G GLENSOUND ELECTRONICS LTD
G GLENSOUND ELECTRONICS LTD. Tel: +44 (0) 1622 753020
6 BROOKS PLACE, MAIDSTONE, KENT, ME14 5HE, ENGLAND +44 (0) 1622 753662
Fax: +44 (0) 1622 762330
COMMENTATORS EQUIPMENT WARNING NOTES
DATE 29/01/98 FILE No PT14-02 ISSUE No. 1
There are two important points to be wary of in this equipment. Both are associated with
the fact that the Commentators Box is powered from the Base Station:-
1) Because current flows in the co-axial cable (aprox 300mAs) to power the
Box, it is inevitable that a potential difference will exist between the Box metalwork and
the Base Station metalwork. On a long line this can amount to several volts. If the
system is then tested with test equipment that shorts these two earths together, the system
can become severely upset and fail. It will resurrect itself when the earth loop is
removed.
2) If you test this equipment with the co-axial cable wound in a coil beware.
The coil of cable forms an inductance. This inductance has 300mAs flowing through it.
If the co-ax is then disconnected a large back EMF is produced. This is large enough to
give you an
* * * ELECTRIC SHOCK * * *
if you are holding the co-ax plug and socket.
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