Thanks Duncan J and Alf...
Yes Carfax, not to be confused with Trevor Brook's https://radiofax.org/work_in_progress.html
Strange Carfax used 4.5kc below 531kc, why did they not use 522Khz? must have been some reason
526.5khz would have made a whistle with any night time 530kc.. We never do UK things Logically
Was the idea, for people to listen on normal Car MW sets? or were special receivers planned?
that they could charge you for?

Another weird system, tested in London around 2010 from Crystal Palace mast, was using dipole
for DRM tests on 25.7 MHz. by VT Merlin. What became of that tests?
https://tx.mb21.co.uk/gallery/gallerypage.php?txid=1&pageid=721
Scroll about half way down, to see pic of it

To get back to the thread... Re DAB sets, Not having an Aerial Socket, If you want to use a
Communal aerial Wall socket, say in a flat etc, one idea that I feel should work is...

Make up a length of Coax, with Plug one end for Wall Plate (Belling Lee or Screw on "F" type)
Other end, Split the Inner and Outer, and Spiral Wrap the Inner, round the Telescopic aerial
Outer Braid, put near rear of set, (poss. with piece of Cooking foil, to Capacitively couple it)

Rescan... to see what Extra multiplexes you can get ...Idea might work on FM band as well
What shall we call it ?...A Caroline Coupler?

Rod Watts