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If the windows are cut to the sizes suggested you will be able to use one piece of Maplin red filter material for both cases. Contrary to the information in the Maplin/MPS catalogue, this material cannot be cut with scissors as it will crack. Use a junior hacksaw.

RS supply polarised red filter material which is darker and can be cut with scissors. This gives a more pleasing appearance than the Maplin material, but may be more difficult to obtain.

Interwiring
The interwiring is very straight-forward. The transformer secondary wires are connected to the veropins in the T1 position on the PCB, with the black wire to the centre pin and the two red wires (either way round) to the other two. The brown and blue primary wires are connected to the incoming mains cable with a 2-way piece of choc-block connector mounted in the case. Brown to brown, and blue to blue.

The coax sockets are connected to the relevant pins on the pcb using suitable coaxial cable. Cheap audio cable was used in the prototype and worked successfully, but the type specified in the parts list would be more suitable. The outer of each socket is connected via the screen of the cable to the relevant pin closest to the end of the PCB, while the core of the cable is used to connect the centre pin of the socket to the other pin on the PCB. Be sure to mark the sockets "LINK", "TV" and "VIDEO", in accordance with the circuit diagram.

Testing
No setting up is required, testing merely involves connecting the two sections and seeing if they work! When testing, ensure that the light from the transmitter does not shine directly on the receiver, or feedback may cause odd results.

Connect the two sections with a good length coaxial aerial cable between the "LINK" sockets (SK1 and SK3). Alternatively a length of two-core cable may be used; this may be soldered directly to the pins on the PCB's for convenience.

Connect the transmitter section to the mains and position it such that it is pointing at a video recorder, from about 2 metres away. Take the receiver and the video's remote control into another room, and try using the remote control about 2 metres from the receiver.

When the remote control is operated, the red LEDs on the receiver and transmitter should flash. If the channel change buttons are operated, the corresponding changes should be heard from the TV in the other room.

Fault Finding
If the unit does not work, there are a few points to check before embarking on a full faultfinding procedure.

First check the power supply voltages. There should be about 18V across C6 and C7, and around 12V at SK2. The power supply rail in the receiver (across D2) should be 5V.

Check that the LEDs are the right way round. The details in catalogues and data sheets can be confusing when it comes to identifying the polarity of LEDs, and different manufacturers use different arrangements. The PCB overlay is correct for the devices supplied by Maplin.

Check the aerial fly-leads for continuity, and short circuits. One of the two purchased by the author for these units was found to be open-circuit on the centre core!

If all this checks out, it's down to good old fashioned fault finding procedures. The circuit is not complicated so this should not take too long.