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Internal Ant GPS under a t-top????

Old 11-24-2003, 06:31 PM
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Default Internal Ant GPS under a t-top????

I have a Garmin 182 chartplotter I have used it on a open CC, the boat is now having a t-top installed. Question is will the GPS still work?? Does anyone have a interal ant. GPS on a boat with a t-top
Thanks
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Old 11-24-2003, 07:25 PM
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Default Internal Ant GPS under a t-top????

I am running a Garmin 162 with internal antenna as a backup on my boat and it works fine.
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Old 11-25-2003, 05:12 AM
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Default Internal Ant GPS under a t-top????

I have two internal GPS antennas under a T-top, a Garmin and a Magelllan; both work fine. I have a canvas top, however.

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Old 11-25-2003, 05:14 AM
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Default Internal Ant GPS under a t-top????

When I upgraded my gps I took the antenna from up on top of the T-top and mounted the new one on the top of my console (under the the top). It works great.
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Old 11-25-2003, 09:46 AM
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Default Internal Ant GPS under a t-top????

Swindor.
I recently installed a 182c under my center console t-top. I tested the location with a hand held gps and all seemed fine. First trip out everything worked well. Since that time I lose the signal from time to time. Conclusion: It works petty well most of the time. Due to my desire to have a good signal all the time I have installed an external antenna. It now works great all the time. Go for the external setup.
Ron
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Old 11-25-2003, 10:36 AM
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Default Internal Ant GPS under a t-top????

A lot will depend on the height of the receiver relative to the t-top and the size of the top. Because of the weak signal they are pretty much line of sight antennas, so if you can see plenty of sky from the antenna location you should be fine. But if the top obscures much of the sky from the antenna location, you will want to think about an external antenna. I would give the antenna location the old eyeball test.

Also remember that the elevation mask will ignore signals from sats low in the sky - they are usually set not to use anything below 15-25 degrees above the horizon. So if this is adjustable on your receiver, you can set it lower. The atmospheric signal degradation will not hurt your accuracy enough to worry about and it will improve your ability to get a position lock.
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Old 11-25-2003, 12:45 PM
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Default Internal Ant GPS under a t-top????

Thanks for the info - I'll just have to try it when I get the boat back.

I guess there is no way to convert from Int. Ant to Ext. Ant. just buy a new unit, right??
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Old 11-25-2003, 01:58 PM
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Default Internal Ant GPS under a t-top????

I think you can buy an external antenna for the 182's.
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Old 11-25-2003, 05:59 PM
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Default Internal Ant GPS under a t-top????

I have a 182C with internal ant.. My question is how do remoce the internal ant and plug in the external. Do you just unscrew that piece in the back, and will that uncover the antenna jack?


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Old 11-25-2003, 06:12 PM
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Default Internal Ant GPS under a t-top????

I am doing the same thing as we speak. just take out the four screws holding the mount on. It wll come off and you will see the connector for the ant. we will just need to find out where to get a new mounting bracket. you you find one let me know where
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Old 11-25-2003, 06:31 PM
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Default Internal Ant GPS under a t-top????

thanks, I will


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Old 11-25-2003, 07:35 PM
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Default Internal Ant GPS under a t-top????

In general it will still work depending on the amount of metal/obstructions in the T-Top.

Will never be as reliable or efficent as an external antenna and if you use WAAS then it really has to be external.

quote:.... they are usually set not to use anything below 15-25 degrees above the horizon....

15-25 degrees No way.

Most recreational receivers are even less than 5 degrees right down to 0 degrees. Apart from the units, which allow a user definable mask there was/is one manufacturer that did have a 10 degree hardwired mask.

For user definable masks with this type of hardware certainly no more than 10 degrees and even in recent times dGPS sites world wide have actually lowered the mask from 7.5 degrees to 5 degrees.


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Old 11-26-2003, 09:44 AM
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Default Internal Ant GPS under a t-top????

lawyerdawg

looks like the swivel bracket they make for the garmin 182 will replace the internal ant. mount that you remove. Their web site says it is the only one that will work with the Ext. Ant. Check out the online store at www.garmin.com. I think am am going to try it
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Old 11-26-2003, 10:08 AM
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Default Internal Ant GPS under a t-top????

Kerry: you are undoubtably right about the elevation mask on marine rec receivers, which is why I was saying to set it that way. I use DGPS and RTK receivers that require cutting out low sats to make sure you are using common sats and that you get good elevations. But elevations and common sats aren't an issue with marine receivers or WAAS, so it makes sense that they are setup this way from the factory now.
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Old 11-29-2003, 12:20 AM
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Default Internal Ant GPS under a t-top????

To add the external antenna to the 182c you remove 4 screws on the back and take that part off. They have what amounts to a partial BNC connecter mounted in the back part which was held on with the four screws. Carefully pry the connector out of its location. You will see a small coax wire in which the shield is soldered to the outside of the connecter with the center wire soldered to the center.This is actually what connects your mini internal antenna. Unsolder and remove this coax. Strip back a little coax on your Garmin external antenna(got mine at Boatersworld for 99 bucks). Solder the shield where the other shield was and the center wire to where the center wire was. Next put a small notch in the part you removed with the four screws. This will provide a place for the coax to pass through when you put it back together. Make sure not to short the shield to the center conductor when you do the soldering. Press the part you soldered back into its original location. Using the 4 screws, reattach the back making sure the BNC parts mate when it gets tightened in place. That's it. Just did mine and get strong signals on 11 satelites as opposed to the 1-3 weak ones I got before.
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Old 11-29-2003, 02:53 AM
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Default Internal Ant GPS under a t-top????

Really one shouldn't have to "hack" an external antenna onto any unit.

Manufacturers simply should provide an external antenna connector on ANY unit. Like it's not all that difficult and certainly would provide users some simple and flexible options.

If a unit doesn't have an external antenna capability then it's something I wouldn't be bothered with in the first place.

Cheers, Kerry.

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