Robotron Pty Ltd G5E Manuel D’Utilisation
WiNRADiO G3XX VHF/UHF Receiver
74
To check this, tune to one of the interfering signals, then switch off the monitor
and see if the signal disappears. If the interference still exists you could
continue using the WiNRADiO receiver, and live with the fact that some useful
frequencies will be obscured by your monitor’s interference, or you can replace
your monitor with a ‘quieter’ one (modern LCD displays are far quieter than old
CRT monitors), or you can try to relocate your antenna further away from your
computer.
and see if the signal disappears. If the interference still exists you could
continue using the WiNRADiO receiver, and live with the fact that some useful
frequencies will be obscured by your monitor’s interference, or you can replace
your monitor with a ‘quieter’ one (modern LCD displays are far quieter than old
CRT monitors), or you can try to relocate your antenna further away from your
computer.
A good remedy to try is to wind five to ten turns of the antenna lead-in cable
through a large ferrite core (the doughnut shaped toroid type), near the PC
end of the cable. This suppresses common-mode interference, which is a
typical but curable problem with PC-controlled receivers.
through a large ferrite core (the doughnut shaped toroid type), near the PC
end of the cable. This suppresses common-mode interference, which is a
typical but curable problem with PC-controlled receivers.
Another type of interference which you may encounter is intermodulation
interference. This is usually caused by strong local stations, whose
frequencies combine to create ‘ghost’ signals on frequencies which are
arithmetic combinations of the stations’ frequencies. These ‘ghost’ signals can
sometimes coincide with useful frequencies, rendering them partially or
completely unusable. They will usually disappear when you switch on the
Attenuator in the receiver control panel. You may also try shortening the
antenna.
interference. This is usually caused by strong local stations, whose
frequencies combine to create ‘ghost’ signals on frequencies which are
arithmetic combinations of the stations’ frequencies. These ‘ghost’ signals can
sometimes coincide with useful frequencies, rendering them partially or
completely unusable. They will usually disappear when you switch on the
Attenuator in the receiver control panel. You may also try shortening the
antenna.
If you live very close to a strong local transmitter, these measures may be
insufficient. In such case, you should be able to eliminate intermodulation by
fitting a special filter to your antenna, to reduce the level of the signals causing
the interference. The design and application of such filters falls beyond the
scope of this user’s guide. However, broadcast frequency filters and tunable
preselectors are standard items and can be obtained from good radio
equipment suppliers.
insufficient. In such case, you should be able to eliminate intermodulation by
fitting a special filter to your antenna, to reduce the level of the signals causing
the interference. The design and application of such filters falls beyond the
scope of this user’s guide. However, broadcast frequency filters and tunable
preselectors are standard items and can be obtained from good radio
equipment suppliers.