430W Interference

[jtrusso]

I'm having a 430W installed in a Cessna (sorry for the non-RV post) and the avionics tech is having trouble getting it done. The GPS is interfering with the #2 radio and the DME. I'm having a hard time believing what this guy is telling me so I thought I'd run it past the VAF brain trust.

He claims that Garmin states that there is a known interference "on certain frequencies" (what they are he doesn't know or won't say) when a 430 is installed in a stack with older King radios. He's telling me I have two choices:

1) buy a new Garmin SL radio or
2) he'll sign off the plane works "today", but he'll give no warranty that it's good any other day

This all sounds like shady BS to me, and he's been working this install for about 4 months now trying to track these problems down.

Has anyone ever heard of anything like this before? Should I be taking my plane to another avionics shop?

Thanks for the help, you have got to love VAF!

[jwriteclub]

For what it's worth I've flown hundreds of hours in two 172s with 430s, one above kings and one above the really old nixie tube cessna radios. Never had a problem.

~ Christopher

[AlexPeterson]

There is a length recommendation for the coax going from the 430 to the new waas antenna. I can't recall exactly, but it is in the teens of feet IIRC. Too short and there will be problems. There is another thread in this forum - probably search for waas and 430 - that discusses some of this.

The test they are referring to is simple. You turn the 430 to the satellite page, and watch the various signal levels while transmitting on each com radio. There is a series of frequencies that are each tested. I'm not sure exactly what the satellite signal strength criteria is, but that is the test. We transmitted also on the 430's com during this test. I never saw any movement on the satellite page signal levels during this test on my plane, which I helped do.