Choosing an Unterminated Cable Finish

To use a switching or instrumentation module a cable connection needs to be made to the front panel connector. A connector to unterminated cable allows the user to go from (for example) a D Type connector to a set of individual wires which can be wired to the users need. Pickering Interfaces offers three types of wire finish for these unterminated cables:

• Boot lace ferrules

• Tinned ends

• Cut ends

This page will explain the finish and give some guidance on what to choose.

Boot Lace Ferrules

Two examples of ferrule ends, these use plastic ends at the termination, two styles of marker for the wires shown

Boot lace ferrules are generally the most expensive finish. The wire is stripped and the ends placed in a barrel of a ferrule which is crimped then to secure the ferrule to the wire. If loose markers are used on the wires it helps retain the wire markers (the markers that identify the pin number of the connector at the other end), Pickering Interfaces cable designs use markers which grip the wire.

Tinned Ends

 

Tinned ends on a cable designed around a twisted ribbon cable. The white wire with a black tracer is the drain wire providing a shield connection

Tinned ends strip the insulation at the end of each individual wire, the wires are then tinned so that the individual wires do not fray. It is convenient finish for insertion in terminations requiring soldering but the wires do not need cutting to a custom length. It can be used with screw terminal blocks but on tightening the screw there is little give in the wire and it can be less reliable for this reason if the process is not well controlled.

Tinned ends on individual (not ribbon) wires

The interface between the tinned section of wire and the not tinned wire can be a point of weakness if the cable is not secured with a cable clamp.

Cut Ends

Cut end, users has to strip the wire ends and the jacket

With cut ends the wire is simply cropped and is the cheapest solution to buy, users have to strip insulation on each wire end and connect using their preferred method. It is generally the most flexible though users have the added labour of stripping the insulation from the wire.

This method is very effective when users need to cut wires to a required length, for example when wiring to their own termination strip on a PCB. It is also the most effective finish for use with screw locks used in connector blocks since the copper wire with no solder or ferrule is compressible and the screw is less likely to come loose. On multi-strand wires users have to ensure they handle the individual strands without breakage.

As there are no bare wire ends when the cable is manufactured it may be manufactured as a connector to connector cable, tested and then cut into two halves.