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0. 12:14 AM - [Please Read] - Last Official Day of List Fund Raiser! (Matt Dralle)
1. 12:14 AM - Re: GPS Antenna Length (teamgrumman@aol.com)
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| Subject: | [Please Read] - Last Official Day of List Fund Raiser! |
Dear Listers,
Its November 30th and that means a couple of things. Its my 44th birthday for
one, but I'm trying to forget about that... But, it also means that its that
last official day of the Matronics Email List Fund Raiser!
If you been drooling over one of the really sweet free gifts that are available
this year with a qualifying Contribution, then now is the time to jump on one!!
If you've been meaning to make a Contribution, but just keep putting it off, then
now is the time!
I will be posting the List of Contributors in a few days, so you'll probably want
to be known as a person that supported the Lists! Rather than the guy that,
er, ah, forgot (or whatever)... :-)
I want to thank everyone that has so generously made a Contribution so far this
year in support of our Lists. It is your generosity that keeps this operation
a float and I don't ever forget it. Hopefully everyone will feel the same.
The List Contribution page is fast and easy. Please support our habit by making
your Contribution right now:
http://www.matronics.com/contribution
Thank you all in advance!
Matt Dralle
Matronics Email List Administrator
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| Subject: | Re: GPS Antenna Length |
What you say has some merit. =C2-And, in the ideal world, the engineers id
ea of a generic installation fits all applications. =C2-In the ideal world
, the best place to mount the GPS antenna is always on the top of the plane.
=C2-In the real world, my experience with the FAA and certifying STCs has
taught me that the only way to get something certified is to write installa
tion instructions so that any idiot can install the STC and the installation
will work. =C2-In most cases, that is sufficient.
However. =C2-This is not always the case. =C2-For example: =C2-Install
ation on Grumman-American aircraft
(1) The turtle-deck on a Lynx/Traveler/Cheetah/Tiger isn't horizontal in fli
ght. =C2-
(2) If mounted on the turtle-deck, about 180 degrees of forward horizon is b
locked
(3) The GPS antenna cannot be mounted on the canopy. =C2-
(4) The location of the comm antenna on the=C2-turtle-deck=C2-
=C2-=C2- =C2- and mounting the GPS antenna 2 feet away from the antenn
a,=C2-
=C2-=C2- =C2- puts the GPS antenna either right under the canopy when
it's open or
=C2-=C2- =C2- alongside the dorsal fin near the vertical stabilizer wh
ere it is blocked. =C2-
So, the solution: mount the GPS antennal on the glareshield. =C2-This resu
lts in
(1) The GPS antenna being horizontal in flight
(2) The GPS antenna being visible to the horizon about 300 degrees horizonta
lly
(3) The GPS antenna being visible to the sky about 160 degrees vertically
True, the GPS antenna doesn't see all of the horizon or all of the sky, but.
=C2-I've had really good performance with my GPS antennas mounted on the
glareshield.
Most people are happy to blindly follow any instruction given them and care
nothing about why (or how) the instructions came to be. =C2-After doing ba
sic research in combustion instabilities for=C2-22 years, I've become accu
stomed to not accepting 'that's-how-we've-always-done-it' as an answer.
I asked the question, and called Garmin, because I wanted to know the answer
. =C2-I wanted to know if the GPS unit would really fail / burn-up / explo
de / decapitate / melt / make the wings fall off / =C2-or whatever, if the
antenna were mounted anywhere but where the instructions say. =C2- I was
told by Tim, at Garmin, that he'd rather see the antenna mounted on the glar
eshield (so that it could see more of the horizon) than on the turtle-deck a
t 7 to 10 degrees from the horizontal. =C2-He suggested coiling up 6 feet
of cable to get 1 1/2 db loss. =C2-The next step is to investigate what th
e total loss in the cable actually is (at various lengths) with BNC/TNC conn
ectors. =C2-1 1/2 db is easy.
-----Original Message-----
From: Charles Reiche <reichec@verizon.net>
Sent: Thu, 29 Nov 2007 4:03 am
Subject: Re: Avionics-List: GPS Antenna Length
When Mr. FAA man comes and signs my paperwork, I am
certifying that I have installed the device PER THE MANUAL; and the manual
says=C2-I need to install a certain length of coax with a certain value of
attenuation between point A and point B, I legally have to follow what it sa
ys
in the manual...=C2- Becuase when some moron crashes flying beyond his
capabilities below minimums, and his wife comes to sue our shop, I need to
assure that I have done my job 100%....=C2-=C2- The only time I ever dev
iate
from what the installation manual says is when I have information from Walt
Williams or George Koelch or one of the other garmin tech guys,=C2- AND wh
en I
install it PER THE MANUAL and for some reason it doesnt work right for a cer
tain
application in a certain airplane, then and only then do I modify what the
install manual says and I attach info that I recieve to my work order and It
lives on forever in my files at our repair station.=C2-=C2- I dont
understand the mentality of "how cheap can I be" by using the wrong coax or
coax
is too short... Is it reall that hard to install it per what the manufacture
r
says in their publications?=C2- 99.99% of the time it works... so why are
we
questioning what they are saying?
=C2-
----- Original Message -----
From:
teamgrumman@aol.com
Sent: Thursday, November 29, 2007 1:37
AM
Subject: Re: Avionics-List: GPS Antenna
Length
Quote "THERE IS A LOT MORE THAT THE MANUAL STATES, BUT MY
TYPING IS SORT OF LIKE WATCHING PAINT DRY AND MY INDEX FINGERS ARE GETTING
TIRED. The bottom line is that this is how I have installed dozens of WAAS
upgrades since Garmin came out with the upgrades and this is how we have d
one
them all."
Question: =C2-When you say, "The bottom line is that this is how I have
installed dozens of WAAS upgrades since Garmin came out with the upgrades
and
this is how we have done them all."
------ so, to what method do you refer?
Vincent Palermo
vpalermo@tampabay.rr.com
On Nov 28, 2007, at 5:50 AM, Wayne Sweet wrote:
For those who assert that there is a minimum
WAAS GPS coax length, please list references. Both NAVCOM is Visalia, Ca
and
Garmin tech rep say no such CURRENT requirement exists. Older Garmin GPS
's
did require such attenuation in the coax; not now.
Wayne
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