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Old Oct 26, 2007, 09:20 AM
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2.4Ghz JR DSX9 UK TX Question

What should I do. I want a new TX and the one that I like is the JR PCM9XII. Now as everybody seems to be getting 2.4Ghz and me being a lemming I want the 2.4Ghz one called the DSX9 (Out soon!).

The trouble is as most Americans know everything in Europe is small including the power output which appears to be reduced from the US version.

Extract from MacGregor site

Quote:
The X9303 version that is now available in the USA is allowed up to 500mW of RF with an effective radiated power (ERP) of 1W. (The ERP takes into account the gain of the antenna fitted). The European version must abide by the European regulations (EN 300-328 ) which limits the power output to 100mW ERP but because the Spektrum DSM system uses Direct Sequence Spread Spectrum a limitation of a Power Spectral Density not exceeding 10mW/MHz also applies.

What effect this will have as a direct comparison between the US version and the UK version is at the moment unknown but anticipate a reduction in range.
What I want to know in plain speak, if anybody knows yet is will the UK version of the JR 2.4Ghz be suitable for gliders or should I stick with good old fashioned technology.

Many thanks
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Old Oct 26, 2007, 09:09 PM
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Interesting, we are about to get the DSX9 in Australia soon also. I wonder what the power level will be for ours? I suspect for those in the know it will be a simple tweak inside to alter power output.
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Old Oct 27, 2007, 01:21 AM
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My understanding was that to pass UK/Europe type approval you must not be able to change it with a simple tweak. This may of course be nonsense and I dreamt it. The second problem in the UK was that using a tx that was not legal invalidated your insurance, otherwise I would have imported a US one.
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Old Oct 27, 2007, 02:39 AM
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Quote:
Originally Posted by cmyers_uk
...
What I want to know in plain speak, if anybody knows yet is will the UK version of the JR 2.4Ghz be suitable for gliders or should I stick with good old fashioned technology.

Many thanks
2.4GHz works great, but not with reduced power. If you want to use 2.4GHz in Europe, go for Futaba FASST.

Jürgen
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Old Oct 28, 2007, 02:10 AM
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100mW is still the same as a stock UK model DX7. So it won't be a disaster. Under continental regs, it will be a disaster, 10mW is hopeless.

As for Australia or NZ... our regs allow 4W, so a US model is legal. We could add output amps... I have run a DX7 at 1W (had to stand back about 20m from the model to avoid saturating it close up!)
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Old Oct 28, 2007, 03:34 AM
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Quote:
Originally Posted by Andrew McGregor
100mW is still the same as a stock UK model DX7. So it won't be a disaster. Under continental regs, it will be a disaster, 10mW is hopeless.
...
The range with a EU DX7 (100mW peak output power) and an AR6100 is only approx. 300m. With the model on the ground it is only approx. 150m.

The EU legal DX7 is marketed by Graupner as a system for Parkflyer, Indoor and Micro-Helicopters.

Jürgen
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Old Oct 28, 2007, 05:38 AM
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Thank you for the replys,

So we are saying that UK law will allow a 2.4Ghz TX with a range of approx 300M. Jurgen, I presume this will be roughly the same irrespective of manufacturer, i.e the Futaba FASST does not increase this?

How does this compare to the range of a normal 35Mhz transmitter? In all honesty I dont know how far I fly the glider away from me but I felt it was more than 300M.

Regards

Chris
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Old Oct 28, 2007, 06:32 AM
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IIRC Jurgen isn't quite right... the UK allows 100mW, same as a US DX7, which gives around 3.5km range, whereas continental Europe is mostly limited to 10mW, which gives around 300m.

FASST is regarded differently by the regulations, and has the same range everywhere, around 2.5km IIRC.

US X9303s have even more output power, and should have a significantly longer range... although past 10km you have to wonder if the radio is the least of your worries.

35MHz is good for about 7km with a top quality RX.

Again, this is all from memory...
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Old Oct 28, 2007, 06:45 AM
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Andrew,

Thank you very much for that explanation. Its clearly a complicated subject and one im struggling to understand so this forum has been great. It seems to me from you reply that a UK version of the DX7 or Futaba with FASST would provide enough range for me flying a 2m glider (3.5km or 2.5km).

My only concern because of limited knowledge is from the UK JR website which seems to indicate that 10mW/Mhz limit also applies in the UK to Spektrum technology so does this mean 300m range? Sorry to keep bashing away at this, I dont want to stick with 35Mhz unless necessary.

Quote:
but because the Spektrum DSM system uses Direct Sequence Spread Spectrum a limitation of a Power Spectral Density not exceeding 10mW/MHz also applies.
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Old Oct 28, 2007, 07:09 AM
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Quote:
Originally Posted by Andrew McGregor
IIRC Jurgen isn't quite right... the UK allows 100mW, same as a US DX7, which gives around 3.5km range, whereas continental Europe is mostly limited to 10mW, which gives around 300m.
The US DX7 is illegal in Europe - that includes Great Britain as well - as it has a peak output power of close to 1000mW. With a duty cycle of 1:10, this is approx. 100mW average. In contrary to the US FCC, Europe limits the peak power output to 100mW.

http://www.spektrumrc.com/Articles/A...ArticleID=1716

Jürgen
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Old Oct 28, 2007, 07:15 AM
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I thought the DX7 had an exemption in the UK? However, that's not what the Spektrum site says...

Well, obviously I didn't recall correctly...

Very glad my countries regulations exceed the US limits by a lot. Means I can get away with importing 2.4GHz stuff from anywhere and not worry about it. Our limits are pretty much the highest in the world... 4W EIRP with a 1 second averaging time is a LOT of power at 2.4GHz.
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Old Oct 28, 2007, 07:16 AM
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Quote:
Originally Posted by Andrew McGregor
I thought the DX7 had an exemption in the UK? However, that's not what the Spektrum site says...

Well, obviously I didn't recall correctly...

Very glad my countries regulations exceed the US limits by a lot. Means I can get away with importing 2.4GHz stuff from anywhere and not worry about it. Our limits are pretty much the highest in the world... 4W EIRP with a 1 second averaging time is a LOT of power at 2.4GHz.
Population density is much higher in Europe than in New Zealand.

Jürgen
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Old Oct 28, 2007, 07:30 AM
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Thanks guys, so Jurgen is the Futaba system higher powered than the spectrum? Or are we basically saying in Europe/UK 2.4 is only good for 300m which would not make it ideal for gliders?

Thanks again both of you for the debate its much appreciated.

Regards

Chris
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Old Oct 28, 2007, 09:39 AM
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Quote:
Originally Posted by cmyers_uk
Thanks guys, so Jurgen is the Futaba system higher powered than the spectrum? Or are we basically saying in Europe/UK 2.4 is only good for 300m which would not make it ideal for gliders?

Thanks again both of you for the debate its much appreciated.

Regards

Chris
The output power is the same, yet the range of the Futaba system at 100mW is much better than Spektrum.

Jürgen
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Old Oct 28, 2007, 01:37 PM
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Please note that Jürgen is stating the distance with the AR6100 receiver. Other tests done with the AR7000 (full range) receiver shows a range of around 1000 meters. Still only half of the range compared to the US version, but not as bad as with the parkflyer receiver. Trusting that equipment in a glider is another matter, and as I understand it also difficult to fit

Also notice that Graupner (like Jürgen says) is promoting the DX7 as a parkflyer radio, but other European distributors, like Horizon UK, is promoting it as a full-range system. That's confusing to say the least...

/Leif
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