Install ferrite beads close to the source of interference. It does not help much if there is two
meters of cable between source and ferrite bead. Distances as shown in the photo are
correct.
Multiple wires may share a single ferrite bead with the exception of the GPS aerial antenna
which requires a ferrite on its own.
In case of the GPS aerial, loop the cable twice through the ferrite. Notice the size of the
loops. Never loop this cable tightly, you will greatly reduce the sensitivity and performance
of the GPS system if you do. The size of the loops in the photo is correct.
Other wiring should be looped tightly as shown in the photo.
The more loops you can place around a ferrite, the better the effect.
Please note again that ALL wires leaving the instrument should have a ferrite bead if you
have problems with RF interference.
Identifying RF interference sources:
Enigma creates a signal that is highly dependent on the contents of the display and may
sound like an “angry grrrrrr”. If you have radio noise, change the screens to see if the
noise pattern changes as well. If it does, start identifying which cables are used to transmit
the noise to your radio. Enigma itself does not transmit a significant signal due to strict EMI
design techniques however, small signals may readily leak and use any attached wires as
convenient antenna for transmission. Thus, remove the wires one by one. Start with the
GPS – this is a long wire and may contribute significantly. You can remove this wire with
the instrument switched on. Then try the audio and airtalk cables which can be unplugged
easily, This way you will quickly find the source. Place ferrites as needed or reroute the
cable to improve the situation.
A good installation should not generate any noticeable RF interference on your VHF radio
with the squelch fully opened, you should hear only static noise.
Note that inside metal hangers noise interference may be considerably worse in some
cases. Always check outside a hanger and move at least 100 ft away from any hanger
structure.
