17 Apr
2004
17 Apr
'04
5:35 a.m.
> A porcelain knife switch, used for disconnecting
an aerial from a
> radio receiver. The two centre terminals of the switch are
> connected to the radio and the two left-hand terminals go to the
> antenna. Finally, the two terminals on the right are earthed. The
> switch incorporates two spark-gaps which are intended to prevent
> lightning from damaging the radio. But the real protective measure
> is to switch the handle over to the earthed position whenever the
> radio is not in use. This connects the aerial directly to earth,
> and disconnects it from the radio.
That is a darn good idea.
Often used in reverse for bringing 'Monsters' to life. :)