Hello John,
I have one of those too! Identified some years ago in this thread with some information:
https://www.vintage-radio.net/forum/...d.php?t=105868
Since then, the schematic has turned up too, but I'm not sure where it will be amongst the museum side of things collection (need to be more organised for 2019 . . . !)
It's on our GATV website now here:
http://www.golden-agetv.co.uk/equipm...ProducerID=137
Best regards,
Paul M
www.becg.org.uk
www.golden-agetv.co.uk
www.projectvivat.co.uk