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Notch Filters?
The installation manual for my GNC 300XL calls for a notch filter in the com antenna line.
Have people found this neccessary? Where could I find one? (Googling the Garmin suggested part number only hits Garmin GPS installation manuals) Pat |
I added one...
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In my case, I upgraded an Apollo Loran to a slide-in replacement GX-55. The installation instruction gave a set of Comm frequencies to transmit on... if any of these frequencies caused a loss of GPS signal, the installation needed to be tweaked. I had a comm. antenna too close (since moved) and a notch filter in that co-ax solved the problem. Since it's a "plug-in" device, it's somewhat easy to add later as long as you can get to the coax. behind the panel. In my case I had a straight coupler in line, so I just replaced it with the notch filter. Do your installation instructions give you the specific comm. frequencies to test? gil in Tucson |
It's been a while ago and I may be mistaken, but I'm pretty sure that one was included with my GNC-250XL.
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When I ordered my GNC300XL from Stark, I asked about the notch filter. He said he didn't think it was really necessary. He said he would throw one in with it, but I think it came with the unit anyway.
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Mel,
You were right again. There is a gizmo in the GNC 300XL materials which must be a notch filter. I didn't recognize it as such because it was labled something else in German. Thanks all, Pat |
Looks like a "T"
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gil in Tucson |
Gil,
That describes it exactly. Thanks again, Pat |
In the Comm coax...
Pat... glad you found it...
Just to be clear, the notch filter goes in line with the Comm. antenna cable. You might need 2 filters if you have 2 comms. Put in in line first with the comm. that has it's antenna closest to the GPS antenna. Some details here... http://www.avionics.com/Avionics%20O...20Interference It's usually not needed in you label your GPS "VFR USE ONLY".... :) gil in Tucson |
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