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Fitting a BNC or TNC connector


50 ohm plug75 ohm plug

Take care to purchase the correct type of BNC plug for your application as there are different models for 50Ω and 75Ω.
On the left is a 50Ω BNC plug. Note the insulation in the center.
On the right is a 75Ω BNC plug. Note there is no insulation in the center.

Other Resources that May Be of Interest:
More Coax Graphics - Auto Antenna Coaxial - Auto Information - Auto Artistry - Auto Coax Industry

I'm showing the method for a BNC plug, the TNC is the same except the locking ring is Threaded instead of Bayonet. There are some minor differences of internal fittings, I'll show the two most common types but the method for all is very similar. stage 1

1. Carefully strip 15mm of the outer insulation.

Slide the gland nut, washer and rubber gasket onto the end of the coax.



stage 2a

2a.With this type:

Trim the outer braid back so that it is level with the outer insulation.

Slide the metal 'top hat' over the dilectric and underneath the braid, it will be a tight fit. The braid and outer insulation will bulge out slightly.

Strip off the dilectric leaving 5mm (dimension 'A') of dilectric between the 'top hat' and the end of the dilectric.

Trim off any excess center conductor, leaving 4mm (dimension 'B') exposed.





stage 2b

2b.With this type:

Slide the metal cone over the exposed braid until it butts up to the outer insulation.

Fold the outer braid back evenly over the cone, trimming off any excess.

Strip off the dilectric leaving 5mm (dimension 'A') of dilectric between the cone and the end of the dilectric.

Trim off any excess center conductor, leaving 4mm (dimension 'B') exposed.



stage 3

3. (Both types) Place the pin onto the center conductor.

Carefully apply a hot slodering iron to the pin and, when heated, apply a small amount of solder through the hole.

There should be no gap between the end of the dilectric and the base of the pin.



stage 4

4. (Both types) Slide the connector body over the pin until the cone or 'top hat' has 'bottomed out' in the casing.

Carefully slide the rubber gasket (this will be tight with the 'top hat' type) and washer down into the casing, followed by the gland nut.

Tighten the gland nut but do not over tighten.

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