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Topic-icon Problem: Low range after WK-DEVO-S Upgrade of 7e

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11 Jan 2017 09:46 #57807 by eirikso
I recently installed the WK-DEVO-S-MOD Upgrade on my Devo 7e. I installed the module like described here:
www.hacksmods.com/2014/10/wk-devo-s-mod-module-for-devo7e

After the mod my radio works fine. It binds perfectly to my quad and controls it like it should. But my range is worse than with the original module.

When I measure the output I get around 0.3 mW. It should have been 100 or 150. I am running the latest stable build of Deviation and have edited hardware.ini with has_pa-cyrf6936 = 1.

When I removed the old module I had trouble with some of the pads, but managed to solder directly to the small dot leading through the PCB.

And because the radio finds the module and everything works like it should with binding and controlling all the channels my idea is that the soldering is OK. If one of the connections is bad I would guess that the radio would not work at all?

So my question is:
1. Can bad soldering of one of the connections cause OK binding etc but bad range? If so, which of the connections could lead to poor range if the connection is bad?

2. If the fact that the module binds and works means that the connections is OK. What can I do to improve the range?

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11 Jan 2017 15:06 #57819 by HappyHarry
what antenna are you using on the tx? how are you measuring the tx power?

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11 Jan 2017 15:16 #57821 by eirikso
Using a standard 2.4 Ghz whip. And measuring the power directly from the TX with the Immersion RC power meter.

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11 Jan 2017 15:17 #57822 by eirikso
...and watching my Eachine QX95 drop to the floor due to no signal at 5 m distance...

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11 Jan 2017 18:04 #57833 by HappyHarry
have you made sure the u.fl connector isn't damaged and is seated properly? have you checked the voltage that the module is receiving when it's transmitting? what all have you done to try and troubleshoot and what were the results? as there's obviously an issue somewhere, did you ever power the module without the antenna/rf meter connected?

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11 Jan 2017 19:15 #57834 by Cereal_Killer
What's the measured voltage you're supplying the new Devo module (please actually measure)?

Taranis X9E | DEVO 10 | Devo U7E

What I do in real life: rivergoequestrian.com/

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13 Jan 2017 14:39 #57892 by eirikso
I am sorry for the delay. Have been traveling so I haven't been in reach of the radio before now.

Thank you very much for all the information. This really helps when I now keep on debugging.

I have measured actual voltage and it is 5.5 Volts. I have not powered it without an antenna connected.

I went over and measured connection on all the cables and checked again for possible problems.

I also disconnected the antenna and checked the connectors. And I think I found the problem. When I measure connection in the center of the U.fl connector up to the antenna it seems like there is a bad connection.

Unfortunately I don't have a spare right now, but I testet by connecting an antenna that has an U.fl connector. I can not measure the direct power with that solution, but I can connect an antenna to my Immersion RC power meter and check if the signal reach the power meter.

And I now measure a huge difference.

So my conclusion so far is: there was a problem with the cable between the Ufl-connector and the SMA-connector. Meaning that the module probably have been powered up several times without a proper connection to the antenna. This could have damaged the module. But my tests so far with the antenna that I have here now, directly connected to the U.fl seems promising.

I'll do some more tests and check back here when I get hold of a new Ufl->SMA adapter so that I can measure the actual output power.

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13 Jan 2017 15:31 #57894 by HappyHarry
glad to hear you have found the issue bud, jfip powering the module with no antenna doesn't always damage the pa but it is a high possibility, though with the initial results you have it sounds like you've been one of the lucky ones, perhaps the connection, while bad, was still enough of an outlet to prevent damage.

i'd be glad if you post back once your new u.fl>sma arrives and you test the modules output again, and if I could ask a favour for the community in that could you test each rf chip at tx power settings of lets say 30mw,100mw and 150mw and post the results from the inversion meter it would be much appreciated

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13 Jan 2017 23:37 #57912 by eirikso
As soon as I get the connector I'll measure and publish the results.

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