In sequence, from hfkits:

• large Ferrite toroid, for example an FT240-43,
• copper wire,
• plastic case,
• PL-259 antenna socket also known as an SO-239

We chose to build an unun with a ferrite toroid choke with bisectional bifilar windings which, in essence, is just a way of describing the type of stitching around the toroid core. Firstly, it is a good idea to use a plastic box for the project, obviously, because there should be no contact between the antenna sockets, either on the grounding or on the signal made through the box itself - for example, if the box were metal, and the ground between the entry and exit were connected via the metal box, then the unun would just be skipped by the current and the current would just travel over the metal box. In this situation in particular, due to no plastic box available, a metal box was used so extra care had to be taken to isolate the sockets from each other in order to make sure that they are not connected via the metal within the box.

For example, the SO-239 sockets are first taped with painters tape and the rest is painted over in order to isolate the socket and reduce the likelihood that it touches the metal box. The sockets are then mounted into the metal box and the toroid is prepared to be wrapped.

Some wire is salvaged from a kettle cable and then connected to one of the sockets, with the two sides of the braiding left out and prepared to be wrapped around the ferrite core.

The braiding consists in 11 or 12 wraps around the ferrite core on the left and symmetrically the same on the right, up until the other socket is reached where the cables are soldered onto the SO-239 socket in order to complete the project.

The project is then completed and placed inside the metal case whilst making sure to not make contact between the SO-239 sockets and the antenna.