Using an RF Modulator box


We have a black BT Vision V+ box, and want to watch BT Vision on another TV in another room. We have bought a universal modulator from Maplin, and want to use aerial cable to connect from the BT Vision box to a second TV. We are unable to get this to work.

Submitted online by David Sheridan

What is an RF Modulator?

First things first. The RF modulator is a handy little box that converts a SCART signal into an analogue TV signal that can be sent over a standard aerial cable.

A Modulator is often used to connect to a TV set that has no SCART input socket. They can also be used to send a TV signal from some types of set-top boxes to other rooms in the house. Sky satellite TV boxes have a modulator built-in, as d most old video recorders, and some more expensive digital TV boxes.

The old grey BT Vision boxes had a modulator, but the second generation black boxes didn’t

If you want an RF modulator, we recommend the Universal RF Modulator from Maplin:

The RF Modulator

The Universal Programmable RF Modulator, from Maplin


Connecting the RF Modulator:

First off, make sure you have everything connected correctly. Here’s how you should be connecting:

  1. Connect a SCART lead from the BT Vision box to the SCART input of the RF Modulator box
  2. Find the Aerial RF Out socket on the RF Modulator (May be labelled “To TV”), and plug in an aerial lead that connects to the second TV set
  3. Make sure the other end of the aerial lead is plugged into the second TV correctly.


Rear of Universal RF Modulator

Rear of Universal RF Modulator

Setting the Modulator

Make sure the RF modulator box is powered and working. You also need to set this to an RF channel number – a number between 21 and 68.

In the model we’re discussing, you change channels using the “Function Switches” on the back of the modulator, as per the picture above. See the instructions that came with the modulator if you’re not sure of how to change the channel number to a free channel.

Tuning in the TV

On the second TV set, tune in a blank channel to the channel number that’s set on the modulator. Again, this will be a channel between 21 and 68.

Note that the modulator transmits an analogue TV signal. Make sure the TV is set to Analogue not Digital (a.k.a Feeview). Refer to your TV’s manual if you’re not sure how to tune in an analogue TV channel.


Having problems with the RF Modulator?

Double check that you have connected everything correctly, turned on the power to the box, set a free channel and are tuned in on the TV. If you think you’ve done everything correctly, try the following:

  • Try connecting something other than the BT Vision box into the SCART on the modulator. Maybe a DVD player. If a different box doesn’t work either, that proves it’s not a problem with the BT Vision box
  • Try connecting the modulator output aerial connector into the main TV, not the one in the other room. Then tune in to the modulator channel. This will help to check it’s not a problem with the cabling to the second room
  • Try setting a different RF channel number (from 21 to 68)
  • Try with a different SCART lead, in case there’s a problem with the SCART lead

If you do these things, you should now have confirmed that it’s not a problem with the BT Vision box, SCART lead or aerial lead. If it’s still not working it’s likely to be an issue with:

  • You’re on the wrong channel, or not tuning in on analogue
  • There’s a problem with the aerial lead
  • There’s a problem with the modulator box itself


Still having problems, please add a comment below, and we’ll try to help.


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This entry was posted in BT Vision, Digital TV.

3 Responses to Using an RF Modulator box

  1. Richard says:

    I have just purchased a second ( smart TV ) for the kitchen, I have BT vision ( grey box ) in the lounge and co-ax connection between, The smart TV is picking up the channels but all are scrambled with broken sound do I need to fit a modulator or could this be a co-ax issue ?

    • TV Answers says:

      If the channels are appearing, you don;t need a modulator box. It’s either a cabling issue, or the RF output from the Vision box is clashing with another channel. Try setting a different RF channel on the Vision box, and check your cabling is ok

  2. JW says:

    Have just bought one of the Maplins modulators as they are currently on offer and I have an old tv without a scart connection.

    I have been able to set up the tv to receive freeview through a digi box via trial and error.

    My only problem is, is that there is a high pitched whine.

    Could this be that I haven’t set the switches correctly?

    I left them in the default mode as I have no idea which channel I should set them to.

    From returning the digi box on 4th I could see that different tv channels seem to use slightly different broadcast (?) channels, ie some are on 22, some are on higher numbers.

    Can you advise me on this.

    I would prefer to keep the old telly because in fact its sound is so much better than small digital TVs were the speakers are so puny the sound is always muffled.


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