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Building the BCI Filter

Updated: Mar 2

Firstly thanks for purchasing a filter from us. The BCI filter is a high pass filter with a cut off just below the 160m band designed to remove AM and LW broadcast from interfering with your tranceiver, see below.

To build

The fist thing to do is check your the parts in the kit, you should have.


  • 2 x T 68-2 Micrometals Iron Powder Toroid

  • 1.5m of .5mm magnet wire (solderable enamelled copper wire)

  • 1 x TDK RAD 630V 1000pF C0G high quality capacitor

  • 2 x TDK RAD 630V 2200pF C0G high quality capacitor

  • 2 x BNC connectors

The circuit diagram for the build is as follows. There are three capacitors and two inductors in the circuit. The inductors you will need to make up using the Toroids and supplied wire.

The steps to build the kit are.

Solder the BCN connectors to the PCB, these can only go one way round, so it should be clear how they fit.

Then, solder the capacitors to the PCB. You have two 2200pF attached together on a cardboard strip. These get soldered on the left and right of the board, as per the circuit diagrame above. The 1000pF capacitor is soldered in the middle of the board.

Just take the capacitors off the cardboard strip, one at a time. Push the wire through the holes and then solder them from the back of the PCB.

Cut your wire in half, the supplied wire is more than enough for both toroids, so you should have some spare.

To make the inductors you will need to wind wire around the toroids. They are both setup the same with 22 turns. One turn is when the wire passes through the middle of the toroid. See image below this one has 24 turns, but you will get the idea.

Cut the wire so its long enough to go through the hole and out the back side of the board, see above. Take the toroid off the board and then strip the insulation off. Then place the toroid back onto the board with the wire going through the holdes then solder in place.

When you solder to toroids onto the board, place them away from each other as per the picture below.

To tidy up trim any remaining wire from the capacitors and inductors (toroids) from the back of the PCB with wire snips.

That should be it.

If you have purchased a bare kit you can download and 3D print a case from here

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