Service manual

Model 2A Operation And Service Manual
2A Manual A5 21 January 2005 Page 10
2. The Loop Aerial
The loop aerial supplied with all units has been found to be the best type available
for this application, achieving excellent temperature performances with no
significant phase effects. (In comparison, ferrite rod aerials are very temperature
sensitive and will contribute significantly to the phase noise in the system).
The loop aerial and its associated active components are powered with
DC via the
BNC aerial connector, eliminating the need for a separate power supply. In the
event of an accidental short circuit occurring at the
BNC socket, protection is
afforded by an internal, 20mm fuse, which may readily be replaced.
When setting up the aerial, open the loop out to achieve the maximum area
possible (a circle is obviously the optimum but, providing it is reasonably open, the
actual shape is not critical). The plane of the loop should be oriented until the
transmitter also lies in that plane. Under this condition, the enclosed magnetic field
strength of the received signal (and hence the indicated, received signal strength)
will be a maximum.