VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics

  #1  
Old 04-03-2009, 07:40 PM
vonjet vonjet is offline
 
Join Date: Feb 2008
Location: Thousand Oaks, CA
Posts: 183
Default Magnetometer and RF interference

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
Reply With Quote
  #2  
Old 04-03-2009, 10:12 PM
Norman CYYJ Norman CYYJ is offline
 
Join Date: Feb 2005
Location: Victoria B.C.
Posts: 1,266
Default

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.
Reply With Quote
  #3  
Old 04-04-2009, 08:09 AM
andyrv andyrv is offline
 
Join Date: Feb 2005
Location: Leawood, KS
Posts: 275
Default RF

Is the airplane complete or are there any wires of any kind still unterminated?

Andy
Reply With Quote
  #4  
Old 04-04-2009, 09:17 AM
h&jeuropa h&jeuropa is offline
 
Join Date: Jun 2008
Location: Kalamazoo, MI
Posts: 263
Default 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
Reply With Quote
  #5  
Old 04-04-2009, 11:51 PM
vonjet vonjet is offline
 
Join Date: Feb 2008
Location: Thousand Oaks, CA
Posts: 183
Default 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.
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 06:54 AM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.