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Bredhurst Receiving and Transmitting Society

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Part 2

Practical 7.

Fit a suitable RF connector (PL259, BNC or N-type) to a piece of coaxial cable.

Here the choice is yours as to which type of connector you wish to fit. It is suggested that you make up a patch lead for your amateur radio station.

As removal of the plug after it has been properly fitted often destroys the connector students are likely to be asked to pay a small fee for the connectors and cables if they are not able to readily supply the items from their own stock of part.

This can be a very difficult task for some but other students get the hang of what is required very quickly. Your lead instructor will be on hand to "hint" at where you may be going wrong but is not allowed to help you achieve the end result.

This is the connector that many members of the BRATS club now use. It is a cross between and PL259 and an "N" type in that it connects to a PL259 chassis socket but it has the advantage of the "N" type's water proof rubber grommet and end nut.

You must have the correct size cable for the fitting here is some RG213 for which the  Farnell 724-816 connector is designed, a different connector is needed to fit the thinner cable RG58.

Note the very close weave of the braiding which indicates a good quality cable.

The outer casing has been cut back sufficiently and note that the cut is a nice straight one which has been made using a sharp knife and not "bitten" at by a pair of side cutter which are too small.

Here the braid has been cut back to the outer and the small strands of outer left is quite deliberate.

The next stage it to push the Braid connector under the braid and this is much more easily achieved with the ends of the braid showing.

Here the End nut and the Rubber grommet have been first put on the cable and then the Braid connector has been pushed under the braid causing - correctly - a slight bulge in the outer. The connection between the braid and the braid connector is merely caused by the pressure of the rubber grommet pressing down on the outer when the nut is tightened down. 

The inner insulation has been cut back just proud of the Braid connector and a couple of strands of the centre conductor have been removed to ensure that the conductor will easily pass through the centre of the End barrel.

The centre conductor has now been pushed down and through the End barrel and it is essential to have some of the centre conductor passing through the end so that you can ensure a good solder connection.

All that remains - before making the solder connection is to do several continuity checks.

  • First to check that there is no inner conductor to out braid dead short.
  • Secondly to check that the braid and the centre conductor make an electric connection with respectively the outer case and the centre of the End barrel.

When you are satisfied that all  is well tighten down the nut into the barrel with two correctly fitting spanners.

Then solder up the inner conductor to the centre of the End barrel making sure that you do not allow solder to run down the outside of the centre of the barrel else you will have to file it away to enable the connector to mate properly, without stress, the chassis socket.

Your lead instructor will ensure that you make a good solder joint.

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