ELRS link quality issues | ExpressLRS Community | Page 1

left ginkgo Apr 14, 2024, 4:12 PM

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Hi! I have a 5 inch quad running a Foxeer 2.4GHz rx connected to a TMOTOR F4 HD flight controller.

I really can't make it work properly. I tested all the available recievers I had on hand (Darwin FPV Cement 2.4GHz, Namimno Dual Antenna, Radiomaster RP1. All of them behave the same. My Jumper T20 ramps up quickly to 1W, and even 200 meters out, i get intermittent Link Quality issues, and at about 300 meters, it failsafes and quickly recovers. This is in an open field by the way.

I tested all of the abovementioned recievers on my 3" quad and they all work really well.

On the drone that manifests these issues, I tried different antenna mounts. On the rear (but that's too close to the O3 antenna, i thought), then I moved it to the front, right outside the camera cage, and then I mounted it on the arm. No change in behaviour.

Also tried different UARTs.

How could I diagnose this issue? Can this be flight controller related?
What puzzles me is that the issues only started manifesting after i transplanted the components from a Lumenier QAV-R 2 frame to a GEPRC Mark 5 frame. Before that, I had no issues.

Thanks in advance.

golden saffron Apr 14, 2024, 4:14 PM

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post a photo of the receiver in question and post a screenshot of the expressLRS webui of the receiver
Banner, Options Tab and also the
hardware.html page (at least just the section AFTER the banner, not the long pin definitions)

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Also post a result of the !benchtest from this receiver and one from the better ones

spice starBOT Apr 14, 2024, 4:15 PM

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Follow this tutorial to bench test your hardware before you fly:
https://www.expresslrs.org/quick-start/pre-1stflight/#bench-test

left ginkgo Apr 14, 2024, 4:15 PM

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What did you mean about the rx photo. solder pads or just the reciever model in general?

golden saffron Apr 14, 2024, 4:15 PM

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"post a photo of the receiver"

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if I wanted pads, I'd asked for the pads

left ginkgo Apr 14, 2024, 4:16 PM

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golden saffron Apr 14, 2024, 4:16 PM

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right.. I can google that too

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shouldn't have asked..

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I want a photo of your ACTUAL receiver

left ginkgo Apr 14, 2024, 4:17 PM

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yep, understood now

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be right back

golden saffron Apr 14, 2024, 4:20 PM

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reasons I asked for what I have asked

I wanna confirm you flashed the right target into your receiver..
I wanna check if the hardware definitions been altered one way or another

left ginkgo Apr 14, 2024, 4:43 PM

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Screenshot_2024-04-14-19-40-35-953_com.android.captiveportallogin.jpg

Screenshot_2024-04-14-19-42-26-621_com.android.chrome.jpg

golden saffron Apr 14, 2024, 4:51 PM

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waiting for Bench Test results

left ginkgo Apr 14, 2024, 4:51 PM

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yep, doing this right now

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golden saffron Apr 14, 2024, 4:56 PM

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lift both up from the surface

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e.g. prop up the drone on a mug, box, lipo pack then hold the radio how you hold it while flying the drone

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also, the receiver null is pointing straight to the tx.. so you're not really giving it much chance

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you're settinig it up to fail from the get-go

left ginkgo Apr 14, 2024, 5:00 PM

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golden saffron Apr 14, 2024, 5:01 PM

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so that's how you fly your drone? with the controller on the ground?

left ginkgo Apr 14, 2024, 5:02 PM

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well, the drone is clearly higher than the controller, so I assumed that's what you meant. Lifted the antenna on the RC a bit

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but doing what you said rn

golden saffron Apr 14, 2024, 5:03 PM

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hold the radio how you hold it while flying the drone

left ginkgo Apr 14, 2024, 5:05 PM

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golden saffron Apr 14, 2024, 5:06 PM

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left ginkgo

what's the power level on the t20?

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and what firmware version is on it?

left ginkgo Apr 14, 2024, 5:08 PM

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3.3.2

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golden saffron Apr 14, 2024, 5:10 PM

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left ginkgo

is that 25mW just for the bench test?

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at 25mW, the bench test should be better than the 10mW baseline

left ginkgo Apr 14, 2024, 5:11 PM

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golden saffron is that 25mW just for the bench test?

yeah, just for the bench test

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normally i keep it on 1W Dynamic just because i fly fixed wing too

golden saffron Apr 14, 2024, 5:12 PM

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reflash the receiver to 3.3.2 as well.. since it was on 3.2.1, right?

left ginkgo Apr 14, 2024, 5:12 PM

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yep, 3.2.1

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so, reflash and then I'll do the bench test again

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?

golden saffron Apr 14, 2024, 5:12 PM

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yes

left ginkgo Apr 14, 2024, 5:16 PM

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golden saffron Apr 14, 2024, 5:16 PM

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does the t20 still rocking the factory firmware or you've already flashed it yourself?

left ginkgo Apr 14, 2024, 5:20 PM

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flashed it myself

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if you mean the ELRS TX module

golden saffron Apr 14, 2024, 5:21 PM

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left ginkgo if you mean the ELRS TX module

yes..

left ginkgo Apr 14, 2024, 5:21 PM

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left ginkgo

is this value that bad tho?

golden saffron Apr 14, 2024, 5:21 PM

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it could be better

left ginkgo Apr 14, 2024, 5:21 PM

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yeah, i'm trying this with my 3"

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so curious

golden saffron Apr 14, 2024, 5:21 PM

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see this value is more of a 10mW acceptable value.. for 25mW, it's kinda "low-ish"

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and you also have a receiver with an LNA.. so compared to one without an LNA, it should be a LOT better.. since the incoming signals are filtered, then boosted

left ginkgo Apr 14, 2024, 5:24 PM

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3 inch looks worse. Yet I have no issues flying it 700 meters away on 50mW

golden saffron Apr 14, 2024, 5:25 PM

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left ginkgo

what receiver is on it?

left ginkgo Apr 14, 2024, 5:25 PM

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just a second

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it uses the BetaFPV Nano 2.4GHz target

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but it's called "DarwinFPV cement"

golden saffron Apr 14, 2024, 5:25 PM

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also has an LNA..

left ginkgo Apr 14, 2024, 5:25 PM

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https://darwinfpv.com/products/darwinfpv-cement-ultra-durable-elrs-2-4g-receiver

DarwinFPV

DarwinFPV "Cement" Ultra Durable ELRS 2.4G Receiver

The original design intention of the "cement" ultra-durable series of products:How to make fpv drone break through the environmental limit again? To enhance the fun of flying for players, experience different flying perspectives, shoot different materials, and not be afraid of dust, rain, snow and any harsh environment

golden saffron Apr 14, 2024, 5:26 PM

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but it was from darwin.. so not the same experience as the actual betafpv nano..

left ginkgo Apr 14, 2024, 5:26 PM

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now i'm trying the plane too 😄

golden saffron Apr 14, 2024, 5:27 PM

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do your flight/s, record DVR.. LQ and RSSI dBm on osd.. .
and also twist the antenna so it isn't perfectly flat.. heck full vertical would be better then horizontal, more so you have the receiver antenna on the arm..

left ginkgo Apr 14, 2024, 5:28 PM

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left ginkgo Apr 14, 2024, 5:28 PM

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golden saffron do your flight/s, record DVR.. LQ and RSSI dBm on osd.. . and also twist the ant...

sadly I can't record DVR

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with the OSD on

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I'm using O3

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with the Goggles V2 :/

golden saffron Apr 14, 2024, 5:29 PM

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huh.. so you still can't reprocess dvr and overlay the osd after the fact on O3?

left ginkgo Apr 14, 2024, 5:30 PM

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nope, really miss that feature. Used it a lot on my old vistas running wtfos

golden saffron Apr 14, 2024, 5:30 PM

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fry

left ginkgo Apr 14, 2024, 5:30 PM

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they have a really shitty .srt file that has some framecount and position data(that's always null)

golden saffron Apr 14, 2024, 5:31 PM

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https://www.youtube.com/watch?v=9wPwoy2PV0Y&pp=ygUObzMgb3NkIG92ZXJsYXk%3D

YouTube

One Man Unmanned

DJI Goggles V1 & V2 Can Now Record BetaFlight OSD in DVR..Here's How!

The DJI Goggles V1 and V2 have been great performing units for some time now, but over the years, pilots have continually asked for Betaflight OSD support. The team at FPV WTF has finally answered our prayers and engineered a way to make this feat happen. Today we’ll be taking quick dive, demonstrating how to see Betaflight OSD in you V1 and V...

▶ Play video

left ginkgo Apr 14, 2024, 5:31 PM

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yeah, this is not valid for O3 mode

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to use an O3 air unit the goggles boot a different firmware

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and wtfos doesn't run on that

golden saffron Apr 14, 2024, 5:32 PM

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ugh.. good thing I'm too poor for dji

left ginkgo Apr 14, 2024, 5:32 PM

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honestly wish you'd prove me wrong since I really want some OSD in my recordings 😦

left ginkgo Apr 14, 2024, 5:33 PM

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golden saffron ugh.. good thing I'm too poor for dji

every o3 is bought in 4 installments 😄

golden saffron Apr 14, 2024, 5:33 PM

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at what LQ level do you have your warnings set? and what about your RSSI dBm?

left ginkgo Apr 14, 2024, 5:34 PM

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honestly i deactivated the RSSI in my OSD since the only things I care about are LQ and TXPwr

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but it gets so bad it failsafes after 300m

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so, for about 150m it works fine on 25-50mW

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it keeps the LQ at a steady 99-100

golden saffron Apr 14, 2024, 5:35 PM

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rssi dBm

left ginkgo Apr 14, 2024, 5:35 PM

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didn't track taht

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didn't track that

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i can do a test and place it in my yard, 200m away

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does that work?

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i'll just place it on a tree branch with the antenna pointed towards me

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just wondering if i should keep it on 25mW like the bench test

golden saffron Apr 14, 2024, 5:37 PM

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bench test should be enough to get a picture of your baselines..

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which can be interpolated with your "away" performance

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it's also comparable to known values..

left ginkgo Apr 14, 2024, 5:39 PM

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golden saffron at what LQ level do you have your warnings set? and what about your RSSI dBm?

whatever the default is

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i think 80

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saw it go as low as 55 , 300-ish meters away

golden saffron Apr 14, 2024, 5:41 PM

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I'd set LQ warning to 60 to 70

then rssi dBm to say -95dBm

left ginkgo Apr 14, 2024, 5:47 PM

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Alright! So, that's pretty much all I can do for now, no?

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there isn't any obvious issue

golden saffron Apr 14, 2024, 5:49 PM

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nothing obvious.. your results are kinda low for the equipment you have at the power level that your tx is on..

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should still get you far, more than 300m

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do you have your arming switch set to aux 1?

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power will boost to max when LQ is lower than 50%, there's sudden LQ drop, or telemetry was lost when setup is armed

left ginkgo Apr 14, 2024, 5:52 PM

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golden saffron do you have your arming switch set to aux 1?

yep

austere falcon Apr 14, 2024, 6:36 PM

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Is this component in short circuit to the other component?

golden saffron Apr 14, 2024, 6:37 PM

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austere falcon Is this component in short circuit to the other component?

no.. from this angle at least..

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should be able to reflow it

left ginkgo Apr 14, 2024, 6:52 PM

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By the way, I think we can rule out the receiver itself since I tried the other three ones I have, with similar results

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Replaced antennas twice, too

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It's driving me insane because it's only happening on the 5 inch one

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Put this same receiver on the 3 inch, and I can fly 1.5km on 50mW

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Did you guys ever encounter issues with the flight controller itself that would, in turn, affect the ELRS link like this?

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Because the same flight controller manifested some issues with a GPS module in the past, but they went away once I swapped the GPS module.

golden saffron Apr 14, 2024, 6:55 PM

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which fc is it?

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and it's also RF related.. so the FC won't really play much role on it..

left ginkgo Apr 14, 2024, 6:57 PM

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golden saffron and it's also RF related.. so the FC won't really play much role on it..

I was thinking more about the UART connection.

left ginkgo Apr 14, 2024, 6:57 PM

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golden saffron which fc is it?

TMOTOR F4 HD

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This is how the other issue manifested

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golden saffron Apr 14, 2024, 6:57 PM

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try this: remove the receiver from the FC, bench test.. see if that result improves..

this way you can rule out the FC

left ginkgo Apr 14, 2024, 6:58 PM

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golden saffron try this: remove the receiver from the FC, bench test.. see if that result impro...

So, just power it on 5V and that's it?

golden saffron Apr 14, 2024, 6:59 PM

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left ginkgo So, just power it on 5V and that's it?

heck, might want to even fully disconnect it from the fc.. isolate it..

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so you can really rule out the FC

left ginkgo Apr 14, 2024, 7:00 PM

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My brain ain't braining

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What are we trying to measure here?

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Or are you saying to just power it from a separate 5V source

golden saffron Apr 14, 2024, 7:01 PM

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you're suspecting the Fc is affecting the receiver's reception

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so I'm suggesting remove the FC from the equation altogether

left ginkgo Apr 14, 2024, 7:03 PM

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So, this same receiver was paired with two other flight controllers on different drones, and it worked perfectly fine

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So I guess I have my answer...

left ginkgo Apr 15, 2024, 6:08 PM

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So, it isn't the FC

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I swapped the FC too and I swapped the reciever to a new Namimno 2.4GHz diversity

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Small improvement, but i'm still getting bad results.

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is this antenna placement bad?

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potent spear Apr 23, 2024, 11:10 PM

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left ginkgo Small improvement, but i'm still getting bad results.

Could there be something/some area on the test flight path that has a terrible amount of interference?
I had rxloss and crazy rssidbm fluctuations at 350m when I flew near a windmill. Couple of times now at the same point my signal chucks it.
Could you test fly out in another direction or location?

steady olive Apr 24, 2024, 11:10 AM

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He had a T20 with an Antenna, internally not connected to the TX module.

potent spear Apr 24, 2024, 12:40 PM

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oooft that won’t help range 🙃

left ginkgo Apr 24, 2024, 3:23 PM

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steady olive He had a T20 with an Antenna, internally not connected to the TX module.

it was connected to the module, but the antenna itself was bad

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Jumper is sending me a free replacement

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until then, my buddy gave me his old T20 sma antenna

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works amazing

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7km away and I was still on 25mw

steady olive Apr 24, 2024, 3:27 PM

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A T-antenna from an RX will also do the Job. This is well known for Jumper tpro.

lyric marsh Apr 24, 2024, 6:36 PM

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steady olive A T-antenna from an RX will also do the Job. This is well known for Jumper tpro.

Is this a upgrade for the t pro v2? It comes with a T housing but has a monopole inside.

steady olive Apr 24, 2024, 6:39 PM

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I have changed it in the "old" t-pro, in the housing was also a simple monopole. The gain was huge.

#ELRS link quality issues