radio interference

On Apr 28, 4:02*pm, ryanglover1969 wrote:
should I shield the cables from the vario to the colibri and Ipaq???


I think I'd first verify the problem can be reproduced using a hand
held TX. Then start disconnecting leads to/from the vario. Try
disconnecting each end of each lead in turn. Try powering the vario
from a local battery rather than ships power and wiring.

When you have pinned down the route the rf is entering the vario then
you are in a better position to work out how to fix it.

Large ferrite cores as close as possible to the vario may be a good
starting point. (They work best if the wire is looped rather than just
threaded) Changing wire routing many be another (make sure no vario
wiring is close the radio coax). If the vario outputs are typical
data and ground then screened twisted pair may be the next thing to
try. It may also help to ensure all leads feeding the vario are run
together as far as is possible. Having them spread out, or even
forming a large loop will increase the risk of RFI.

Perhaps the first question should be - did it always do this? If not
what was added or changed, or has something (perhaps rf filtering
components in the vario) failed.

Andy (GY)