QX7S and LR12

General Help and support for the Taranis Radio.
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StuartMunro
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QX7S and LR12

Post by StuartMunro »

Hi,

A newbe to Open TX/ FrSky. I sail boats and 2.4ghz has limited range over water. I would rather not go for a 868mhz module but was interested in the extended range 2.4ghz receiver which may add a bit to my range. However it appears that the QX7S ACCESS no longer has LR12 mode. I can add a module but would rather have 'on board' LR12.

Can I achieve this?

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Kilrah
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Re: QX7S and LR12

Post by Kilrah »

Have you looked to see if you can actually find L9Rs in the first place? It was discontinued years ago.

If I remember well the "classic" QX7 has LR12, just not the new ACCESS version.
StuartMunro
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Re: QX7S and LR12

Post by StuartMunro »

Yup - T9 hobby have them at £32.76.

And you are right re classic having LR12 and not ACCESS. I could buy a module (XJT LBT) which does not show LR12 anymore byt T9 have assured me it is LR12 capable. But I would rather get LR12 on my QX7S Access if that is possible.
StuartMunro
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Joined: Sat Jul 17, 2021 7:22 am
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Re: QX7S and LR12

Post by StuartMunro »

Water and 2.4Ghz don't mix. I believe its because those TX signals that hit the water are either absorbed or reflected and the reflected signals are corrupted by the reflection. This creates noise which hurts higher frequency signals more than lower ones. In practice us 'sailors' get 200 meters or more on a good day. Antenna placement becomes very critical (I suspect more so than with aircraft) so I was hoping that the improved gain of the L9R might add a bit to the range.

Personally I am looking for 350-400 meters to cover the whole lake.

I'm going to try a redundancy receiver with 2 more antenna placed differently; 1 parallel to the boat, one across the boat and 2 angled down so that as it keels over one of the 2 becomes horizontal.
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Kilrah
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Re: QX7S and LR12

Post by Kilrah »

It's not possible to use it without a module, you have to use an XJT or other compatible one like the multiprotocol module.

Since you need to get a module you might as well forget 2.4GHz and get a 868 one which might be a lot more appropriate.

StuartMunro
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Re: QX7S and LR12

Post by StuartMunro »

Kilrah,

Thanks for the thoughts. I can see that the 868 mhz frequency is a lot less susceptible to being near water but we boat builders are an irrational lot. We like our boats to look realistic close up which means the antenna are mounted within the hull. Take a look next time you see one - even RTR plastic speed boats from hobby stores have the antenna inside the hull.

This is possibly just about the worst place to put them but we are careful to keep them above the waterline and at least prefer to use wooden hulls, which are radio transparent.

So my fear about the rigid and large 868mhz antenna is that they can not easily be mounted inside the hull. I'd be delighted if you tell me I'm wrong on this as I've looked at both Frsky M9 and TBS Crossfire systems either of which will almost certainly solve range problems.

Also cost becomes a factor; I doubt that I could solve range for one boat so would be looking to re equip 4 or 5. Which a module £200 - £250 (Frsky M9) or more (TBS Crosssfire)
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Kilrah
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Re: QX7S and LR12

Post by Kilrah »

Both of these have small antennas you can leave inside the hull. Obviously not as ideal than having them outside, but still likely better than 2.4 given the lack of interaction with water 2.4 has.

Best would probably be to borrow some gear and see if it's appropriate before buying...
StuartMunro
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Re: QX7S and LR12

Post by StuartMunro »

Kilrah,

We're all wrinklies at my club. No one has 868 and those who also fly never fly long range so also no 868.

But I love tinkering so will probably 'invest' in the Frsky R9M system - a basic set up will cost about £70 - can add other boats later if it works.

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