The PTR1751 controller looked a bit like this, but the one in the Swinderby Chippies had the anti jam switchery. It says V/UHF on the box as did the one in the Chippy, but it just controlled the UHF. There aren't any pics on-line of the actual box that I have found, probably as the box and it's functions are classified!
Edited to say that someone has put details of the PTR1751 controller as fitted to the Chippy on-line. From a JP3 manual by the looks of it.
http://www.clayworthroad.co.uk/page1...0Equipment.pdf