A few weeks ago, while passing through KC center, I was on 132.7. On both Garmins, this distinctive rythmic sound was in the background. It wasn’t center’s problem, but mine.
Went to Business Aviation in FSD (a SC) and our trouble shooting ruled out the Garmins. Ended up being the EMAX module. Am waiting for a replacement now. What was strange was that it wasn’t on any other freqency that I could tell. It also initially sounded like it might have been bleed over from a mag or alternator.
Just thought I would pass this info along.
David Schwietert 203 RF PFD/TKS/Emax/Skywatch/Stormscope
I wrote “had” because when I changed frequencies, it went away
I believed it to be an aircraft noise problem, rather than noise being received
by my radios, because I found if I turned off Garmin #2, the noise went away
on Garmin #1, yet the noise always showed up on Garmin #2, whether
Garmin #1 was on or not.
I don’t use that frequency much, and I have’nt noted this issue on any other
frequency, although I’ll try the 132.7 where you’ve noted a cyclical noise pattern.
Now you got me thinking and I think you may be right. Switched from Denver Center 127.95 to 132.7. The next hand off was KC Center. Good Catch.
Our first inclination was something related to the alternator or Mag. I first only noticed it with engine power (flying). Just before visiting my SC, I turned on the battery switch and then avionics. Turned to 132.7 on both radios and there it was. So, it was not connected to any electrical interference caused by the running engine. An astute mechanic and avionics tech. next had the idea that it might be related to the emax, since nothing else was on. All other possible related CB’s were also pulled with no affect.
Once we removed the plastic knee shield, we then pulled (one at a time) the plug-in bundles (there are 2) and one of them cancelled the cyclic sound.
Hope that answers your question. Waiting now for the new SIU. Will keep you posted.
Tried 132.7 again on the ground, and experienced the same rhythmic sound. Pulled the EMAX breaker- no sound. After calls to Cirrus and Avidyne they say that this is a known issue and to expect an SB within weeks. This will involve adding some type of filter to the SIU.