As your oscilloscope has a high impedance its obvious it may see something, but if your receiver looks dead, maybe your tandem match is the problem, bad cores, wiring shortage, wrong connected/wired, as even with 10W RF no voltage at the TP.
Good luck?
73¡¯s, Nanko, PA0NVY
Ps: I¡¯ve assembled a few ATU-100 without problems, currently working on two 1kW from EU2AV