Please tell me my findings are completely misleading and
any concerns are unfounded.

We are in the throes of considering fitting a Navtex
receiver but having been warned the air generator we have
fitted could cause havoc with Navtex reception. I held a
portable radio in the vicinity of the generator tuned as
close as it would allow to the Navtex frequency (540 kHz).
Whilst there was no interference from the generator there
was considerable pick up from the Simrad IS15 instruments,
which appears to be emitting from the instruments
networking (Roblink) cabling. Disconnecting the NMEA made
no appreciable difference to the interference being
detected by the radio. The interference is being received
if within 6 foot of anything metal on the boat.
Mast, rigging, guard rails, keel and any wiring. As far as
could be determined with a simple radio the interference
extended up to about 3 MHz.

Questions

Could this interfere with satellite reception of Navtex
signals 200-300 miles from base transmitter.

Is this normal for Simrad IS15 instruments or is this
something relative to our installation.

Could fitting screened twisted pair help to eliminate
interference or could that in turn create secondary problems.

Request

Would anyone with Simrad IS15 instruments please carry out
the same test as myself and advise if you get the same
results and do you have Navtex and receive satisfactory
reception some distance for the transmitters.

I apologize for my first posting rambling so much but
I can't get my mind around this and feel I must be
misinterpreting, or missing something.


kind regards Tony.