Here is what might have been the first bicycle transmitter
From the site:
Here is what might have been the first bicycle transmitter, a “breadboard” model I built in 1938.† I am shown “tuning up”†the rig, with two†grade school friends looking on.¬† I used a type 30 oscillator, another 30 for the modulator, and two 45 volt “B” batteries in series. The antenna was my fishing rod.