Your global positioning system receives its positional information at 1575.42 megahertz. The communications radios on-board your aircraft typically broadcast in the 121.5 megahertz range. That is a wide separation in frequency bandwidth but it's not the complete picture. Your comm's are also producing harmonics which can produce significant noise at the GPS frequency. Now you can filter that signal and avoid potentially hazardous situations.
Installed GDL-82 in aircraft with existing 430 (non waas) and MK12D. Install was uneventful until the diagnostics test. 430 passed test, MK12D when transmitting would cause interference and 3D Fix would drop out on all 12 frequencies tested. Installed Garmin Notch Filter and 3D Fix continued to drop out on all 12 frequencies. Replaced Garmin Notch Filter with same part number just in case first filter was inoperative and of the 12 frequencies tested 4 of the 12 failed. Ordered, installed, and tested using TED 4-70 Notch Filter and all frequencies passed. In my install the TED filter was well worth the investment.
Failed the EMI test with my Michel radio and Garmin GPS 175 install. Installed the Notch filter and no drop out across the frequencies specified in the Garmin ground EMI test.
I purchased this filter along with the Garmin specified filter, which is manufactured for Garmin by a German company called Telegartner. The TED is more expensive, but in my installation outperformed the Garmin filter. I needed notch filters on my two Narco MK12E Nav/Comm radios after installing the Garmin GDL-82 ADS-B out solution. The Garmin notch filter worked on Comm1, but not Comm2, even though its antenna was farther away from the GPS antenna. The TED unit worked perfectly. My interference turned out to not be caused by my 121.5 mhz ELT radio, just the Narco radios.
Works perfect once all bases covered. Needed filter not only on comm but also on ELT.
Works well. On 430W satellites page, all sats go to zero when pressing PTT on 121.xx and 131.xx frequencies. GPS reverts to dead reckoning, AP shuts off. My avionics shop suggested installing up to four filters on the ELT and COM lines. I only needed two one on my Narco MK12D and one on my old Ameriking ELT. Now, satellites barely degradate at all (ever so slightly shorter height on the little icons on the sat page). No loss of signal, no problems. Turns out, this is pretty common. If youre having this issue, Google around, there are a lot of forum posts of folks with similar problems.