Avionics-List Digest Archive

Wed 11/28/07


Total Messages Posted: 13



Today's Message Index:
----------------------
 
     0. 12:29 AM - Wow! A Ton of Comments! (Matt Dralle)
     1. 02:52 AM - GPS Antenna Length (Wayne Sweet)
     2. 04:05 AM - Re: GPS Antenna Length (Richard T. Schaefer)
     3. 07:12 AM - Re: GPS Antenna Length (Paul Smith)
     4. 07:58 AM - Re: GPS Antenna Length (Wayne Sweet)
     5. 08:43 AM - Re: GPS Antenna Length (Mike Ferrer)
     6. 02:44 PM - Re: GPS Antenna Length (Wayne Sweet)
     7. 02:46 PM - Re: GPS Antenna Length (Wayne Sweet)
     8. 04:04 PM - Re: GPS Antenna Length (Vincent Palermo)
     9. 04:50 PM - Re: Re-GPS Antenna Coax Length (Mike Ferrer)
    10. 04:56 PM - Re: GPS Antenna Length (Richard T. Schaefer)
    11. 10:18 PM - Re: GPS Antenna (teamgrumman@aol.com)
    12. 10:38 PM - Re: GPS Antenna Length (teamgrumman@aol.com)
 
 
 


Message 0


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    Time: 12:29:20 AM PST US
    From: Matt Dralle <dralle@matronics.com>
    Subject: Wow! A Ton of Comments!
    Dear Listers, I've been getting a ton of great comments from Listers along with their List Support Contributions lately! I've shared a bunch more below. Please read over some of them and see what your fellow Listers think of the Lists and Forums. There are just a couple more days left before the official end of this year's Fund Raiser. Please make a Contribution today to support the continued upgrade and operation of these services. There are still lots of awesome gifts available, so browse the extensive selection and pickup a nice item along with your qualifying Contribution. http://www.matronics.com/contribution Thank you in advance for your generous support! It is very much appreciated! Best regards, Matt Dralle Matronics Email List Administrator ----------- What Listers Are Saying About The Lists ----------- In the big picture, you are most certainly saving lives. The fact that you do it at a very good level of service, quality, and simplicity is just icing on the cake. We all owe you a debt of gratitude. Bruce M Can't go a single day without reading my lists. Even when I am overseas. Terry W Best list ever. No comparison. Johann J I get the digest for the two lists I subscribe to each morning -- they go great with my coffee! I can't tell you how much I've learned from this great service... Mark S ..great lists, best on the Net! Robert S It is very nice to enjoy a SPAM free list. Ken L You run a great list. Makes a builder feel like there's lots of help out there for the asking, and it's appreciated. Steve T The list is a very valuable resource. Thomas S You run a good list. James G Thanks for a great forum. Jimmy Y Thanks for a well-maintained list(s). Michael M Great job! Worth every penny! Stephen T Helps me learn and think about issues I didn't know I didn't know. Martin H I find the list very useful... Robert F What you do provides me with daily contact with a passion of my life, aviation. Wendell M ..the list it is very valuable information. Dwayne H ..a great service to homebuilders. Andrew H I have learned quite a lot from reading the Forums. I have been reading at the forum pages and I like the way it works. Ron L [The List] makes a builder feel like there's lots of help out there for the asking, and it's appreciated. Steve T The list service many purposes, not the least of which is motivation to join my fellow RVer in completing my project and getting in the air. John S Thanks for running a great site. Its simplicity is its greatness. Don't know how I would have been successful without it. Timothy F ..terrific service to experimental and general aviation. James F You have a well run operation. I am happy to support what you do. Mark S A wonderful service to the GA community. David M Great list - let's keep it ad-free! Ben C They have been of great help, learning and friendship for all the members Worldwide. Great job of yours, a little idea that grew really big and wonderful. Gary G ..a thoroughly enjoyable and informative List. John W A GREAT LEARNING TOOL!! Dwayne Y This is a very well-run list and it is a valuable resource for the Pietenpol enthusiast. Graham H Thanks for running this great site - helps those of us on the east of the pond keep in touch. Malcolm H Thanks for the major contribution to my continuing education program. Oldbob S I'm just getting started in the building process & find Matronics to be the most valuable site. Scott D Without the information and encouragement from the listers my project would have been sitting in the corner of my shop collecting dust long ago. Now it's almost ready for final assemble and covering. Edward G Great List. No Ads, just RV-10 builders. Keep it going. Rick E Wonderful source of info for building & flying... Graham H The Yak-list is a superb single source to get answers to questions on the operation of these aircraft. Craig W This list is valuable to everyone and your hard work is very much appreciated. Jim S


    Message 1


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    Time: 02:52:50 AM PST US
    From: "Wayne Sweet" <w_sweet@comcast.net>
    Subject: GPS Antenna Length
    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


    Message 2


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    Time: 04:05:18 AM PST US
    From: "Richard T. Schaefer" <schaefer@rts-services.com>
    Subject: GPS Antenna Length
    I do not have the Install manual for the 430W or 530W. I do have the manual for Garnin 900 or the WAAS GPS conponent which is the GIA63W. The manual part number is 190-00719-00. The Install manuals are NOT on the Garmin Web site so you need to talk to a certified Garmin Installer to get the info. The manual states: Section 1.5 Wiring Considerations . RG400 or RG142 coaxial cable with 50 ohm nominal impedance and meeting applicable aviation regulations should be used for the installation. A typical maximum cable length for the GPS antenna is 40 feet. The installer should insure that the attenuation does not exceed 10 dB and falls between 3 dB and 7 dB inclusive at 1.5 GHz for the GIA63W. . I was told by a person who is certified for the 430W and 530W upgrades and installations that the above is also part of their manuals. As I mentioned earlier the spec is NOT a cable length spec but a loss requirement. You need to count the typical loss of two connectors and the coax cable loss itself. A 15 ft length of RG400 and good quality, properly terminated, connectors will place you near the 3DB minimum loss. They are REQUIRED to measure this! _____ From: owner-avionics-list-server@matronics.com [mailto:owner-avionics-list-server@matronics.com] On Behalf Of Wayne Sweet Sent: Wednesday, November 28, 2007 4:50 AM Subject: Avionics-List: GPS Antenna Length 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


    Message 3


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    Time: 07:12:35 AM PST US
    Subject: Re: GPS Antenna Length
    From: "Paul Smith" <paulsmith@torreengineering.com>
    My GNS480 Installation manual states: "The cable loss from the GPS antenna shall not be greater than 7 dB. If SatCom is installed on the aircraft, the cable loss shall be 3 dB minimum to ensure proper interference rejection from SatCom." I understand this to mean that since I don't have SatCom I can make the cable as short as I want. It is preesently about 6 ft. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=149115#149115


    Message 4


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    Time: 07:58:55 AM PST US
    From: "Wayne Sweet" <w_sweet@comcast.net>
    Subject: Re: GPS Antenna Length
    Exactly. Those are the older GPS's that the Garmin rep and NAVCOM referenced as needing the specific length. That GPS is no longer supported by Garmin and THAT is the reason the manuals are not on Garmin web site. The newer GPS's as I posted and as Garmin stated do not have those limitations. The statements from the "person who is certified" is NOT in accord with Eric at NAVCOM ( has installed WAAS's in certified aircraft) or the Garmin tech rep. Seems there is some disconnect here; I'm betting on Garmin and Eric at NAVCOM. For those interested, call Garmin; 913-397-8200. The "person who is certified" (by the way, that is any certified avionics technician, AND........YIIPPEEE any builder of an experimental aircraft) perhaps should call Garmin to get updated. Wayne ----- Original Message ----- From: Richard T. Schaefer To: avionics-list@matronics.com Sent: Wednesday, November 28, 2007 4:03 AM Subject: RE: Avionics-List: GPS Antenna Length I do not have the Install manual for the 430W or 530W. I do have the manual for Garnin 900 or the WAAS GPS conponent which is the GIA63W. The manual part number is 190-00719-00. The Install manuals are NOT on the Garmin Web site so you need to talk to a certified Garmin Installer to get the info. The manual states: Section 1.5 Wiring Considerations . RG400 or RG142 coaxial cable with 50 ohm nominal impedance and meeting applicable aviation regulations should be used for the installation. A typical maximum cable length for the GPS antenna is 40 feet. The installer should insure that the attenuation does not exceed 10 dB and falls between 3 dB and 7 dB inclusive at 1.5 GHz for the GIA63W. . I was told by a person who is certified for the 430W and 530W upgrades and installations that the above is also part of their manuals. As I mentioned earlier the spec is NOT a cable length spec but a loss requirement. You need to count the typical loss of two connectors and the coax cable loss itself. A 15 ft length of RG400 and good quality, properly terminated, connectors will place you near the 3DB minimum loss. They are REQUIRED to measure this! ------------------------------------------------------------------------- ----- From: owner-avionics-list-server@matronics.com [mailto:owner-avionics-list-server@matronics.com] On Behalf Of Wayne Sweet Sent: Wednesday, November 28, 2007 4:50 AM To: avionics-list@matronics.com Subject: Avionics-List: GPS Antenna Length 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 http://www.matronics.com/contributionhttp://www.matronics.com/Navigator?A vionics-Listhttp://forums.matronics.com


    Message 5


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    Time: 08:43:40 AM PST US
    From: "Mike Ferrer" <mike@ferrer-aviation.com>
    Subject: Re: GPS Antenna Length
    I have the Garmin GNS-430W installation manual, dated 11/2006, and this is what is says... "...Once the antenna mounting position has been prepared, route the coax cable from the antenna to the 400W Series unit. Proper selection of coax cable and assembly of connectors is critical to GPS signal performance. The cable loss from the GPS antenna shall be between 3 dB and 7 dB in order to maintain proper rejection to interference signals. The coaxial connectors and adapters, such as TNC to BNC, add additional loss to the cable and should be considered when computing the cable loss. A typical loss of 0.2 dB can be used for each connection. The typical cable loss for 20 feet of RG-142B or RG-400 coax with a connector on each end is 4 dB. For very short runs, where the loss is less than 3dB, additional cable should be used to increase the loss to within 3 dB to 7 dB. This additional cable may be coiled, taking into account the minimum bend radius of the cable..." I also have the Garmin STC Upgrade manual for upgrading existing 400/500 series to a 400W/500W series and it says the following... "...The 400W Series Installation Manual and 500W Series Installation Manual require that the coaxial cable have a loss of 3 dB to 7 dB. If RG400 is used, 3 dB equates to a length of approximately 13 feet of RG400 cable with a connector on each end..."


    Message 6


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    Time: 02:44:42 PM PST US
    From: "Wayne Sweet" <w_sweet@comcast.net>
    Subject: Re: GPS Antenna Length
    OK, that is correct apparently as of the date of the publication of that manual. According to the Garmin rep (a different guy this time) I spoke with today, a minimum of 6.5 feet is required for proper attenuation; "it was 13 feet" , again according to this rep. Did not ask when that change was made. He also did not mention any required maximum length; I should have asked. I was a bit shocked in his response in view of the first tech guy's response. So the point is, most installations will meet this new requirement unless the antenna is mounted on the glare shield directly above the GPS panel mount. I could have misunderstood the first rep in that my question was about a 13 to 15 foot required coax length; his answer was not complete apparently. Wayne ----- Original Message ----- From: "Mike Ferrer" <mike@ferrer-aviation.com> Sent: Wednesday, November 28, 2007 8:43 AM Subject: Re: Avionics-List: GPS Antenna Length > <mike@ferrer-aviation.com> > > I have the Garmin GNS-430W installation manual, dated 11/2006, and this is > what is says... > > "...Once the antenna mounting position has been prepared, route the coax > cable from the antenna to the > 400W Series unit. Proper selection of coax cable and assembly of > connectors > is critical to GPS signal > performance. The cable loss from the GPS antenna shall be between 3 dB and > 7 > dB in order to maintain > proper rejection to interference signals. The coaxial connectors and > adapters, such as TNC to BNC, add > additional loss to the cable and should be considered when computing the > cable loss. A typical loss of 0.2 > dB can be used for each connection. The typical cable loss for 20 feet of > RG-142B or RG-400 coax with a > connector on each end is 4 dB. For very short runs, where the loss is less > than 3dB, additional cable > should be used to increase the loss to within 3 dB to 7 dB. This > additional > cable may be coiled, taking > into account the minimum bend radius of the cable..." > > I also have the Garmin STC Upgrade manual for upgrading existing 400/500 > series to a 400W/500W series and it says the following... > > "...The 400W Series Installation Manual and 500W Series Installation > Manual > require that > the coaxial cable have a loss of 3 dB to 7 dB. If RG400 is used, 3 dB > equates to a length > of approximately 13 feet of RG400 cable with a connector on each end..." > > >


    Message 7


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    Time: 02:46:32 PM PST US
    From: "Wayne Sweet" <w_sweet@comcast.net>
    Subject: Re: GPS Antenna Length
    Just received this email from Garmin: Dear Wayne Sweet, Thank you for contacting Garmin International, The WAAS install manual requires a loss of 1.5 to 6.5 DB. 1.5 DB equates to about 6.5 feet of RG142B or RG400 with 2 connectors. With Best Regards, Walt Williams Field Service Engineer Garmin Aviation Product Support 913-397-8200 voice 913-397-8282 fax ----- Original Message ----- From: Wayne Sweet To: avionics-list@matronics.com Sent: Wednesday, November 28, 2007 2:50 AM Subject: Avionics-List: GPS Antenna Length 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


    Message 8


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    Time: 04:04:01 PM PST US
    From: Vincent Palermo <vpalermo@tampabay.rr.com>
    Subject: Re: GPS Antenna Length
    STC upgrade Installation Manual-400w/500/ Series Manual Number 190-00357-06 Page 9 Rev. B In paragraph 2.5.4 the following notes are inserted the 400W series installation manual and 500W series installation series manual require that the coaxial cable have a loss of 3 db th 7 db. If RG400 cable is used, 3 db equates to a length of approximately 13 feet of RG400 cable with a connector on each end. To maintain integrity of the WAAS signal, the GPS antenna coaxial cable must have a minimum of two shields(E.G. RG400 OR RG142B). IF THE EXISTING COAXIAL CABLE IS SINGLE SHIELDED(E.G. RG58 OR RG59), THE ENTIRE CABLE MUST BE REPLACED EVEN IF IT MEETS THE OVERALL CABLE ATTENUATION REQUIREMENT. If the existing coaxial cable is terminated with a BNC connector and the GPS WAAS antenna being installed has a TNC connector, a TNC-to BNC adapter such as P?N 1-1478013-0 from AMP (Tyco) may be used. The adapter will add 0.5 db to the overall GPS antenna cable loss. 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 done them all. 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 > >


    Message 9


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    Time: 04:50:27 PM PST US
    From: "Mike Ferrer" <mike@ferrer-aviation.com>
    Subject: Re: Re-GPS Antenna Coax Length
    So, I guess we can all agree, there IS a requirement for coax loss (i.e., coax length) although it sounds like they reduced the minimum from 13' to 6.5'. ----- Original Message ----- From: Wayne Sweet To: avionics-list@matronics.com Sent: Tuesday, November 27, 2007 5:12 PM Subject: Avionics-List: Re-GPS Antenna Coax Length When in doubt, go to the front end of the horse. Straight from the "horse's mouth" (Garmin installation tech rep 913-397-8200); there is no requirement for either the GNS430 or GNS530W minimum or maximum coax cable length. Wayne


    Message 10


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    Time: 04:56:17 PM PST US
    From: "Richard T. Schaefer" <schaefer@rts-services.com>
    Subject: GPS Antenna Length
    You will be able to get away with just about anything for enroute GPS nav and VFR approaches. If you expect to use the GPS for the new precision approaches, and you do not want them flagged while you are still in the soup, you would be best served to follow all of the little details in the installation manual. Including those that talk about required DB loss in the GPS antenna path (needed for WAAS integrity), location of COM cabling and antennas in relation to GPS antennas, (Limit cross interference when communication while on approach), and potential low angle shadowing of airframe components between the GPS antenna from GPS satellites. _____ From: owner-avionics-list-server@matronics.com [mailto:owner-avionics-list-server@matronics.com] On Behalf Of Vincent Palermo Sent: Wednesday, November 28, 2007 5:57 PM Subject: Re: Avionics-List: GPS Antenna Length STC upgrade Installation Manual-400w/500/ Series Manual Number 190-00357-06 Page 9 Rev. B In paragraph 2.5.4 the following notes are inserted the 400W series installation manual and 500W series installation series manual require that the coaxial cable have a loss of 3 db th 7 db. If RG400 cable is used, 3 db equates to a length of approximately 13 feet of RG400 cable with a connector on each end. To maintain integrity of the WAAS signal, the GPS antenna coaxial cable must have a minimum of two shields(E.G. RG400 OR RG142B). IF THE EXISTING COAXIAL CABLE IS SINGLE SHIELDED(E.G. RG58 OR RG59), THE ENTIRE CABLE MUST BE REPLACED EVEN IF IT MEETS THE OVERALL CABLE ATTENUATION REQUIREMENT. If the existing coaxial cable is terminated with a BNC connector and the GPS WAAS antenna being installed has a TNC connector, a TNC-to BNC adapter such as P?N 1-1478013-0 from AMP (Tyco) may be used. The adapter will add 0.5 db to the overall GPS antenna cable loss. 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 done them all. 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


    Message 11


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    Time: 10:18:21 PM PST US
    Subject: Re: GPS Antenna
    From: teamgrumman@aol.com
    I talked to a tech/engineer at Garmin. =C2-The spec has been changed to a minimum of 1 1/2 db loss=C2-(there is that much loss in a 90 degree adapte r.), maximum of 6 db. -----Original Message----- From: Vincent Palermo <vpalermo@tampabay.rr.com> Sent: Tue, 27 Nov 2007 4:18 am Subject: Re: Avionics-List: GPS Antenna I believe that Garmin is=C2-referring=C2-to the waas upgrades for the 43 0/530 series. It also requires that you use double shielded wire, RG-142 or Rg-400. You are right about the short cable length for the 430 and the sl-60 , it will work, and so will the gps map series work with a short antenna cab le. Also Garmin specs are between -3 and -7 db loss, I wonder if they would approve some kind of impedance matching device in the line??????? Vincent Palermo vpalermo@tampabay.rr.com On Nov 27, 2007, at 12:55 AM, teamgrumman@aol.com wrote: I have both a Garmin 430 and an Apollo SL-60 with antennas mounted about 12 to 15 inches away. =C2-Both work fine with no signal loss. =C2-I've flow n all over the country with them. =C2-Maybe I'm getting a 3db loss through the plexiglass windshield. -----Original Message----- From: Noel R. C. Loveys <noelloveys@yahoo.ca> To: avionics-list@matronics.com Sent: Mon, 26 Nov 2007 9:53 am Subject: RE: Avionics-List: GPS Antenna The received signal is digital.=C2- This means it only receives 1s and 0s. =C2-If the signal is too strong (cable shortened) everything looks like a 1.=C2- If the signal is too low ( cable lengthened) everything looks like a 0.=C2- Either way no data is received. =C2- I guess the folks at Garmin knew what they were doing when they wrote the in stallation instructions.=C2- Loop the excess wire in as large a loop as pr acticably possible.=C2- Try to avoid bundling with Xmtr. Coax. =C2- Noel =C2- =C2- From: owner-avionics-list-server@matronics.com [mailto:owner-avionics-list-s erver@matronics.com] On Behalf Of teamgrumman@aol.com Sent: Monday, November 26, 2007 5:02 AM To: avionics-list@matronics.com Subject: Avionics-List: GPS Antenna =C2- I've been trying to find an acceptable answer as to why Garmin wants to have the coax cable for the=C2- GPS antenna to be between 13 and 15 feet.=C2- If I can mount an antenna ju st 15 inches away from the=C2- unit itself, why do I need to mount the antenna 15 feet away?=C2- =C2- One explanation I got was the 430/530 needed a 3 db loss in the cable.=C2 - Now, it seems to me that the stronger the signal at the unit is, the better. =C2- For what it's worth, I mounted my antenna (Garmin 430) on the glareshield on my Tiger. That was 4 years ago.=C2- I've never had any problems with losing the sign al.=C2- I'm installing another 430 and was told the 430 won't work with a 15 inch cable.=C2- =C2- Any ideas? Email and AIM finally together. You've gotta check out free AOL Mail! =C2- =C2- http://www.matronics.com/contribution http://www.matronics.com/Navigator?Avionics-List http://forums.matronics.com =C2- ution">http://www.matronics.com/contribution or?Avionics-List">http://www.matronics.com/Navigator?Avionics-List p://forums.matronics.com Email and AIM finally together. You've gotta check out free AOL Mail! href="http://www.matronics.com/contribution">http://www.matronics.com/cont ribution href="http://www.matronics.com/Navigator?Avionics-List">http://www.matroni cs.com/Navigator?Avionics-List href="http://forums.matronics.com">http://forums.matronics.com ________________________________________________________________________ .com/cdn.webmail.aol.com/mailtour/aol/en-us/text.htm?ncid=aolcmp0005000000 0003


    Message 12


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    Time: 10:38:32 PM PST US
    Subject: Re: GPS Antenna Length
    From: teamgrumman@aol.com
    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 l ine is that this is how I have installed dozens of WAAS upgrades since Garmi n came out with the upgrades and this is how we have done them all." Question: =C2-When you say, "The bottom line is that this is how I have in stalled 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 li st references. Both NAVCOM is Visalia, Ca and Garmin tech rep say no such CU RRENT requirement exists. Older Garmin GPS's did require such attenuation in the coax; not now. Wayne http://www.matronics.com/contribution href="http://www.matronics.com/Navig ator?Avionics-List"http://www.matronics.com/Navigator?Avionics-List href=" http://forums.matronics.com"http://forums.matronics.com ================== ________________________________________________________________________ .com/cdn.webmail.aol.com/mailtour/aol/en-us/text.htm?ncid=aolcmp0005000000 0003




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