TX16/ R88 Low RF - Am I doing something wrong?

[Graham Davies 3]

Found a way!

 

With the Radiomaster R88 receiver fine tuned on D8, I get 74 to 81 dB at 5ft; both receiver antennae parallel to the TX antenna.

 

Same test with a brand new FrSky X8R gets 76 to 84dB.

 

That's a fair chunk less...

 

Graham

[Mike Blandford]

What firmware are you running on the Tx (openTx, erskyTx, edgeTx)?

 

Mike

[Graham Davies 3]

Just updated:

EdgeTX:  V2.9.2

Module:  V1.3.3.33 AETR

 

Graham

[Peter Christy]

Graham, problems like this are very difficult to diagnose at a distance. To do it properly you need some fairly special test equipment that not many people - even dealerships - have.

 

Most repairers would simply replace the RF board, but again, this is not something for the faint-hearted to attempt! Whilst most manufacturers have standardised on tiny "snap-fit" co-ax connectors, even these can be easily damaged (the centre pin is miniscule!). Soldered connections require very good soldering skills due to the tiny dimensions of the co-ax cable used.

 

You really do need to establish if it is a transmitter issue or a receiver one. I've always found the FrSky D8 receivers to be pretty bullet-proof, but the after-market clones do seem to be built down to a price, not up to a specification! There again, who knows who is actually manufacturing the multi-protocol modules inside the Tx?

 

My own experience with FrSky, going back over a decade now, is that they are just as well made as JR or Futaba. I also have a Radiomaster T16-2S, which has also proven reliable. However, it did have range issues when used with an Orange DSM-X receiver. I put this down to the Orange receiver, as the Tx worked fine with Spektrum receivers, although those were DSM-2, not DSM-X.

 

I would suggest that your best choice would be to send the Tx and Rx to Mike Ridley: https://modelradioworkshop.co.uk/servicing/

 

Mike has years of experience with fixing RC gear, and has the test equipment to do a thorough job. I would be willing to check the gear over, but I don't have any spares for Radiomaster - or indeed anything else, except stuff I designed decades ago! Mike Blandford also is very experienced, but I don't think he does servicing (Mike?).

 

Mike Ridley does this for a living and can be relied upon to do a thorough job. I strongly recommend contacting him!

 

--

Pete

 

[Graham Davies 3]

Thanks Peter,

 

Yes, I understand both the complexity in accurately diagnosing a fault, and also in repairing it. Also, the last thing I want to do is to put doubt in the minds of current TX16 users as I am aware that many, many things could be contributing to the issues I see, including the user! 

 

One problem I have is that we build up our confidence in our gear from a number of good experiences. It is only when something goes wrong that we can then start to analyse the clues we have. In some cases, things we see only seem a problem after the event (such as a range check that gets to 25 paces; this all seems very unscientific to me!). I'm now in the opposite position where I need some evidence to restore my confidence. A service from a skilled and qualified engineer would go a long way towards that,

 

Graham

[Graham Davies 3]

Quick update:

 

Managed to get a couple of flights in today before my thumbs froze.

 

Since last time:

Brand new FrSky X8R receiver

Updated EdgeTX software

Updated RF Module firmware

RSSi indictor added to my front page. reads around 85dB when I'm ready to take off...

 

Range checking today got a comfortable 45 paces at better than 35dB. Enough to be confident to commit aviation. Two flights before I froze with no problems, or low RF reports.

 

There's a slow rebuilding of confidence, but today went a long way. I will try the Radiomaster receivers at some point because I still can't believe they have no use at all.

 

Graham

[Outrunner]

12 hours ago, Graham Davies 3 said:

Quick update:

 

Managed to get a couple of flights in today before my thumbs froze.

 

Since last time:

Brand new FrSky X8R receiver

Updated EdgeTX software

Updated RF Module firmware

RSSi indictor added to my front page. reads around 85dB when I'm ready to take off...

 

Range checking today got a comfortable 45 paces at better than 35dB. Enough to be confident to commit aviation. Two flights before I froze with no problems, or low RF reports.

 

There's a slow rebuilding of confidence, but today went a long way. I will try the Radiomaster receivers at some point because I still can't believe they have no use at all.

 

Graham

 

That's good news, hopefully no more problems.

 

I'm interested how you get on with the Radiomaster receivers as I have a 6ch and 8ch. I bought them a couple of years ago with my RM Tx16, the 6ch is in a boat, no issues, the 8ch is used on the bench, never flown yet and I'm not sure why but I think I might have read somewhere probably on RC groups about people having problems with them, probably nonsense.

Edited November 27, 2023 by Outrunner
Typo

[Edgeflyer]

I had exactly these problems with tx16s even with new FRsky receivers. I sold the tx and got a FRsky tandem x20 running Access . I still don't trust it as I get RSSI warnings all the time at close range. I'm now going over to ELRS using a tx module. Much more reliable.

[Graham Davies 3]

1 hour ago, Outrunner said:

'm interested how you get on with the Radiomaster receivers as I have a 6ch and 8ch. I bought them a couple of years ago with my RM Tx16, the 6ch is in a boat, no issues, the 8ch is used on the bench, never flown yet and I'm not sure why but I think I might have read somewhere probably on RC groups about people having problems with them, probably nonsense.

Hi Outrunner,

 

I have a load of R88 receivers and I don't think I've had any SERIOUS issues, I do get lots of RSSI warnings. Mike at HobbyRC recommended against these, which is a shame as they represent great value. Not so great if you lose a model though! I do worry bout range with them, and given recent issues, am not keen to use them. However, I do also accept that if I get a positive result on the R88s, I know that any low output issues were as a result of the firmware, so I may give one a go and see how they compare.

 

Edgeflyer, there's nothing worse than losing faith in your gear, is there? What module did you go for, and what receivers do you use? I am interested to try this as it means I retain all the good stuff from the TX16.

 

Graham

 

[Lipo Man]

Really sorry to hear about these problems - nothing worse than not being able to trust your gear, especially if it’s a model in which you’ve invested a lot of time or money. I have a couple of Radiomaster 6 channel receivers and they’ve been fine working with my TX16s - it really does seem that there is no visible logic to explain how some people get lucky and some have problems. I’ll definitely keep a closer eye on the RM receivers I’m using after reading this. 

[Outrunner]

28 minutes ago, Graham Davies 3 said:

I have a load of R88 receivers and I don't think I've had any SERIOUS issues, I do get lots of RSSI warnings. Mike at HobbyRC recommended against these, which is a shame as they represent great value. Not so great if you lose a model though! I do worry bout range with them, and given recent issues, am not keen to use them. However, I do also accept that if I get a positive result on the R88s, I know that any low output issues were as a result of the firmware, so I may give one a go and see how they compare.

Graham, I only have one R88 and I believe it's the version that was withdrawn from sale as they infringed FrSky copyright. I only paid £9 for it and quite soon after they doubled in price so I don't really care if I only ever use it as a bench receiver. Using the built in Rx battery telemetry port I get incorrect voltage readings, a 4 cell lipo reads out at about 12V so not very helpful.

 

I did have some weird things happen with Hitec receivers that worked perfectly ok with my Hitec Tx but strange with RM Tx16. No crashes  but odd results during range checks so I don't use them with the RM. And yes I did the fine tuning.

 

I have been buying Lemon receivers and so far I've had very positive results and great value for money and the 7 & 10 channel are bristling with telemetry functions and built in 3 axis gyro. So far the range has been fine and I'm very confident in using them , even the single antenna 6ch version has really good range.

[Guest]

52 minutes ago, Graham Davies 3 said:

Hi Outrunner,

 

I have a load of R88 receivers and I don't think I've had any SERIOUS issues, I do get lots of RSSI warnings. Mike at HobbyRC recommended against these, which is a shame as they represent great value. Not so great if you lose a model though! I do worry bout range with them, and given recent issues, am not keen to use them. However, I do also accept that if I get a positive result on the R88s, I know that any low output issues were as a result of the firmware, so I may give one a go and see how they compare.

 

Edgeflyer, there's nothing worse than losing faith in your gear, is there? What module did you go for, and what receivers do you use? I am interested to try this as it means I retain all the good stuff from the TX16.

 

Graham

 

The Radiomaster Ranger elrs module for tx16s should work well but you also need elrs receiver's. Fortunately they are very cheap and the range is several km even with "normal" single wire antennae.

https://www.hobbyrc.co.uk/radiomaster-ranger-micro-24ghz-elrs-module

https://www.hobbyrc.co.uk/radiomaster-er8-8ch-elrs-receiver

 

My Ranger tx module had to be the Lite version for the x20 as its module bay is smaller.

 

With this system you also get full telemetry.

[FlyinFlynn]

4 hours ago, Philip Baker said:

......... and the range is several km even with "normal" single wire antennae.

 

It is questionable what 'extra' range performance one of these elrs radios will actually provide you with when, in Europe, the claimed maximum output power achievable by this radio is restricted from 1watt (30dBm in the US) to 100mW for use in Europe. (20dBm EIRP)... the same as pretty much every other R/C Tx module.

Edited November 27, 2023 by FlyinFlynn

[Peter Christy]

I think you'll find that in the US its only 200mW (23dBm) permitted. That's not to say that people aren't using 1 watt, but back in the bad old days of CB radio, there were people putting out 1KW, when the maximum legally was 4 watts...

 

100mW will give you out-of-sight range in the air, just like it did on 35 MHz. How much more do you need? One of my colleagues used 2.4 GHz for controlling cameras for wildlife videos in Africa, and recorded several KM of GROUND range on 2.4 GHz - which would translate to much more in the air.

 

If you are short of range at 100mW, something, somewhere is very wrong!

 

--

Pete

 

[Outrunner]

5 hours ago, Outrunner said:

Graham, I only have one R88 and I believe it's the version that was withdrawn from sale as they infringed FrSky copyright. I only paid £9 for it and quite soon after they doubled in price so I don't really care if I only ever use it as a bench receiver. Using the built in Rx battery telemetry port I get incorrect voltage readings, a 4 cell lipo reads out at about 12V so not very helpful.

 

This should have read R168, sorry wrong number.

[GrumpyGnome]

I have a few R168 receivers, and use them with my RM TX16 - had zero issues.

[Outrunner]

49 minutes ago, GrumpyGnome said:

I have a few R168 receivers, and use them with my RM TX16 - had zero issues.

 

GG, do you use the voltage telemetry?

[Graham Davies 3]

2 hours ago, Peter Christy said:

I think you'll find that in the US its only 200mW (23dBm) permitted. That's not to say that people aren't using 1 watt, but back in the bad old days of CB radio, there were people putting out 1KW, when the maximum legally was 4 watts...

 

100mW will give you out-of-sight range in the air, just like it did on 35 MHz. How much more do you need? One of my colleagues used 2.4 GHz for controlling cameras for wildlife videos in Africa, and recorded several KM of GROUND range on 2.4 GHz - which would translate to much more in the air.

 

If you are short of range at 100mW, something, somewhere is very wrong!

 

--

Pete

 

 

I think this is the point I'm trying to resolve; am I getting maximum permissible output? I'm not looking to solve a problem no-one else has by swamping the world with unauthorised RF... After all, I imagine most radios comply with the Radio equipment Directive, and most people don't have problems.

 

A few posts back Mike Blandford stated that he was getting an RSSi signal of 95-100dB at 1m. At no point have I seen this, regardless of the receiver, antenna orientation, colour of my underpants... etc. Call me simplistic, but if my rig is 10 -15dB down, then I am more likely to hit range issues.

 

What's everyone else getting, or am I looking at misleading data?

 

Graham

[Mike Blandford]

I just ran a few tests using a FrSky D8R-PLUS (FrSky D8 mode):

X9D+ with DJT module gives RSSI over 100 at 5 feet.

9XR-PRO with XJT module in D8 mode gives RSSI over 100 at 5 feet.

TX16S with internal MPM in FrSky D8 mode gives RSSI around 85 at 5 feet. (Yes it was fine tuned).

A couple of external MPMs in FrSky D8 mode give RSSI around 100 at 5 feet.

 

I've always suspected the MPM gives lower output power, than FrSky modules, when using the CC2500 RF chip. I have several MPMs and they all show lower RSSI, some more than others, with, in my case, the internal module of the TX16S the lowest.

 

Every 3db lower reduces the range by 30%, 15db down would reduce the range to one sixth.

 

Mike

[Graham Davies 3]

Thanks Mike, that looks pretty conclusive.

 

So in theory I can use a different module and still use my receivers? 

 

Graham

[GrumpyGnome]

9 hours ago, Outrunner said:

 

GG, do you use the voltage telemetry?

Yes, I use it for the tx pack now as all three are in ic models. I ALWAYS get a low voltage warning when I first switch on, but they're fine after that

[GrumpyGnome]

8 hours ago, Mike Blandford said:

Every 3db lower reduces the range by 30%, 15db down would reduce the range to one sixth.

Isn't that parkflyer range?

 

I'm not questioning your technical ability, but I'd have thought if that's the case we'd have lots of reports of models crashing due to range issues...... unless it's an 'unusual' tx/rx combo....

 

(I'll have to check whether I have this combo...)

Edited November 28, 2023 by GrumpyGnome

[Edgeflyer]

What about this combo?

 

[Outrunner]

1 hour ago, GrumpyGnome said:

Yes, I use it for the tx pack now as all three are in ic models. I ALWAYS get a low voltage warning when I first switch on, but they're fine after that

I think you mean RX pack, odd that you get a low voltage alarm initially 

[GrumpyGnome]

Yeah, rx pack!

 

I know, it's weird.