You could certainly be right, as there is no guarantee the measurement was made in a sane way. The reason I concluded he was talking about the diaphragm coil w

You could certainly be right, as there is no guarantee the measurement was made in a sane way. The reason I concluded he was talking about the diaphragm coil wire is as follows: it would seem a lot simpler to measure the cord length by a simple ruler, whereas precisely as not to destroy the diaphragm coil one may be tempted to estimate that length by counting the number of loops and measuring the diameter... Anyway, the story reads very apocryphal because there are no pictures, its unclear language, and the implication of unintentional FM reception is rather ... hard to fathom.