Fm is line of sight right?
So 8 watts line of site here on earth will go how far?
That high of frequancy the antenna would not need very long active elements, but the number of reflectors and directors would be rather large to get it pinpointed back to earth.
I will have to google this and see what their antenna looked like.
Done right, a antenna can be very directional, the 1's I built,a slight twist either way and poof,no signal.
YOu were so lucky to be able to work with foot warmers,I mean vacuam tubes.
I came up to late to learn much about them but still I worked on that kind of stuff for years as a hobby.