Cable Attachment Methods

There are several methods used to attach coaxial cable to a connector. Johnson Components, Inc. manufactures connectors for flexible and semi-rigid coaxial cable which are attached to the cable via crimping, clamping or soldering. The method terminology refers to the attachment of the cable braid or shield to the connector body. The following information describes general attachment methods used for flexible and semi-rigicl cable. Most examples are shown with SMA interfaces, but the methods apply to all connectors. For more detailed instructions for specific connectors, please refer to the assembly instructions in the Johnson Components, Inc. RF Coaxial Connector catalog.

Flexible Cable:

Crimp

The crimp attachment method provides the most consistent electrical and mechanical performance for flexible cabled connectors. This method is most preferred in manufacturing environments since the attachment can be made in the least amount of time with the greatest reliability. If well designed crimping tools are used, the attachment will be made consistently every time. The disadvantage of crimping is that the connector car, not be re-used if reattachment is necessary.

Upon assembly, the connector's center conductor is either soldered or crimped to the center conductor of the cable. The braid of the cable is then flared and the connector's crimp stem is slid under the braid. A sleeve is then crimped over the braid, completing the attachment. This general method applies to connectors with non-captivated and some captivated contacts. The exceptions are the SMB/SMC crosshole type connectors, as seen below.

The crosshole assembly has a captivated contact. The cable attachment method for these types of connectors requires that the stripped cable be fecl into the connector before the center contact is either crimped or solclered to the cable via the access port.

Clamp

The clamp attachment is preferred in field installations since special tools are not required to make the attachment. This method can be very reliable if the clamp nut is tightened to the specified torque. The advantage of clamping is that the connector can be re-used if reattachment is necessary. Clamping is not preferred in a manufacturing environment because of the extra time needed to make the attachment.

Upon assembly, braid of the cable is flared and the connector's clamp stem is slid under the braid. The connector's center conductor is then either soldered or crimped to the center conductor of the cable. A clamp cone then slides over the braid/stem assembly and the clamp nut attaches this completed assembly to the connector body. Although torque wrenches are not required to complete the attachment, the nut should be tightened to the specified assembly torque for optimum mechanical and electrical performance.

Semi-rigid Cable:

Solder

All semi-rigid cabled connectors which Johnson Components, Inc. currently manufactures are soldered to the cable's outer shield. The solder joint between the cable shield and the connector body must be complete and free of voids for optimum performance. Several methods are used to attach the cable center conductor to the connector's center contact. The best electrical performance in a semi-rigid SMA plug connector is gained by using the center conductor of the cable as the connector's center contact, as seen below.

The center conductor of the cable is pointed before the shield is soldered to the connector body. The use of this type of connector ensures the best possible electrical performance since there are no impedance changes present due to a separate contact. This type of connector is best used in applications which do not require frequent mating cycles. The pointed conductor may tend to remove the plating and the base metal in the mating female conductor if the connectors are subject to many mating cycles.

Semi-rigid connectors with center conductors are attached to the cable much in the same fashion as are flexible cabled connectors. The main difference is that the cable's outer conductor is a solid tube instead of a braid. Although other manufacturers offer semi-rigicl clamp or crimp attachment, Johnson Components, Inc. only offers solder types at the present time.