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Nov 13, 2019, 09:42 PM
Registered User
Thread OP
Question

Taranis swamping??


Several questions for you guy's,
Why does my Taranis swamp my L9R rx and cause it to 'Failsafe' repeatedly while attempting to launch my plane and is there a fix??
Why if I out fly the range of the Taranis/L9R does it not reconnect unless I turn the TX off and on again?
Using my Eachine LCD5802D screen with a Fatshark CP and 16T Helical I'm getting the best range using a cheap Rubber Ducky (Omni) ??
I've tried a quality Pergoda , and a bunch of quality Spiro's but surprisingly the Omni does the best by several Kms?
Oh and lastly- the Taranis causes a pulsating disturbance on both the LCD580 screen AND my Headplay's ???
Thanks for looking
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Nov 18, 2019, 08:26 AM
'Extreme Fabricator'
The L9R is well known for swamping. It achieves it's amazing 2.4gHz range by utilising active antenna's, where there is an individual RF amplifier inside each paddle, phantom powered and able to increase the tuner's front end sensitivity by a magnitude. To assist with signal quality the number of channels is kept low at 9, allowing for a more discriminating packet size. The antenna gain does have the ability to peg the tuner input envelope, so it's best to launch with the radio antenna pointing away as much as possible, and also keep it as far from the plane as possible.
It should re acquire immediately after losing range, actually I find them one of the fastest at re connecting. It may be worth re binding it, I've had flaky binds with other FrSky X series receivers that cleared up that way. Also, ensure there is good separation distance when you bind, as an overloaded signal can cause issues at that critical point of connection.
Regarding FPV range, have you checked all the usual culprits, like polarisation polarity, sma polarity and antenna integrity (with a multimeter)
I developed a technique to tune my own home made 5.8 antenna's which have since given me a huge increase in range, with some other interesting performance results from other antenna's, like CW helicals, and immersion patches etc, and many are not as good as expected. One thing I see on your groundstation is a 90 degree sma elbow, they rob around 2dB (watch Painless 360's lab test of SMA adaptors... you will toss all the 90's in the bin..lol) 45 degree is nowhere near as bad, around half a dB.
One thing I found, testing over and over with many prototypes, is helical's start losing signal level past five turns. The gain still increases, but with more loss before the signal gets out of the connector. I can measure signal amplitude in a 1-100 scale on a spectrum analyser, and I have tuned a 4 turn helical to outperform 12 turn helicals at under 1.2:1 SWR, and the 4 turn has a usable beam width of over a hundred degrees, the 12 turn is about 30 degrees but with about 20% less signal level out. The 4 turn get's me 10km/600mW and the diversity receiver will not touch the 12 turn antenna pointed dead at the plane. I have given up on high gain helicals as a result, and I even get the same result with the Circular Wireless $$$ ones.
One other thing is, yourcheap rubber duckie may be a freak. I've had a couple over the years that have fluked perfect VSWR and impedance, one I fitted to a plane that easily does 1.5km on 25mW, but only ever with that antenna.

The pulsating effect is usually from poor screening of the display devices. The Taranis isn't outputting much power, generally under 20dBm, so for anything to be affected, it must be adversely sensitive, unless you mean right against it, then EMI will still saturate things even with just 20dBm.
Last edited by alicecooper; Nov 18, 2019 at 08:32 AM.
Nov 19, 2019, 04:32 AM
Registered User
Thread OP
Thanks very much for your extensive reply there Alicecooper, very much appreciated
I manage with the "Swamping" it's just a PITA at times especially since I launch the Z84 with my left hand in order to have my right hand on the controls.
Its when I bring the TX up to my chin to open the throttle that the fun can begin!!
I'll try the RE-BIND idea too thanks.
As for the FPV transmission I'll get my multimeter out and check what you suggest and order some 45deg connectors as you suggest.
The same Tommy D 16t helical always performed very well back in Scotland but that was on my old set up with an FR632 rx WITHOUT a 90deg adaptor !
I could fly out beyond 10kms and not adjust it's aim at all, in fact I also had a 7turn helical on the Fr632 and it never took over from the 16 even at closer range?
I don't know what RX's the Eachine screen contains but maybe they're just not as good as the components used in the Fr632?
What are the best 5.8 RX's in your opinion?
Eachine say their screen isn't affected by 2.4 transmission so it's a bit annoying that it IS while I'm having to stand right by it to see where I'm going
However it nowhere near as bad as the interferance given to the Headplays . I can't use them at all unless I grow 10' long arms
Anyway -again thanks for your wisdom and I'll see what improvements I get
Nov 19, 2019, 05:45 AM
'Extreme Fabricator'
Cheers, I hope it sheds some light on your problems.
I have the same L9R in my Nanotalon, and have to do a shotput ballet launch, with the radio out one way and the plane the other.. I usually use my leg to bump the throttle up, but it is a pain.
With your Eachine screen, one thing you could try is to remove the back cover and line the inside of the rear cover itself with adhesive copper tape, overlap it slightly and solder a short wire to it and connect that to ground on the PCB (Battery negative or input ground)Just be sure it doesn't contact anything when reassembling (even tape over it with packing tape) and it will block most interference sources. Another thing that can help is to attach some clip on ferrite filters to your cables going in just keeping them as close to the unit as possible.
My Taranis was getting severe interference from the UHF module in the JR bay, so I did the copper foil trick to the module and it completely blocked the interference (digital noise in the speaker) and it cost practically nothing to do.
I also saw a trick I'm yet to try using a rubber band to pull the throttle up, except that it usually goes to 100%, but the friend who does it here just hooks it up over a switch, then holds the throttle down with a finger and when launching lets it go... it maybe a bit risky, but he swears by it, he just unhooks the rubber band once the plane's settled. It may be beneficial to program the esc for soft start too.
As far as receivers go, the 632 is very good, the only reason I stopped using mine on my groundstation was because of the power switch, being up a 3.6m mast means partial disassembly to switch it on, then I have to leave it on all day, or pull it down again to restart it.
I recently found an Immersion RC 5.8 duo v4.1 at a giveaway price which has proven to be even better than the 632 for a couple of reasons. One, it has an option to make an audible click when it switches antenna's, secondly it has a deeper diversity sensitivity, I found the FR632 stopped switching receivers at the point where there was about half of the image in snow, or moderately low signal level, but otherwise still flyable, where the Immersion keeps hunting between antenna's until there is nothing visible left in the video signal, usually where you need the best antenna the most, so I can now fly further, despite the sensitivity between the two being on a par, plus the Duo powers up immediately when the battery is connected. I also have a few other groundstation receivers, including an R-600 which is a single (non diversity) ultra sensitive receiver, but I have had some stability issues with it, I also have the Boscam (Eachine) RC832, and RC305's but they are ancient single receivers. I think the 832 is slightly off frequency too, as it's range is more limited than it should be, except on the lowest channels.
If you're in the market it could be worth checking with NextFPV to see if they still have stock of the Duo, it was on clearance sale for a giveaway price (~au$60-ish / ~us$40) and they sometimes get more remnant stock in even after clearing, so also worth sending them an email request to be notified if it's gone.
Nov 20, 2019, 07:40 PM
Registered User
Thread OP
[QUOTE=alicecooper;43193827]The L9R is well known for swamping. It achieves it's amazing 2.4gHz range by utilising active antenna's, where there is an individual RF amplifier inside each paddle, phantom powered and able to increase the tuner's front end sensitivity by a magnitude. To assist with signal quality the number of channels is kept low at 9, allowing for a more discriminating packet size. The antenna gain does have the ability to peg the tuner input envelope, so it's best to launch with the radio antenna pointing away as much as possible, and also keep it as far from the plane as possible.
It should re acquire immediately after losing range, actually I find them one of the fastest at re connecting. It may be worth re binding it, I've had flaky binds with other FrSky X series receivers that cleared up that way. Also, ensure there is good separation distance when you bind, as an overloaded signal can cause issues at that critical point of connection.
Regarding FPV range, have you checked all the usual culprits, like polarisation polarity, sma polarity and antenna integrity (with a multimeter)


Hello Alicecooper, I've had the old multimeter out as you suggested and am totally confused
I tested between the outside of the antenna SMA fittings that protrude out the top of my LCD screen , and the center pins and my continuity meter beeps?
I tested the FR632 and the Headplays the same way and it's not sounding (open circuit) which is what I expected of the Eachine screen?
Now the Eachine is working well enough so I'm assuming there must be some internal component that gives this result?
Can I ask your opinion -or anyone elses of course- please?


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