On Wednesday, September 17, 2014 12:57:59 AM UTC-7, Steve Parker wrote:
Hi,

I really like the look of the Butterfly vario, it ticks most of my

requirement boxes.

Where do most people fit their sensor box given the requirement to be 100mm

from data wires and metal, 150mm away from avionics, 300mm away from 2 amp

cables and 500mm from a speaker?

I realise gliders have different positions for wires and speakers but I

would like to know how others have positioned their box.

Regards,

Steve.

I mounted mine under the glare shield in the panel, as far from the other instruments as possible. I also redid the power/grounds to the other instruments, twisting the current carrying pairs and routing away from the ISU as much as possible. My large speakers are behind my head, but I left the small one in the spare Illec vario about 8" away from the ISU. I did not achieve all of the installation requirements to the letter, but after the install I tried moving power lines, metal bits, and magnets closer and further from the ISU in different directions while observing the heading (magnetically derived). From that experiment I surmise that the installation instructions are conservative. In theory you can compensate out static interference sources (like metal, constant DC currents, etc) but cannot comp changing sources (varying DC currents, rotating magnetic compass cards, etc.).

My installation has worked very well, with no problems due to location or interference.