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  #1  
Old 03-03-2012, 02:25 PM
RVG8tor's Avatar
RVG8tor RVG8tor is offline
 
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Location: McKinney, TX
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Default GPS Ant under cowl?

For those that made a shelf for the GPS antenna attached to the firewall. How far below the flange of the firewall did you make your bracket and how far away from the firewall. I would like to get one made but without the cowling on and the other stuff on the engine I am not sure where to start. I don't want the antenna any lower than it has to be so as to maximize reception.

Thanks
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  #2  
Old 03-03-2012, 03:22 PM
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Default

Mike,
I've had good success recently with using 2 DG14 adel clamps on the top of the engine mount ring. They secure an .063 plate via the 2 bolts, and the antenna screws onto this plate. We have a firewall mount on my friend Greg Reese's RV8 and the XM portion of his G3X antenna is getting shadowed by the firewall. The plate on the ring will move the antenna away from the firewall and fix that issue. We had used the RV12 firewall mount bracket and thought it was positioned high enough, guess not! I have mounted my 430 antenna on the engine mount ring and it is working great.
Good luck,
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  #3  
Old 03-03-2012, 03:56 PM
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Why mount under the cowl? I mounted on the glare shield. Painted black and works great.
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  #4  
Old 03-04-2012, 04:36 AM
dav1111 dav1111 is offline
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I attached a hinge pin to the firewall 1/4 inch above the top of the motor and attached a mounting shelf to the other half of the hinge pin so that it would lay flat across the top of the motor mount extending 1 inch past. I then put a piece of foam cushion on the bottom of the mounting shelf where it lay on the motor mount so that it would not rub and after drilling two holes in the shelf zip tied it the motor mount. I then mounted the multiple GPS antennas to the top of the shelf.

I can remove the shelf by cutting the zip tip and pulling the hinge pin or just cut the zip tie and lift up the shelf out of the way if I need to do so. Never had any reception problems.

Quote:
Originally Posted by RVG8tor View Post
For those that made a shelf for the GPS antenna attached to the firewall. How far below the flange of the firewall did you make your bracket and how far away from the firewall. I would like to get one made but without the cowling on and the other stuff on the engine I am not sure where to start. I don't want the antenna any lower than it has to be so as to maximize reception.

Thanks
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  #5  
Old 03-04-2012, 07:01 AM
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I did my F1 in the same manner that Jon Thocker is suggesting. Get's your 'antenna farm' out from under the lip of the boot cowl/firewall interface and provides them with a good view of the sky. The F1 has an engine mount crossbar just aft of the baffles that works fine for this. Just mount your 'shelf' solidly and facing aft. Mine is something like 5" x 8" and holds two GPS antennas and a WxWorx antenna.

There is no particular reason to mount your antennas 'under the hood' as far as I can tell, other than cosmetic. Personally, I like the clean, uncluttered look of my 'empty' glare shield.

Regards,


Lee...

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  #6  
Old 03-04-2012, 03:19 PM
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Default Under the hood

Mike,
Mine has 2 Garmin GPS antennas and one for XW weather and raidio. 8 years and no issues at all.



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  #7  
Old 03-04-2012, 05:08 PM
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The drawback to mounting under the cowl is the basic enemy of all electronics... heat. GPS and XM antennas are active devices that have amplifiers in them, they are not passive devices like your com, xpdr or vor antennas.
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Last edited by Walt : 03-04-2012 at 05:10 PM.
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  #8  
Old 03-04-2012, 05:16 PM
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Default Great Ideas

I had been leaning towards the idea Jon had, using clamps to hold it above the engine mount.

@Walt; the problem with the -8 is there really is no good place on top of the plane to mount the GPS antenna, I have given thought to the top in front of the windscreen above the baggage compartment, but due to the door design the antenna would have to be off set from center. On the glare shield is a no go just due to room and it is kind of RFI intensive there.

I will try the under cowl option, seems many have used this location, and as far as research on VAF, I have not seen a trend for antenna failures. Hopefully anyone who has experienced this will post their story. I guess time will tell.

Cheers
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  #9  
Old 03-04-2012, 08:02 PM
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My satellite antennas, 430W, 696, XM are all mounted under the cowl in a similar manners Jon described. All have worked perfectly for over 2 years now.
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  #10  
Old 03-05-2012, 05:32 AM
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Default Works well...

Never had a problem with mounting GPS antennas under the cowl.

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