Aha,i didn't now.But what means Receiver RG ??And were has the Navy it used for.It's almost identic to Type K.There is a lot about this equipment(Tabby's) but not of this Model?That is Strange!So many models and pictures of these models and discriptions of them.What i found on the internet is (See LINK) http://www.rnmuseumradarandcommunications2006.org.uk/LIBRARY NAVY LINE 1 TO 686.htmlibrary File 19 is mentioning H/B ON THE USE OF RG APPARATUS, (INCLUDING RG RECEIVERS PATT, W6815 ANDPATT, W5766). 1943.I hope Somebody has some old military pictures for me of this Receiver.(In yuse of, or on a boat??)