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| Type 31 receiver schematic. The aerial tuning
inductance is at the right side. The primary and secondary coils are at
the top left of the schematic but no coupling arrow is provided.(Courtesy
Handbook of Technical Instruction For Wireless Telegraphists). |
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| Type 31C receiver with aerial tuning inductance
on the left. The degree of coupling between the primary and secondary windings
inside the the receiver can be varied by moving the handle on the
front along the slide . A half turn of the handle locks it in position. |
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| Type 31 receiver. In this example, it is
presumed that the primary and secondary coils were external to the set,
hence the difference in dimensions. If that is the case, that also explains
the absence of the slide control. (Photo courtesy Museum of the
History of Science, Oxford) |
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| Top view of 31 receiver. (Image courtesy
Radiomuseum.org) |