Assembling clamp type coax connectors

Folk often ask for instructions for assembly of so-called clamp type coax connectors.

This article shows such an N type connector, but the techniques are applicable to different connectors with the same type of cable / braid attachment.

Tools recommended:

  • sharp knife;
  • side cutters;
  • scissors; and
  • soldering iron.

N-clampAbove is a set of parts, from L to R there is:

  1. a gland nut;
  2. a flat washer;
  3. a rubber gland;
  4. a clamp ring;
  5. connector body; and
  6. centre pin.

In some connectors (eg UHF), the centre pin may be captive in the body assembly.

To assemble the connector, slip the nut, washer, and rubber ring onto the cable.

If the clamp ring has a V groove, orient it away from the gland nut.

Trim the cable to expose an appropriate length of dielectric and inner conductor. Trim about 8mm of jacket from the cable and install the clamp ring. The clamp ring often has a recess to receive the end of the cable jacket. If the clamp ring has a V shape to complement the rubber ring, orient it to mate up with the rubber ring. The clamp ring should usually have a rounded over rim over which the braid is now evenly spread. Trim excess braid flush with the outer diameter of the clamp ring using a pair of scissors. It is important that the woven braid is evenly distributed around the clamp ring, do not un-weave the braid.

Check the dielectric trim length and adjust if necessary, Trim the centre conductor as needed. If the centre pin is loose, install it now.

Inspect the prepared cable end and remove any loose ends of wire.

Offer the prepared cable end up to the body taking care to not disturb the braid on the clamp ring. Carefully press it home in the body and insert the rubber ring, washer and nut and using a pari of OE spanners, tighten the gland nut. It is usual that the gland nut is tightened until it bottoms, either by cutting through the V groove type rubber ring, or by bottoming in the thread of the other type of ring.

If the V groove type ring isn't cut, the gland nut has not been sufficiently tightened, it is tightened for a metal on metal clamp of nut, clamp ring, braid to body.

For the other type of rubber ring, tighten the gland nut until it bottoms.

If the gland nut is not sufficiently tight, the cable will pull out in service!

If the centre pin was captive and needs soldering, solder it now.

Test the cable.


Screenshot - 31_03_2014 , 15_29_10

Above is a cross-section of a connector, this one illustrates the V groove type of rubber and clamp rings (very common on BNC). Note where the braid is clamped between the clamp ring and connector body.