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.

I tuned the rig up on 1610, a clear spot just above the broadcast band. Then I put a broadcast receiver on the frequency at home so my mother could monitor and know where I was.  I was probably a little ahead of my time in the use of that frequency, which is now used for highway information and weather conditions, along with 530 kHz. 

 

Bill Caldwell, W9ALM