Today's Message Index:
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1. 01:08 PM - TCAS ground plane (Strasnuts)
2. 09:13 PM - New Bose (David Leikam)
3. 10:50 PM - Re: New Bose (Tim Olson)
Message 1
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| Subject: | TCAS ground plane |
Thought I would share my experience installing a ground plane on the RV-10 cabin
top for the GTS800 and hopefully save some building time for others. Like every
other Garmin device, the installation manual gives you a detailed list of
priorities for mounting and location of antennas. Some items, such as the GMU44
would only meet all the criteria if it was mounted to a 20 foot rigid line hanging
off the plane. My experience with Garmin is they are extremely sensitive
units. This is great for operation but tough for installation. The GTS800 is
no different. The first location priority is to mount the top GA58 antenna on
the highest and most forward location on the aircraft with no antennas in front
of it. It has to be mounted level and in the middle. OK so far so good. Next
it needs an 18 x 18 ground plane. WHOA. We have roughly a 10 x 30 spot on the
top between the doors hinges. I have the sweet Aerosport overhead console installed
and it has the 10 x 30 dimensions inside. I came to the conclusion I could
use a copper wire mesh inside the overhead console with a backing plate.
The ground plane should see through the honeycomb and fiberglass. I could get
the square inches needed but not the 18 x 18 width. I also mounted a bottom monopole
antenna for the TAS so there will not be any shadowing from the fuselage.
This is a simple transponder blade mounted right below the GA58. BTW the top
requires 4 coax and the bottom requires 1. I then powered up the plane, configured
the GTS800 to talk to the 430w and 330es. Check the self test on the TAS
and "FAILED" shows up.
The configuration program is a downloadable exe. for windows that hooks to the
GTS800 via USB connection. You can configure all the settings and diagnose problems.
There is also an assert file you can save as a txt file and email to Garmin
for troubleshooting. Mine returned with a "receive cal" fault, which translates
to coax or/and antenna ground plane. I was pretty confident with my coax
crimping abilities and really believed it was the ground plane size. After a
few attempts of backing plates and wire mesh combinations I finally tried placing
a 20 x 20 scrap sheet of .016 to the top of the cabin. Obviously this is
overhanging the doors and is only for testing purposes. The self test passed with
the giant ground plane on TOP of the cabin. After trying different sizes on
the top and the bottom it was very apparent that I HAD to have a ground plane
on the top of the cabin under the GA58. I don't know how Cirrus does it but
their new planes show the GA58 on the top between the doors. Their span is even
narrower than the RV-10. They must use a mesh inside the glass or carbon fiber.
Just a 10x 18 span of aluminum tape on the top of my cabin worked great. BTW
I also tried grounding the ground plane to the airframe and that had no affect
on passing or failing the self test. I also wrapped aluminum tape from the
inside ground plane/backing plate through the coax hole and made a footprint
of the antenna out of the aluminum tape. I left this on.
I called Garmin and they said to move the antenna to the tailcone area. This wasn't
an option for me. #1 it's not level, #2 my two gps antennas are already there,
#3 too close to my GMU44, #4 too far back on the plane, #5 not inline with
the bottom antenna anymore.
After knowing I had to make a ground plane on the top of the cabin, I slowly cut
it down in size to see how small I could make it while still passing the self
test. I eventually ended up with a 6 x 18 piece of .025 aluminum. I wanted thicker
than .016 so it wouldn't de-laminate from the cabin. Before I attached
it I ran the self test. It passed. I then wanted to epoxy it to the cabin top
and glass over it with a few sheets of fiberglass. I drilled the rivet holes for
cs4-4's and ran the test.....FAILED. WTH??? I thought it was a mistake and
ran it again....FAILED. I couldn't believe it was the rivet holes so I temporarily
taped over them with the aluminum tape......PASSED! Just the open holes caused
the antenna to fail consistently. I thought the rivets in the holes would
cure it and they did. I now have a glassed over ground plane 6 x 18 on the top
of the cabin and it has worked flawlessly for 12 hours now. I still don't know
why the ground plane doesn't work inside the cabin. It must be a distance
from the antenna deal but I tried everything inside.
This is also a good example why I didn't paint my plane before my first flight:)
Attached is a photo of two layers of glass. I put down one more and feathered
it in.
--------
Cust. #40936
RV-10 SB Fuselage
N801VR reserved
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=336856#336856
Attachments:
http://forums.matronics.com//files/photo_822.jpg
Message 2
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For those flying with the new Bose who have used the old ones, how much better
are the new ones?
David Leikam
RV10
Flying
Message 3
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Dave, if you've flown with the old and find them completely comfortable and quiet,
the A20's will just be a step up in both but I can't say it's a huge step
up or anything. It's a noticeable difference in quiet, but truthfully the old
X's were plenty quiet. You should really just fly with both or at least the
one you want to buy first, because fit and comfort is of utmost importance. The
biggest difference for me personally is that the A20 ear cups are a bit larger,
so my ears flop in comfortably easier. If you use the X's and find no fit
issue at all, then you probably would like either. If you plan to get 4, you
could do a mix for front and back seats and you're unlikely to have people complain.
You're basically asking "hey, you porsche and Ferrari owners out there...how much
better is a top of the line Ferrari over a top of the line Porsche?". Either
one will make most drivers happy.
I like them both....but I like the A20's just a little more.
One other positive is that it's much easier and cheaper to adapt a Lemo plug a20
to standard jacks with an adapter....so if that interests you, I'd go A20.
The biggest downside is that my X's I could leave powered on all the time and
they'd stay on. The A20's I have to hit the power button to turn on every flight.
The only other major/minor difference is if you plan to use the Bluetooth or music
input.....but most people will do that on their audio panel (the music at
least) anyway.
I'm halfway through my latest trip write up and I mentioned the a20's since this
was the first long trip with them. You'll see that in a couple days when I
can finish typing.
Tim
On Apr 13, 2011, at 11:10 PM, David Leikam <daveleikam@wi.rr.com> wrote:
>
> For those flying with the new Bose who have used the old ones, how much better
are the new ones?
>
> David Leikam
> RV10
> Flying
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