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Suunto x9i GPS External Antenna Modification
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(jhaura) - F

Locale: Trail
Suunto x9i GPS External Antenna Modification on 04/19/2007 14:28:34 MDT Print View

Poor antenna design on x9i, so I hacked it up and added an external antenna jack and made my own removable SUL external antenna.

I used MMCX connectors and 24awg bare wire cut to exactly 1/2 GPS radio wavelength (190mm or 7.48 inches).

Now I get 4-5 bars, 7-9 sats and 1M estimated error INDOORS! Outside it is awesome. It acquires faster and locks better.

I works better than other analog GPS's I've tried against known waypoints. Equally accurate but better performance.

This may be the smallest and lightest navigation based GPS out there. (Note: forerunners with sirf don't have baro, or mag compass)

I'm surprised it still works as I am not trained in any electrical stuff. I'm crazy when it comes to tinkering and I got a good deal on this ($89), so I was not too worried about crashing it.

Unit weight: 1.54oz
Antenna weight: 0.03oz

Total weight: 1.57oz

Here's some pics (shown with wristband removed, which I don't use anyway):

Unit and antenna.


Indoor use (when I leaned over it to take the picture I blocked some signal, so full bars are not showing).


Close up of connectors.


Sorry for the poor quality pics, but my good camera got dropped.

Edited by jhaura on 04/19/2007 14:30:15 MDT.

Steve .
(pappekak) - F

Locale: Tralfamadore
Re: Suunto x9i GPS External Antenna Modification on 04/19/2007 14:32:44 MDT Print View

Very cool. Not brave enough to try that with my Geko. How did you figure out which wire to connect the jack to?

Edited by pappekak on 04/19/2007 14:39:05 MDT.

christopher witter
(cwitter) - MLife

Locale: Mid Atlantic
Straight up, Dope! on 04/19/2007 19:25:23 MDT Print View

Wow! That has to be the slickest mod I have seen yet! For someone who claims to not be into electronics that is no simple feat! How about some more info/details on the mod? How did you determine the wave length, etc? Anyway you can provide some close ups of the internals?

Harry Ervin
(Specopsscout) - F
Suunto x9i GPS External Antenna Modification on 05/13/2007 21:11:22 MDT Print View

Hey Brother,
Here's one more pleading request for a detailed breakdown of exactly what you did and how you did it. I'd really like to see my watch perform like that!
Thanks for the post and I look forward to additional information.

(jhaura) - F

Locale: Trail
Re: Suunto x9i GPS External Antenna Modification on 05/13/2007 21:17:34 MDT Print View

Harry et al,

Ok I will try and give more beta and pics soon. Just check the watch this thread option at the top of the thread and you will be notified by email when a new post is made. So sooo busy, but I'll do my best.

BTW, I made some changes to the antenna and connector and now receive even better reception and performance. I'll include those details in the update.

Thanks for the posts!

Harry Ervin
(specopsscout) - F

Locale: Eastern Seaboard
Suunto x9i GPS External Antenna Modification on 05/15/2007 08:52:31 MDT Print View

Hey Brother,
Will do! Even better performance then the initial post? You've got me glued to this thread...

Harry Ervin
(specopsscout) - F

Locale: Eastern Seaboard
Suunto x9i GPS External Antenna Modification on 05/21/2007 14:18:44 MDT Print View

Hey Brother,
Standing by for the stand by. ;)

James Panzitta
(gpop1) - F
Re: Suunto x9i GPS External Antenna Modification on 05/27/2007 20:34:53 MDT Print View

Hi Jhaura,
When you connected the MMCX female connector did you just solder to one side of the existing loop antenna and just add the 7.5 inch external antenna or did you disconnect both sides of the internal loop antenna from the terminals?

I am waiting to receive my Suunto X9i watch next week. I would like to make the modification. I have an external GPS antenna with a male MMCX connector. I was going to try improving the signal by induction. I was going to connect a 7.4 inch loop of wire to the end of the MMCX connector of the GPS antenna and place it over the existing loop antenna in the watch to see if improves the signal.

Please let me know how you hard wired the antenna to the
X9i or your latest improvement for a stronger GPS signal.

Suunto has a video that shows how to replace the bezel ring of the watch and the loop antenna is exposed so you can easily attach an external antenna.

(jhaura) - F

Locale: Trail
Re: Re: Suunto x9i GPS External Antenna Modification on 05/27/2007 22:25:14 MDT Print View


The induction method would be a great start before hacking up your new watch. Remember, I only paid $89 for mine.

I have found that the left side of the loop antenna accepts the inducted(?) signal better nearest the point where it enters the case. (my sodered on mmcx connector only attaches to the left side of the antenna jack in the watch. I found the right side to be worthless). The left side would be just after the word "DATA" on the "START DATA" button. Try removing the bezel and strap and place your connector touching the copper at that point. Fish around a little for signal improvements. Try a piece of 24-26 awg copper wire (like from an old cat3/cat5 cable) cut to length first, straightened out and then try your antenna. I'd be curious if the gps antenna did any better than just the simple copper wire cut to 7.48 inches. Strip alittle of the insulation off at the ends about 1/8" or use bare copper.

I'm trying to get some time to post more info and pictures.

ulf Pindurs
(pindurs) - F
More details? on 08/26/2007 13:33:24 MDT Print View

I'm surprised by the poor reception of the X9i, it's not very practicle to use it in a town, although it would be quite useful sometimes, for example to find back your car or your hotel.
When I'm standing 10 minutes in a corner with my wrist over my head, nobody looks at me, which shows that they probably think I'm crazy...

I tried the "soft" mod, by only connecting a 190mm wire to the left side, without soldering.
It's improving the reception of the satellites, no doubt, but I was expecting more.

Jhaura, could you give some more details? Your mod looks like voiding the Warranty, but maybe it would be worth trying it.

What is the other improvement you did? did you disconnect the copper wire and directly connect your antenna?

Thanks in advance for your answer.

eric DUDU
(FreeR1965) - F
Suunto X9i improvement on 02/03/2011 14:12:12 MST Print View

Hi Jhaura,

I just buy my X9i and I have seen the same poor antenna quality for the GPS. I want make the same modification as you have done. Can you give me more details about how to connect and where to connect your add-on antenna.

Do you have some photographies or drawings about this ?

I hope I could modify my watch as you have done to get the best of this nice jewel.