GTN 750 GPS Antenna Length Requirement?

[CharlieWaffles]

I came across this old thread that detailed that Garmin spec'd a minimum of 13' for the GPS Coax antenna cable. I don't see any requirement in the gTN 750 install manual, but I'm wondering if this is still a common practice that is followed.

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[Radomir]

It had been removed from GNS requirements too.. it was a requirement in first iteration, but has been removed for years now (ie not applicable to 530/430 either)..

[Brantel]

In the 750 install manual I am looking at, Rev 2, page 3-4 details the requirements. 1.5 to 6.5dB loss required so 6.5' with connectors would do it.

The following line has been edited:
The 430W manual I have, Rev F, shows em on page 3-9. 3-7dB loss required for Table 1-3 antennas so 13' would do it with connectors. Table 1-2 antennas require 1.5 to 6.5dB loss required so 6.5' with connectors would do it.

[g3xpert]

Originally Posted by Brantel

In the 750 install manual I am looking at, Rev 2, page 3-4 details the requirements. 1.5 to 6.5dB loss required so 6.5' with connectors would do it.

The 430W manual I have, Rev F, shows em on page 3-9. 3-7dB loss required so 13' would do it with connectors.

Brantel,

You are correct that the GTN 750 antenna cable requirement is minimum 6.5' to acheive the minimum cable loss of 1.5 db. This cable length requirement is applicable to the antennas listed in section 3.1.1 of the GTN installation manual. Basically the GA 35/36/37 are the listed antennas. Table 1-3 (page 1-9) in the GTN installation manual lists some other antennas that will work with the cable loss requiements you noted on page 3-4.

The GNS 430W manual has the same cable length requirements as the GTN when one of these three GA 35/36/37 antennas are used. Also there are three Comant combination GPS/WAAS+VHF antennas listed in table 1-2 (page 1-9) in the GNS 430W installation manual that would work. There is a note on page 3-9 for antennas listed in table 1-3 (page 1-10) that still do require the 13' antenna cable length though (cable loss between 3 db and 7 db). These are some of our older WAAS antenna models listed in table 1-3 in the GNS 430W installation manual.

The antennas listed in table 1-3 in the GNS 430W installation manual are not listed as usable with the GTN 750 in its installation manual any where. That is why the GTN 750 installation manual only shows the 6.5' cable length cooresponding to the 1.5 db minimum cable loss requirement.

Hope this helps

Garmin Tim

[Brantel]

Tim,

Thanks for clarifying. I missed the notes on the 430W. Edited my prior post to clear that up.

[Daniel S.]

Shouldn't you just be able to line up the TSO requirements? The antenna for the GTN750/650 for GPS & comm TSO C37 & C38... vor,loc & GS should meet TSO C40,C36 & C34 per the manual Or NON-TSO'd equivents of course