[GadgetM]

Thanks cheerfulcharlie, but I already have an rf modulated freeview box, my reason for wanting to insert composite video was to bypass the 'out-of-alignment'- tuner/IF section.
The picture has a lot of colour subcarrier noise and I just can't seem to dial it out with the appropriate filter coil so I thought "sod it... I'll see if I can bypass it altogether and inject composite video instead"