SAT magnetic pick up

[Michel Lachance]

I had a strange experience once when I was tuning a piano in a recording
studio.  During the FAC measurement, I was getting a negative stretch for the
first note (which is quite unusual for 7 foot grand Yamaha...!)  As I heard a
kind of low rumbling noise caused by the air vent, I tried to used the
magnetic pick up to see if it was not the cause of some interference - even
though my SAT did not show anything unusual.  However, with the pick up on
and the SAT set on F5 for the first reading, the lights started to slowly
turn counterclockwise WITHOUT PLAYING ANY NOTE ON THE PIANO.  The only
explanation I have, so far, is that an electromagnetic interference of a
definite frequency equivalent to a slightly underpitched F was omnipresent in
the room.  I know it was not caused by martians because I did not see any
alien spacecraft flying over the building :-)

Seriously, it was the only time a magnetic pick up was of no use in the FAC
measurement.  Has anyone experienced something like that?

Michel Lachance, RPT