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Copyright: Sindre TORP

The above picture is of the prototype of the 1-A PBT, which is in the Drake Company Museum , in Franklin Ohio.

 The unusual part of this assembly is the way it tunes the four coils.  If you look under the black and white decal you will see the bottom of a large nut.  There is a washer soldered to the shaft that fits the threads of the nut.  The washer was fitted to the shaft to be in the center of the nut.  The back of the shaft is attached to a vertical square plate, which holds the four slugs protruding from each of the four coils.  As you rotate the shaft to the right, the washer inside the nut moves the shaft inward and rotating the shaft to the left causes the shaft to move outward, which in turn forced the square plate to move in and out, thus tuning all four coils at once.

Although no one has ever told me differently, this piece of engineering has all of signs of being a product of Milt Sullivan.  Milt was one of the first Mr. Drake hired to help him start the company.  He was the Chief Engineer for many years and knew how to make things work.

The production model used a cam to move the slug rack in and out.  This design followed through in the 2-A, the 2-B, and also in the R-4 series receiver PBT assembly.

Bill Frost

08/31/05

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Last updated on: 24 Dec 2011