In the case of radiated interference, all the shielding on the world -
aluminium, copper, foil, wire wool etc - is of no use unless it is correctly
earthed (grounded) by a low-impedance at a single point.

Filtering is the correct approach for conducted interference. In most case,
a device that puts HF noise into the power feed (e.g. a swiching power
supply) is radiating as well, so correct screening is also required.


"Eric Greenwell" wrote in message
.. .
In article ,
says...
All the cables in a glider I was having RFI problems with were shielded
with aluminum foil. The RFI continued, as evidenced by squelch on the
Becker Radio 123.3, 123.5 & 123.0. Added more foil around the power
converters, radio, GPS cables, radio antenna cables, power supply cables
etc. the RFI continued. So oviously the foil is not the answer. Unplug
any
of the following instruments and the RFI stopped, Ipaq, L-NAV, either
CAI
GPS Nav (there were 2). Finally traced the problem to a power
converter,
replace it with a PWR-5b that I sell on my website and the problem was
solved, with no aluminum.

It's always best to eliminate the source! And, of course, if the noise
is being transmitted through the cables instead of radiated into them,
shielding won't help. Filtering usually will, such as the ferrite
cores seen on many cables.
--
!Replace DECIMAL.POINT in my e-mail address with just a . to reply
directly

Eric Greenwell
Richland, WA (USA)