing surface 161 is the lower end surface of the sealing plate 16. The second sealing surface 161 abuts against the first sealing surface 113 and the waterproof ring is clamped between the second sealing surface 161 and the first sealing surface 113, further improving the sealing performance of the low-noise downconverter.

[0059] Optionally, the first sealing surface 113 is provided with a first sealing ring groove 114, the first sealing ring groove 114 extends along the edge of the mounting groove 111 and is disposed around the mounting groove 111, and at least part of the waterproof ring is clamped in the first sealing ring groove 114, and the second sealing surface 161 is connected to the first sealing surface 113 by glue.

[0060] Optionally, both the first sealing surface 113 and the second sealing surface 161 are provided with nickel-tin layers, and the second sealing surface 161 is connected to the first sealing surface 113 by reflow soldering, and the reflow soldering technology is used to improve the sealing performance between the sealing plate 16 and the base 11.

[0061] Furthermore, both the sealing plate 16 and the base 11 are made of aluminum alloy, and the first sealing surface 113 and the second sealing surface 161 can also be laser welded to achieve dust-proof and waterproof performance at the airtight level.

[0062] In one embodiment, the materials of the base 11, the flange 13, and the sealing plate 16 are all aluminum-lithium alloy, or titanium-aluminum alloy, or magnesium alloy, or beryllium alloy, or titanium alloy. Aluminum-lithium alloy, titanium-aluminum alloy, magnesium alloy, beryllium alloy, or titanium alloy is light in weight and high in hardness, which can further increase the thickness of the low-noise downconverter, thereby improving the portability of the low-noise downconverter.

[0063] In one embodiment, the low-noise downconverter further includes a first cover 18 having a threaded groove 181 and a second cover 19 having a socket groove 191. The RF connector 12 has a first connection channel 121 communicating with the mounting groove 111. An external thread 122 is provided on the RF connector 12 and is disposed outside the first connection channel 121 in a ring shape. The flange 13 has a second connection channel 131 communicating with the mounting groove 111. A plug body 182 is provided on the bottom wall of the threaded groove 181. The first cover 18 is sleeved on the RF connector 12 through the threaded groove 181 and is threadedly connected to the RF connector 12. The plug body 182 is inserted into the first connection channel 121. The second cover 19 is sleeved on the flange 13 through the socket groove 191 and covers the opening of the second connection channel 131. Since the RF connector 12 has a tube body, the first connection channel 121 is located on the tube body. When the low-noise downconverter is in transportation or being carried, the RF connector 12 is prone to deformation when subjected to external force, and dust, water, etc. are likely to enter the first connection channel 121 and the second connection channel 131. Therefore, in this application, the first cover 18 and the second cover 19 are used to seal the first connection channel 121 and the second connection channel 131 to prevent dust and water from entering the low-noise downconverter before installation. At the same time, by providing the plug body 182 to be snapped into the first connection channel 121, deformation of the RF connector 12 is prevented. A first threaded hole 132 is provided on the flange 13, and a third threaded hole 192 is provided on the second cover 19. The second cover 19 is sleeved on the flange 13 by passing a threaded fastener through the first threaded hole 132 and the third threaded hole 192.

[0064] In one embodiment, the low-noise downconverter further includes a sealing ring 20. The flange 13 is provided with a second sealing ring groove 133 and a plurality of first threaded holes 132. The second sealing ring groove 133 extends circumferentially along the second connection channel 131, and the plurality of first threaded holes 132 are located in the area enclosed by the second sealing ring groove 133 and are arranged at intervals along the circumferential direction of the second connection channel 131. Both the sealing ring 20 and the second sealing ring groove 133 are square rings. By installing the sealing ring 20 in the second sealing ring groove 133, when the flange 13 is connected to the intermediate-frequency input component to achieve intermediate-frequency input, the sealing ring 20 is used to improve the connection tightness between the intermediate-frequency input component and the flange 13.

[0065] In one embodiment, the low-noise downconverter further includes a slip ring 21 having second threaded holes 211. The slip ring 21 is a square ring. The sealing ring 20 is installed on the slip ring 21. At least one of the second threaded holes 211 communicates with one of the first threaded holes 132. When there are multiple second threaded holes 211, it can be that one of the second threaded holes 211 communicates with one of the first threaded holes 132, or it can be that multiple second threaded holes 211 correspond to and communicate with multiple first threaded holes 132 one by one.

[0066] The slip ring 21 is slidably disposed in the second sealing ring groove 133 along the axial direction of the first threaded hole 132. The sealing ring 20 has an abutting portion 201 and a sealing portion 202. The second sealing ring groove 133 has a limiting inner wall 134 located on the moving path of the abutting portion 201. When the abutting portion 201 abuts against the limiting inner wall 134, the sealing portion 202 extends out of the second sealing ring groove 133. When the flange 13 is connected to the intermediate-frequency input component, first pass a threaded fastener through the first threaded hole 132, the second threaded hole 211, and the threaded hole of the intermediate-frequency input component. During the rotation of the threaded fastener, the slip ring 21 slides to the right under the drive of the threaded fastener, so that the abutting portion 201 abuts against the limiting inner wall 134, and the sealing portion 202 moves from inside the second sealing ring groove 133 to outside the second sealing ring groove 133 and abuts against the intermediate-frequency input component to achieve sealing. When disassembling, the threaded fastener rotates in the reverse direction, so that the slip ring 21 drives the sealing ring 20 to be received in the second sealing ring groove 133 to protect the sealing ring 20. The sealing ring 20 is installed on the flange 13 through the slip ring 21. When installing, it is not necessary to additionally install the sealing ring 20 in the second sealing ring groove 133, which is convenient for installation and also avoids the loss of the sealing ring 20.

[0067] It can be understood that the slip ring has elasticity and can be installed in the second sealing ring groove 133 by using the elastic deformation of the slip ring. In other embodiments, the flange 13 can be divided into two detachable seat bodies. One of the seat bodies is integrally formed with the base 11, and the other seat body is detachably connected to the seat body to form the flange 13 and the second sealing ring groove of the flange 13.

[0068] In one embodiment, the inner wall of the installation groove 111 is paved with a sound absorbing board and / or sound absorbing cotton to reduce the noise of the low-noise down converter.

[0069] The technical principle of the present invention is described above in combination with specific embodiments. These descriptions are only for explaining the principle of the present invention and cannot be interpreted as limiting the protection scope of the present invention in any way. Based on the explanations here, technicians in this field can think of other specific implementation methods of the present invention without creative work, and these methods will fall within the protection scope of the present invention.

Claims

1. A low noise down converter, characterized in that: include: A base (11) having a mounting groove (111); A radio frequency connector (12), arranged on the base (11); A flange (13) is provided on the base (11); A circuit board assembly (14) is installed in the installation slot (111); A sealing seat (15) having a sealing groove (151); the sealing seat (15) is installed in the installation groove (111) and sleeved on the circuit board assembly (14) through the sealing groove (151); a first glue dispensing groove (23) is formed between the sealing seat (15) and the inner wall of the installation groove (111); as well as Sealing plate (16); The sealing plate (16) is mounted on the base (11) and covers the notch of the mounting groove (111).

2. The low noise down converter according to claim 1, characterized in that: The base (11) has a first outer side surface (112) and a second outer side surface, the first outer side surface (112) and the second outer side surface are opposite to each other, the radio frequency connector (12) is an SSMA connector and is installed on the first outer side surface (112) of the base (11) by a first bolt (22), and the flange (13) is a flat flange and is integrally formed with the base (11).

3. The low noise down converter according to claim 1, characterized in that: It also includes a waterproof ring; the base (11) has a first sealing surface (113), the sealing plate (16) has a second sealing surface (161), the second sealing surface (161) abuts against the first sealing surface (113), and the waterproof ring is clamped between the second sealing surface (161) and the first sealing surface (113).

4. The low noise down converter according to claim 3, characterized in that: The first sealing surface (113) is provided with a first sealing ring groove (114), the first sealing ring groove (114) extends along the edge of the installation groove (111) and is arranged around the installation groove (111), at least a part of the waterproof ring is clamped in the first sealing ring groove (114), and the second sealing surface (161) is abutted and connected with the first sealing surface (113) through a colloid.

5. The low noise down converter according to claim 3, characterized in that: The first sealing surface (113) and the second sealing surface (161) are both provided with a nickel-tin layer, and the second sealing surface (161) is connected to the first sealing surface (113) by reflow soldering.

6. The low noise down converter according to any one of claims 1 to 5, characterized in that: The materials of the base (11), the flange (13) and the sealing plate (16) are all aluminum-lithium alloy, titanium-aluminum alloy, magnesium alloy, beryllium alloy or titanium alloy.

7. The low noise down converter according to any one of claims 1 to 5, characterized in that: The invention also comprises a first protective cover (18) having a thread groove (181) and a second protective cover (19) having a sleeve groove (191); the radio frequency connector (12) has a first connecting channel (121) communicating with the mounting groove (111); the radio frequency connector (12) is provided with an external thread (122) arranged around the outer side of the first connecting channel (121); the flange (13) has a second connecting channel (131) communicating with the mounting groove (111); a plug body (182) is provided on the bottom wall of the thread groove (181); the first protective cover (18) is sleeved on the radio frequency connector (12) through the thread groove (181) and is threadedly connected to the radio frequency connector (12); the plug body (182) is inserted into the first connecting channel (121); the second protective cover (19) is sleeved on the flange (13) through the sleeve groove (191) and covers the opening of the second connecting channel (131).

8. The low noise down converter according to claim 7, characterized in that: It also includes a sealing ring (20); a second sealing ring groove (133) and a plurality of first threaded holes (132) are provided on the flange (13); the second sealing ring groove (133) extends circumferentially along the second connecting channel (131); the plurality of first threaded holes (132) are located in an area enclosed by the second sealing ring groove (133) and are arranged at intervals along the circumference of the second connecting channel (131).

9. The low noise down converter according to claim 8, characterized in that: It also includes a sliding ring (21) having a second threaded hole (211); the sealing ring (20) is installed on the sliding ring (21); the second threaded hole (211) is connected to the first threaded hole (132); there are a plurality of second threaded holes (211) and they correspond one-to-one to the plurality of first threaded holes (132); The sliding ring (21) is slidably arranged in the second sealing ring groove (133) along the axial direction of the first threaded hole (132); the sealing ring (20) has an abutting portion (201) and a sealing portion (202); the second sealing ring groove (133) has a limiting inner wall (134) located on the moving path of the abutting portion (201); when the abutting portion (201) abuts against the limiting inner wall (134), the sealing portion (202) extends out of the second sealing ring groove (133).

10. The low noise down converter according to any one of claims 1 to 5, characterized in that: The inner wall of the installation groove (111) is paved with a sound absorbing board and / or sound absorbing cotton.

Images