hH? - rediffusion


Connecting Yourself to Cable TV

This is the fun bit! Firstly you need to check whether your house was, or is connected to the Rediffusion network; there are three ways you can recognise this:

The box is black ABS plastic. Each of these boxes can feed two subscribers (probably to serve multiple occupancy places) and these are the only type we've seen. The box tops are not screwed on and may simply be unclipped from two clips at the bottom (cable) end of the box.

Open Junction Box

Note at this stage the following information given in Rediffusion's Technical Journal, Vol.1 No.6 (January 1971):-

"VM1-, VM2- and VM4- subscriber inserts are respectively designed to feed a maximum of one, two and four vision subscribers and any attempt to exceed the recommended maximum will result in inferior pictures for the subscribers, especially for the unfortunate subscribers 'paired-up'. If more drop-ins are required it is neccessary to add another junction box."

You may find that the two cables on the bottom of the box have been cut off. This is MultiChannel's way of controlling subscriptions! All you have to do is reconnect them (if this fails, look at the 'Troubleshooting' section later).

You can also see the cables stringing across roads (the ones which don't go from telecom poles), especially up places like Newland Avenue, Cranbrook Avenue, Chanterlands, etc.

If you open a box up you'll find a series of screws, and six pairs of cable. The four we're interested in are the red, yellow, green and white pairs of cables - these are the video ones. Either connect your own cable to them or reconnect the old Rediffusion ones (assuming you've still got your 12-pole channel selector switch mounted).

Wired Junction Box Wired Junction Box

Next thing is to check you're connected. The easiest way to do this is to get a multimeter and check for the presence of an AC current across any pair of cables - if you've got a feeder box then you'll find around 1.5vAC across the line, if you've just got your subscriber connection it'll register around half a volt. Be careful, if you connect two of the different coloured cables together you'll get a potential of around 50vAC, which will hurt!

So now, get your convertor box and wire it up. The old Rediffusion boxes had three cables - MAINS_IN, RF_OUT, and VHF_IN. VHF_IN is usually a two-core copper cable, sometimes it's connected to what looks like an old valve socket (it seems to be some method of controlling the channel actually from the set itself instead of the wall switch). Invariably though it's two core, and these are what goes into VHF_IN. RF_OUT is what goes to your TV, usually by means of coaxial cable (similar to aerial cable), and MAINS_IN you connect up to the nearest mains 240vAC socket. Be careful though, the MAINS_IN is for the white boxes (Rediffusion's own, part number marked on it may be IN109A, this is the one we used), and the circuit here is not for the mains - connect it up to the National Grid and you'll probably get a bit of a fright, at best it'll fry the board, at worst you'll start a fire!

Tune your TV into the VHF signal, and hey presto you've got Sky TV. Best thing to try this on is actually using the Sky Sports channel because that's always got a station identifier in the top left hand corner.

TV wired up and working


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Disclaimer: All the info given here is incomplete, there's always something missing. This is basically to cover our own backs, but for someone with a bit of sense it shouldn't be too hard to fill in the blanks. The authors of this page and the carriers do not take any responsibility whatsoever for any action you may carry out as a result of you reading or using this information. Any documentation provided is given for research purposes only.


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