"In 1957, I was an instructor in the classroom and later in the Type 7 lab. We used to indulge in a mild form of amusement at the expense of the trainees. If you remember (and your memory and recall are nothing short of miraculous), Type 7 was the first equipment after basic electronics in Block 1. We would get the results of our next intake and arrange for the brightest pupils to sit in designated places. Remember the wooden high stools!!! The radar would then be run up into the dummy load.....do you remember also that the windows were covered in chicken wire? Invisible standing waves would be set up within the lab, the nodes being always in the same place. A 1.5m dipole with a neon soldered in the middle would then be moved around the lab with the neon appearing to 'strike' above the head of the top(s) in class. Much astonished hilarity. Incidentally, your piece on the run-up sequence was right on the money. Faultfinding would normally involve this relay chassis and a fair number of the class would choose this circuit drawing because it worked only one way.