[Radioroslyn]

I'm not quite sure that I know what you mean when you say nothing comes out?? If you put a 100mc signal into the ant connect can hear it at pin 5 of the 12BA6?? Now you realize if you are using an AM generator set for 100mc your FM detector won't detect an AM signal. It's designed to detect a change in frequency not amplitude. That's why I said to use a signal tracer which will detect an AM signal.
Can you hear the signal from the generator at pin 5 of the 12BA6? In lieu of using a tracer you can use a scope but must have 100mc response or better. If you do then have a look at pin7 of the 12AT7. If not check voltages at 12BA6.
Terry