Radio Frequency Interference
Radio Frequency Interference - General Wiring Guidelines
a) Keep the antenna cable away from any other wiring and ensure that the cable is not routed close to the display.
b) Do not mount the radio close to the display - some handheld models are poorly shielded as this is not normally a requirement for a hand held unit. If you place such a radio close to the display, the unavoidable EMI in front of the display may be received by the radios front end amplifier directly.
c) Ensure you radio and intercom wiring (power supply included) are not routed near the display.
d) Do not mount the antenna close to the display unit.
e) It is often of great benefit to provide two sets of power supply systems. Power your radio and intercom separately with own power and ground wires back to the battery.
f) Be very careful with using any airframe parts as ground wiring. This is not a good idea as DC currents will cause galvanic corrosion, in addition to any and all AC components of your power supply (including RF) will now be coupled into the airframe making this a very nice antenna.
g) Keep the instrument power supply wiring (12V and ground) plus the RDAC cable away from the radio and the antenna cable, by at least a few inches. The same applies for the ambient temperature probe.
h) Bundle up any excess RDAC cable at the RDAC close to the engine, not close to the display unit.
To find out if the power supply to the instrument it part of the problem, remove the wires (both + and ground) and supply the instrument temporarily with a small 9V battery. Does this help? If yes, route a separate set of wires to the battery for the instrument.
Last update: 2006-11-14 11:03
Author: Rainier
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