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Oo 2.4 which way should the aerial point

Started by THE BLACKBIRD, December 03, 2013, 17:04:32 pm

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THE BLACKBIRD

Having lost 9 planes in the last 2 years on jr / spectrum and before anybody says pilot error all contact with the models was lost, and not only me but other people as well, I think it is 4 jets including mine that have dived in amongst other models nearly all in the same spot
so I switch to futaba  a 14sg with eight channel receiver, on my second flight with a f3a and the futaba on the second but last turn coming into land it did not turn went straight on and in, a few weeks later a large jet again with futaba and all the top gear installed including the top power box  on its second last turn coming into land in exactly the same place as mine did not turn and went straight on and in, totalled it, this last Sunday morning having avoided the area since my mishap I drifted into it and again lost all control again with a f3a it started doing all sort of things luckily I got it back just before it hit
in the model shop yesterday I was talking to a man that has flown in comps all over the world and he asked ( where dose you tx aerial point) I said to the right and up at 45 deg angle, that is where your trouble is he said, your aerial should point straight in front of you and downwards,
I had noticed when watching the jet world champs on you tube recently that the Russian champ had his aerial pointing straight forward and down
my 14sg only points straight forward and up 90 deg and to the left 90 deg that how futaba made it
so who is right 
The man that never made a mistake
Never made anything

Saxon

December 03, 2013, 17:56:12 pm #1 Last Edit: December 03, 2013, 17:57:52 pm by Saxon
I fly straight forward and up at 45' (Dx6i, hacked Frsky Futaba 9c and a Futaba T8FG)

Haven't ever lost one on 2.4 (kiss of death)  :xx :xx :xx

John

tomkfly

Depends on how you hold the transmitter. You should make sure the end never points at the model.

Tom
When you change the way you look at things, the things you look at often change.        www.deesidemac.co.uk
Gravity, thou art a heartless bitch

Arceenut

Antenna radiation is at right angles to the antenna, least radiation off the end of the antenna.  Try to hold the antenna at right angles to the plane.  I have my antenna pointing straight down,
Lead, follow or get out of the way!

itsme

Mine is always to the side, stays that way in the case.

Sent from my GT-I9300 using Tapatalk


FrankS

If you look at all the new radios coming out without a positionable aerial they seem to have it horizontal in the Tx case except for Spektrum who have two aerials at 90 deg to each other on their new high end sets.

Basically the weakest transmission signal will be from the end of the aerial, and the receiver will be at it's weakest when neither aerial is at 90 deg to the transmitter aerial. So if you had your Tx pointing at the plane and the rx aerial at 90 deg to the tx was shielded so only the one in line was "visible" then that would be the poorest reception. Although you may think you've got a bad patch of sky it maybe that when the plane is in that area the positions of the Tx and Rx aerials are at their worst.

I fly with my aerial either at 90 deg horizontal or pointing down, on my telemetry logging I've never seen less that 100% signal quality in flight, but if the plane is on the ground at distance and I point the aerial at it I can see 60 - 80% signal quality.

peterleigh

FrankS  .....I got it down to 20%LQI >10 errors intermittantly with model ground level .1 mile distance line of sight , wet ground ...TX 1m off ground,aerial straight down.

Normal flight 100%LQI  tx aerial down unlimited range .reducing to 70%LQI  tx aerial pointing directly forward range 200m.

BrianL

At the risk of being boring, this all encourages me to carry on using 35 MHz - I haven't lost a plane for years.  (Erm, apart from the two occasions when I forgot to extend the aerial  :embarassed: )

w8racer

I fly Multiplex 2.4 with tx aerial pointing 45 degrees to the right and never had a problem (touching wood).
With Mpx telemetry receivers I have "LQI" which is some measure of signal strength/link integrity received by the model. It would be interesting whether changing the orientation of the tx aerial affects this figure - normally 100%. I suspect it doesn't.
Robert Welford

itsme

Brian- I never lodt a plane to radio on 35 either, I was dragged on to 2.4 but find it faultless, both my Futaba and my Hitec.

Sent from my GT-I9300 using Tapatalk


pchristy

The fact that you've had so many failures with different makes of equipment all in the same location leads me to think you have a local interference problem! As others have said, there is a "dead" spot off the tip of the aerial, but it is very small. A model would normally pass through it without you even noticing.

Bear in mind that 2.4 GHz is not exclusive to model control. It is a shared band. It sounds to me as if you have another user of the band nearby and that you are passing through the beam of his signal. In view of the expense that this must have cost you, I would recommend getting one of these:

http://www.wifigear.co.uk/metageek-wi-spy-24x-spectrum-analyzer-with-rp-sma-connector

The prices seem to have gone up quite a lot since I bought mine a few years back, but its still cheaper than a wrecked model - especially a turbine! One of these plus a laptop will give you a very good idea of what's happening on 2.4 GHz at your field. And if you get a cheap directional aerial (as used for WiFi routers) you can probably get a bearing on any local source of interference.

However, bear in mind what I said about this being a shared band. If there IS interference, it might well be legitimate, and there is nothing you can do about it - except go back to 35 MHz.

35 MHz is (for all practical purposes) exclusively OURS, and is now almost empty!

Best of luck!

--
Pete
"No matter how much you push the envelope, it'll still be stationery."

EssJay

I hope the mods won't mind me linking to a thread in another forum, but it seems that someone had a problem with interference on 2.4GHz, and it turned out to be a high powered WiFi repeater.

http://www.modelflying.co.uk/forums/postings.asp?th=89942&p=1
No trees were harmed by this post, but some electrons have been slightly inconvenienced

pchristy

Further to my above post about the Wi-SPY Spctrum Analyzer, I think the BMFA have one of these, which should be available to member clubs for an on-site survey. If you don't want to splash out on one yourself, give BMFA Head Office a call.

--
Pete
"No matter how much you push the envelope, it'll still be stationery."