From a previous posting on the LML about solving RFI problems:

More Black Art!!!!

Any technology, sufficiently advanced, is indistinguishable from magic.

If only we could see RFI.

While we can not see it, we can definitely understand it.  Let me indulge you with an excerpt from an essay on Taoism by Thomas Cleary:

According to an old story, a lord of ancient China once asked his physician, a member of a family of healers, which of them was the most skilled in the art.

The physician, whose reputation was such that his name became synonymous with medical science in China, replied, "My eldest brother sees the spirit of sickness and removes it before it takes shape, so his name does not get out of the house.

"My elder brother cures sickness when it is still extremely minute, so his name does not get out of the neighborhood.

"As for me, I puncture veins, prescribe portions and massage skin, so from time to time my name gets out and is heard among the lords."

Lets apply that principle of Taoism to RFI.  The most skilled person sees the spirit of RFI and removes it before it gets to manifests itself.  By the time things get to the point where someone has to fabricate shields, prescribe ferrite beads, and massage wires, something has already drastically gone wrong.  Yet it is such actions that make headlines and the practitioner's name is heard among the lords that own Lancairs.  Those that squash out the spirit of RFI before it gets to manifest itself are rarely heard from or talked about.

There are plenty of aircrafts flying with exactly the same combination of  equipment, yet some have problems and some don't.  What is different?  In most cases it comes down to wiring and installation issues.  Are things properly grounded?  Are there ground loops?  What is the power distribution grid like?  What is the quality of workmanship? Are cables/connectors properly terminated?  Hint: The difference between the $500 specialized crimping tool and the generic $20 one that you buy from Radio Shack is not limited to their price.   This is a case of you get what you pay for.

When designers design kit aircrafts, they design in a huge safety factor for the builder's quality of work.  However, avionics manufacturers do not leave much margin -- they (we) can not.  When you are measuring voltages in the vicinity of 1 milliVolt and resolving them to the accuracy of 22 microVolts to get 1C resolution out of a thermocouple, it does not take a lot of leakage out of a comm antenna to see temperatures that are out of this world (temperature from the next world, specifically from the section reserved for terrorists and the like).  The leakage from the radio does not have to come on the antenna line only.  It could come out of the power line or the ground line if they are not set up properly.  The noise could be ground noise from the additional current consumption of the radio as it draws more power during transmission.

The key to avoiding these problems is to the design the installation properly and maintain high quality workmanship.  There are plenty of  good books on the subject that can educate you if you chose to do the installation yourself.  Alternately, there are plenty of reputable shops with a proven track record, that can design and build the panel for you and assist you in the overall electrical design.  Cutting corners with using cheaper connectors, lower grade wires and improper crimping tools is only going to come back to bite you.

This posting is not intended as a slam against anyone who is having problems with RFI in their airplane.  It is just a reminder to not dismiss the electrical issues as trivial.

As I review this posting, it sounds like it is coming from a politician whose political party is out of power; full of criticisms and completely void of specific suggestions.  If I can make only one suggestion, it would be to take the problem seriously and to seek competent professional help.  This help can be in the form of training (hands on or reading books), assistance/supervision/mentoring or hiring out all or most of the electrical design and assembly.  The second suggestion would be to not skimp on tools, cables and connectors.  Make sure you get high quality connectors and appropriate crimping tools when crimping tools are required.

Regards,

Hamid
Standard disclaimer about affiliation with Chelton Flight Systems.