V

vonjet

Well Known Member
Hi everyone,
First off, I have a Lancair and I installed the GRT sport EFIS. My problem is my magnetometer is showing magnetic heading swings fairly large when I key the mic.
The wires to the mag are bundled with the comm coax for about 4 feet then they separate.
I cant get the problem to go away no matter where I place the Magnetometer. GRT says the coax cable itself should not affect it but its proximity to the antenna itself will. My antennas are at least 5 feet away and it still does it.
If it makes any difference I am transmitting inside the hangar.
Any suggestions to a fix?
Thanks
 
I would not be too concerned about it till you move the plane outside. The RF can be bouncing of any of the walls the VSWR may be high inside the hanger. Check it outside first. Make sure you have installed the antenna with the proper ground as per the manufactures installation instructions.
 
Mag & RF

I had a similar problem in our Europa.

First, try it outside to make sure its not a problem of RF bouncing around the hangar.

I checked out my comm antenna. Be sure the standing wave ratio SWR is low, say less than 1.5:1. I contacted the local ham radio club and found a guy with an antenna analyzer. We checked my antenna and ended up making a balun for it. Similar in design to the one shown on Aeroelectric. I can give more detail if you need them.

I ran shielded cable to the magnetometer. Grounded the shield at the DU only. I wrapped the magnetometer in aluminum foil and connected the shield wire to the aluminum foil. I also found a DB9 filter helped.

If you need more info contact me off list, or contact Carlos at GRT - he's very familar with what I did.

Jim Butcher
Europa N241BW
 
Hmmmm.

I haven't had it outside yet. I will try that. I found out that the wire to my magnetometer is shielded, but my avionics guy cut added an extension to the unit and cut the shields so there was a section that not. I am going to fix that and then look for a new spot for it to test as the original spot was too close to my comm 2 antenna.
 
You must log in or register to reply here.