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Dan,
I added the GA-35 antenna for my GPS-175 just aft of the Dynon GPS and ELT antenna on the aft top fuselage skin. It is probably the best location for following Garmin's mounting instructions. In IFR, you really want to have a reliable view to the GPS constellation. I did have to fabricate a doubler, but that was fairly easy to make and install.
Rough position on the upper aft fuselage behind the ELT an
I have installed the GA35 on four aircraft on their glareshields and they have performed well; two were RV's with aluminum glareshields, and the other two had fiberglass. The fiberglass has to have a ground plane under it with a radius of 7.5 inches. The manual says it can be heavy duty foil tape, but I used some thin aluminum sheet, and had the screws from the GA35 bonded to it. One was a VFR install and I could not get the full 7.5 radius for the ground plane, so I made it a bit narrower and wider to fit, and it worked well. I painted them all with flat black non-metallic spray paint; Just make sure you have the correct length of coax going to them and you should be good.
Off topic, but that paint looks amazing!I added the GA-35 antenna for my GPS-175 just aft of the Dynon GPS and ELT antenna on the aft top fuselage skin. It is probably the best location for following Garmin's mounting instructions. In IFR, you really want to have a reliable view to the GPS constellation. I did have to fabricate a doubler, but that was fairly easy to make and install.
Rough position on the upper aft fuselage behind the ELT antenna.
mine is also about 6 inches back from the dynon gps . possibly not the ideal location after reading some reports about oscillation in GA35 taking out all nearby GPS receivers. If I lose the gps signal abruptly powering off the garmin gps/antenna would be on top of the list.
Following the imanual is a good place to start:
You would think a $12K GTN-650 would incorporate this solution to their known problem…...just buy one of these in any case...
Ted 4-70 GPS Notch Filter | Aircraft Spruce ®
Ted 4-70 GPS Notch Filter 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.www.aircraftspruce.com
If you mount the antenna where it belongs and use good coax/connectors you wouldn't have that problem
I have mine under cowl also right next to the Dynon gps antenna
Thanks for the comment. I gave this some thought, but not something I really want to do. I would have to relocate existing stuff and it blocks access.
I like this idea and will see if it works.The following 1.) Can't possibly work, 2.) Will not work when you need it the most, 3.) Will cause death & destruction, and 4.) Is specifically banned in Canada...
View attachment 74769
Note that the 3 inches from the windscreen applies to roof mounting where you would be mounting the antenna just aft of the windscreen. They want a ground plane to extend at least 3”.
Well - they do document it in the docs...but, yeah....
why would an overhauled navcom be affect the gps signal different than a non overhauled? Is it the location of the actual antenna or the coax line also that must not be near the navcom antenna or coax line?
Harmonics, sometimes a result of output circuit tuning in those old radios.
The following 1.) Can't possibly work, 2.) Will not work when you need it the most, 3.) Will cause death & destruction, and 4.) Is specifically banned in Canada...
View attachment 74769
Carl beat me to the answer yet again.
Thanks will have to see, there will be some shadowing from the engine exhaust nacelle, should have a clear view of front and back and right side, but that left side will have shadowing, the exhaust nacelle is about 4 inches high there and about 8 inches from the antenna. The antenna will be where the red dot is inside the blue circle.
To me, the bigger problem here is the mask that's being created *on all sides* by submerging the antenna into a pocket. Granted, a FF installation will have some masking to the rear, by the firewall, but if mounted as close as possible to the cowling and at least a few inches forward, that's minimized. This installation creates a solid mask for the entire 360 degrees of azimuth.
I wouldn't recommend this.
[sigh] I see a lack of understanding of the basic math geometry here. At the circled-in-blue location, the airframe blocks nearly half of the close to the horizon solid angle. This is exactly where gps satellites are more likely to be. Furthermore, it is these satellites that have the best geometry for determining your position. Satellites that are straight overhead are great for figuring out your altitude, but useless for finding your position over the earth. The ‘red’ location is much better than the ‘blue’. Yes, the ‘red’ would be even better, by a bit, if you moved it forward to over the pilot’s head, and moved the huge antenna that’s there now somewhere else. You’d probably gain 2 knots as well!Does the antenna work under fiberglass, might mount the antenna under the fiberglass cone that screws onto the back of my wingtip if that will work, that way no drilling, thats just a fiberglass cone that screws onto the back of the wingtip tank and should hardly be anymore shadowing than when mounted on top of the fuselage, some forward satellites may not be seen. This is not my 310 but one I found like mine on the internet showing the cone
