Note
CQ, May 1955, page 68.
The difference between the "A" and "C" versions appears to be the type of microphone connector used, as both early and later versions have been found with three different styles of connectors.
As the manual does not show or describe the connector in detail, and since users could easily modify the patch with any type of connector they found most useful, it is hard to know exactly which connector goes with which type.
Matches the 583 Q multiplier.
