3 Feet of Superhet

A new addition to the museum graciously donated unrestored from the estate of Mel Sylvia K6CRW.

OAKLAND AUTOMOTIVE SPECIALTY CO.        INVINCIBLE

Research on this 10 tube superheterodyne leads to the manyfacture of the transformers, Madison Moore, of which it has the set of 5, numbered 1 through 5. Other leads to the Oakland auto manufacture, which became a part of GM seem to be a dead end. It is almost certain that this radio was sold around 1925 or 1926 as a kit. There are examples of an 8 tube variation for which the schematic is listed in the Riders manuals.

Underside view showing the chrome cased Madison Moore transformers.

This radio differs from the 8 tube version most significantly by the use of push-pull UX 171 output tubes which incorporate a center tapped plate choke with the center tap going to the high impedance speaker.

The first audio transformer has a secondary winding that measures 27K ohms. That must be a LOT of wire. Fortunately it is intact.

An interesting note: All of the capicitors have the values either scrapped (paper) or ground (Bakelite) off of the labels.

Video of operation. Touching controls, once tuned, is- well- it gives you something to do.

At just under 3 feet long, it take up a lot of shelf space.

The only modifications, following the original construction, seem to be the addition of a second headphone jack (interior) and combining the dial indicator lamp switch function from two switches into one. The second switch is still there but has no function.

A very nice addition to the display.