The Broadcaster® was the original Telecaster® model in the early 50s before evolving into the more classic Telecaster® we know today. The only electronic difference between these two models is the way in which they are wired.
Rather than conventional 3 way switching on a regular Telecaster®, the early 50s Broadcaster® uses a blend control instead of a tone control.
The blend control opens the door to being able to blend the neck pickup in with the bridge pickup. The circuit also makes use of a fixed value 0.047uF capacitor for the neck pickup in the third position.