R.F. Connectors (BNC, Coax, F, N, TNC)

Description | Applications | Pin Assignments | Assembly Instructions

Description

All designed for use with coaxial cable, carrying radio frequency (R.F.) signals. Coax connectors just push together, F connectors are similar but screw together for a more secure connection. N connectors also screw together, and are larger than F connectors. BNC connectors have a bayonet connection - they push together then twist, making them quicker to connect than screw together connectors. TNC connectors are a screw together version of BNC.

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Typical Applications

BNC - Test equipment, video signals, computer networks

Coax - Domestic TV and Radio aerial connections (UHF / VHF)

F - Satellite receivers

N - General R.F. connections

TNC - General R.F. connections

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Pin Assignments

Connections for all the above types of R.F connector are:

Centre Pin: Signal (connect to centre conductor in coaxial cable)

Outer Shield: Ground (connect to screen in coaxial cable)

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Connector Assembly Instructions

Coax (TV / Radio):

See diagram below for exploded view of connector.

1: Unscrew the two parts of the plug and slide the cover (the back part) onto the cable.

2: Twist together the screening and wrap it around the outer insulation. Place the brass 'claws' over the centre conductor, covering the screen.

3: Strip away half the inner insulation to expose the inner conductor. Check that the inner conductor is not touching the screening.

4: Push the centre conductor into the hole in the front half of the plug as far a possible. The centre conductor should show trough the hole from outside, and the brass claws should trap the screen, with the outer insulation underneath. Screw the two halves of the plug together, this will squeeze the brass claws tight on the cable insulation to grip the cable.

5: Cut off the excess wire showing through the centre stem of the plug. To give a really good contact the centre wire should be soldered.

F, N, BNC, TNC:

Most R.F. Connectors are available in 3 fitting assembly types - Solder, Screw-on and Crimp. Crimp connectors are generally neatest, but require a crimping tool. Here's how to fit the other 2 types:

Solder:

1: Disassemble the connector into the parts shown in diagram below.

2: Cut cable to length and prepare end as shown. Be careful not to damage the braided screen or the centre conductor.

3: Slide the nut, washer and grommet onto the cable, then tin the centre conductor and solder the contact pin onto it. Place the top hat over the braid and push it back against the outer cable insulation, then pull the braid back over it.

4: Insert all the parts into the connector body and tighten the hex nut, using a spanner if necessary. This compresses the cable gland and secures the connector.

Screw-on:

See diagram below for exploded view of assembly.

1: Strip about 15mm of outer insulation from the cable. Twist together the screening and wind it around the outer insulation.

2: Strip half of the inner insulation to expose the centre conductor. Check this wire is not touching the screen.

3: Feed the centre conductor into the connector and screw the connector clockwise (viewed from the plug side) until tight.

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