Compared with the outer conductor, the inner conductor with a smaller size and lower strength is more likely to cause poor contact and lead to connector failure. Most of the inner conductors of the connector adopt elastic connection, such as spring claw type elastic connection, socket slotted type elastic connection, bellows-type elastic connection, etc. Among them, the socket slotted elastic connection has the advantages of simple structure, low processing cost, convenient assembly and the most extensive application.
1. The inner conductor is not fixed firmly
In order to assemble, the structure of many micro miniature coaxial connectors is that the inner conductor is divided into two sections by the support of the medium and then connected with the thread. However, due to the small diameter of the inner conductor, the connection strength of the inner conductor is very poor, especially for some small RF coaxial connectors, if the screw connection is not fixed with glue. Therefore, when the connector is connected and disconnected for many times, under the long-term action of torsion and tension, the internal conductor thread may loosen and fall off, leading to connection failure.
One of the common structures of the RF coaxial connector is that the inner conductor, dielectric support and outer conductor are fixed together by adhesive. If the amount of glue applied is not enough or the connection strength of the glue is not enough during the assembly of this structure, the glue applied part may be broken due to the stress during the use, which will cause the inner conductor to rotate or move axially, the inner conductors cannot form good electrical contact, and the connection fails.
Improvement method: when the coaxial connector is assembled, the proper amount of conductive adhesive or thread locking agent can be applied to the threaded connection to increase the reliability of the threaded connection. The adhesive with high bonding strength shall be selected, and the glue shall be filled into the whole glueing hole during glueing; the knurling at the glueing place of the inner conductor shall be increased to increase the contact area between the inner conductor and the adhesive, so as to prevent the inner conductor from rotating; the radial dimensions and tolerances of the inner conductor, the outer conductor and the medium support shall be adjusted properly, so that the fit between the inner conductor and the medium support, the medium support and the outer conductor is interference. Fit also can make the three together more firmly.
2. The size of a socket or pin of the inner conductor is incorrect
If the hole diameter of the conductor in the jack is smaller than the specified size, when the pin of the conductor in the pin enters the jack, it will cause the jack to expand excessively, and the shape variable will exceed its elastic deformation range, resulting in plastic deformation, resulting in damage to the conductor in the jack; on the contrary, if the pin diameter is too small, when the pin and the jack fit, the gap between the pin and the wall of the jack is too large, and the two inside of the connector If the conductor cannot be contacted closely, the contact resistance will increase, and the electrical performance index of the military grade connector will be very poor.
Improvement method: whether the fit of Jack and pin is reasonable or not can be measured by the insertion force and retention force when the standard gauge pin and the conductor in Jack fit. Therefore, we can take the insertion force and retention force as an inspection standard, and adjust the dimensions and tolerances of the jack and the pin, as well as the aging treatment process of the conductor in the jack, so that the insertion force and retention force between the pin and the jack are in a proper range.
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