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Ron Wylie

Carbon Friendly Spektrum Advice

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Ron Wylie

Just installed an 8 ch Spektrum RX, DSMX, with Sat, in a Blaze XL moulded glider and with the wings attached I'm getting very short range. Is there anything, apart from mounting the Sat on the outside, or buying a Carbon Friendly RX, that will cure the problem, please?  Thanks

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oipigface

This is a perennial cry on this forum. When I first heard it, I was astounded that the sellers of this gear could get away with describing their system as ‘carbon friendly’. I can’t explain the physics of it to you, and I don’t know what a ‘Sat’ is, but it is well-known that a number of materials will block radio signals to a greater or less degree. Glass fibre doesn’t, kevlar doesn’t, but carbon fibre most certainly does. In order to enable receiver and transmitter to communicate, it is necessary that there be no carbon fibre in the path of signals between them. Practically, this means that the receiver’s aerials must be outside a carbon fibre fuselage. This is the reason why there are two of them, which can be deployed on either side of the fus., with the ends well away from it. If there is carbon in the wing as well, it still may interfere with the signal in certain orientations (e.g. when a high wing plane is climbing away from the pilot.) When you do a range check make sure that you test the model in as many different orientations as possible.

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SilentPilot

I use Spektrum in Carbon gliders without any issues. 
 

A “sat” is a Remote Receiver (Satellite) that can be positioned well away from the main receiver. 

The only difference with Spektrum Carbon friendly receivers is the length of the antenna.  They are longer so you can route the active portion outside the airframe. 

I’m unfamiliar with the Blaze XL but if it has a carbon structure then you need to run the antennas outside it. 

On my all Carbon gliders I use receivers that utilise multiple remotes and position them around the wing at the root. Two above and two below. I no longer concern myself with 90° orientation because my DX9 & DX18 have diversity antennas on the Tx side so it’s not an issue really. 
 

Tony 

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rwhitt

If your model has a glass or kevlar nose it should work with aerials in there. If it's all carbon then get the a Spektrum ar6270t or the ar9320t the latter has a vario built in and the option of a carbon sat too. I had a Starlite with a full carbon and Kevlar fuse so used the 9 channel carbon rx with 2 aerials outside just in front of the wing and a carbon sat underneath. It worked fine.

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f3fman
52 minutes ago, SilentPilot said:

I use Spektrum in Carbon gliders without any issues. 
.....

. I no longer concern myself with 90° orientation because my DX9 & DX18 have diversity antennas on the Tx side so it’s not an issue really. 
 

 

The TX diversity antennas are doing their best to maximise the signal coming out of the TX in a good direction,  you can still maximise the chance of a good  signal being received by keeping the rx antennas at 90 degrees  🙂

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SilentPilot

I know what you mean, but if it is impractical to layout the antennas this way then I'm happy to have the polarisation provided by the Tx. 

Most of my external antennas are routed outside and allowed to blow back in the airstream. 

I did try taping to wings and fuselages but reception suffered. It is best to keep a gap. 

:)

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Ron Wylie

Thanks for all the replies

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satinet

The wing itself shouldn't make that much difference to range check unless you only check it with the wing between the line of sight from the tx to the rx. 

Where is the rx in the model? 

I think spektrum is the only rf system where I've heard about people using satellites receivers in small models (e.g sport and f3x under 4m as opposed to 7m scalie).  No one really understands what carbon rxs are supposed to do. 

Move the aerials as close to the edge of the fuselage as possible or outside. Aerial orientation is good but if you block the line of sight from tx to rx it will work poorly. Taping the aerial to the fuselage produces poor results if it's carbon. 

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SilentPilot
58 minutes ago, satinet said:

The wing itself shouldn't make that much difference to range check unless you only check it with the wing between the line of sight from the tx to the rx. 

I deliberately check the orientation where the wing is between the antennas.
Isn't the whole point of range testing to check for worst case scenarios?

 

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Gary B

To get a more quantitative idea of the receiver and aerial installation you can use a Spektrum Flight Log

This little box records the number of antenna fades, frame losses and holds, I believe the instructions for it give the acceptable values for a one minute range test.

Spektrum advise a short flight, kept close in, after range test to confirm all is well. The flight log stays with the model and acts as a voltmeter in its default mode.

If you have a crash and the electrics are still working it can give clues to the cause (or eliminate a radio problem).  

It is worth reading the PDF instructions for the AR 9300 as this gives good generic advice for carbon model installations.  

I competed in F3J/F5J using AR9300, JR RD921 (in Kevlar fuselage) and a JR DSX12 for quite a few years with no problems. All were used with one satellite (two could be used).

The aerials were either inside or outside (sometimes a mixture of both where the nose was 'carbon friendly' as in the Tragi 801 and NAN Xplorer).

I've moved to Jeti Duplex now, some of the receivers come in a long antenna version to make external 'whisker' type installations possible.

    Cheers

       Gary

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satinet
2 hours ago, SilentPilot said:

I deliberately check the orientation where the wing is between the antennas.
Isn't the whole point of range testing to check for worst case scenarios?

 

Yes and that was my point.  Unless the rx is right under the wing, and the wing is one peice, it wouldn't make much difference in most orientations.

Usually the worst situation with a carbon glider, even with a glass nose, on a level plane with the fuselage from behind as the aerial are close to being blanked even with 90 degree orientation. It's a problem more often encountered when far away and low in f3j etc. But every model has weak zones due to battery and nose weight etc. The fuselages have become very cramped.

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Big Si

I have been using the New Spektrum rx,s with no aerials and they have been fine

have them in a 3.1m Cobra and most of my DLG,s and also a Min Vector and a Blade XL

in the Blade XL the rx is even mounted on a carbon sandwich board and the range is fine all ways round

in the DLG,s I am using the Spektrum AR410 around £25 and in the bigger gliders with more than 4 servos I am using the Spektrum AR620 £35 ish

Might be worth a look as supper simple to use as no bind plug or aerials to put anywhere just a piece of double sided tape and press and hold a button to bind and that's it

find they are great and if you use a tx with telemetry it has battery so you can keep an eye on your receiver pack while you fly 🙂   

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f3fman

Sounds good.  It looks like the telemetry is only at short range , "fly-by telemetry".

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SilentPilot

I use an uncased AR410 in my Vibe2.
Yes the telemetry is only short range but reportedly slightly better (longer) than the AR636.

I do have an AR620 in my Redshift but as yet, although it has passed range tests with flying colours, it hasn’t had a thorough flight test yet.


One thing to bear in mind when using Spektrum receivers:
If the receiver comes with a remote (satellite) then it must be used with one. This is particularly applicable to 7ch or higher receivers so not so much an issue with DLG but definitely something to bear in mind for F5J.

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Big Si

Well had a good afternoon up Church Stretton on Saturday with the Blade XL using the  Spektrum AR620 and had no problem with range what so ever

had a few good flights setting the glider up and flying as high and as far as I could each flight to test the rang and it was fine with no issues other than a tad nose heavy (now sorted )

like I said its even mounted on a piece of carbon board along with the 2 tail servos and the switch

4 others were up there and are all members on here so can vouch for the range  and the lovely noise it made when doing a roll |:-)

well worth a go with one that's for sure as I now have 5 in models all with a lot of carbon in them and they have been better than any with aerial's  on 

so I am very pleased with them and the price as I am still the good old DSM2  

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SilentPilot

Get tha sen on DSMX :D

 

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