tests=QUOTED_EMAIL_TEXT,REFERENCES,SPAM_PHRASE_05_08,
USER_AGENT_OE
version=2.42
Chaps
A couple of people say:
> I have a Navaid Devices wing leveller fitted. When the PTT switch is
pressed
> to send on the radio, if the wing leveller is functioning, the aeroplane
> does a violent turn to the left!
This sounds like an electrical nightmare to me. In my professional
life, my company manufactures navigation and radio equipment for fitting
into road vehicles, and we have to do extensive testing to avoid this sort
of thing (you need to prove that you won't set off the air-bags when
you turn it on etc etc.)
Alex is correct to check your radio is working properly, but I assume
that it is (or you would probably know about it), and the whole idea
of a radio is to emit pretty energetic waves anyway..... Check the
antenna cable anyway - it should be easy enough I presume.
It seems to me that the Navaid unit is susceptible to radio interference
which is causing the problem. I would have thought that Navaid should
have designed their unit to withstand this (as they can expect you to have
a radio nearby), so they should be able to help you.
If not, and this was one of our boxes, then I would suggest a couple of
things, in the following order of effectiveness and convenience:
- Put the Navaid box in a metal outer box, if it is not already. Ground the
metal box (connect it to 0 Volts). This will screen the unit from
penetrating radio waves. If it is already in a metal box, inspect the
cable and connector back to 0 volts. Make sure the conductor itself is
well made, is as short as possible, and is at least as highly current
rated as the power cable.
- The cables in to and out of the box will work like fairly efficient
antennas,
and will conduct the interference inside despite there being a metal box.
The
way to fix this is to clip on a ferrite core as close as you can to the
box entry point. You can buy clip-on cores from most electronics stores.
Clip
cores onto the longest cables first.
- Screening the cables. Use a screened cable, bonding the cable screen at
the
(now metal) box end. Depending on the cable routing arrangements, this
might be
too much to ask........
By-the-way, please take these as generic suggestions only, I have no
specific
knowledge of how the Navaid system actually works!
Simon
~~~~~
|