Dodd Station


Posted on Feb 4, 2014

Fortunately, Dodd`s 1909 receiver has survived. It was found among the many parts that were in various boxes that I had purchased at the yard sale. The pieces were identified from the 1909 Station photo. Many of the 1909 Station parts were used in the construction of Dodd`s 1912 station. The most obvious component is the helix that changed very little in its incorporation in the 1912 station. I restored the 1909


Dodd Station
Click here to download the full size of the above Circuit.

Tuning Inductance in 2009 and it, along one of the home made detector stands and the single Kellogg earphone that Dodd is using in the photo, is now on display in the Museum. Since the inductance (and receiver) is so primitive, I have also included a copy of this photograph in the display so viewers can recognize that the components they are looking at is actually a 1909 receiver. The Transmitter Basics - Dodd`s 1912 station uses what was called a Damped Wave Spark Transmitter. The actual radiated signal is in the form of a pulsating wave train made up successive damped wave oscillations at a radio frequency determined by the LC of the Sending Condenser and the Helix. Damped wave means that each successive wave peak in each damped wave oscillation pulse is of reduced amplitude compared to the proceeding wave peak. An ideal decay or decrement of the damped waves would produce strong RF signals that could be copied at a great distance. The damped waves were created in the following manner. The Spark Transformer provides a high potential AC that is allowed to charge a Sending Condenser on the increasing positive voltage of the AC. When the charge voltage reaches a high enough potential, the insulating properties of the Spark Gap break down and the gap arcs over which effectively removes the transformer secondary from the circuit by a temporary short. However, the Sending Condenser then is discharged into the Helix. At this...




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