Lemon and Spektrum RX's

[Chris Walby]

I had a nagging thought after my TN Ta154 crashed a couple of times at the beginning of the year, put it in the naughty corner and moved on with some IC stuff.

Roll on 6 months and I have a new model so bought a nice new 10 channel Lemon with satellite. I thought I would pop up to the flying field with the TX (DX8 gen 1) RX and loom with some spare servos attached.

It binds ok and I get 30 metres away (as TX instructions on reduced power), but if I turn my back to the RX it looses signal

Back again today and with my son's DX8 and a AR635 + the Lemon stuff

The Spektrum AR635 RX on either TX works +45 metres

Lemon RX works facing at 30 metres in test mode

*********

So I revert to full power and get someone to watch the servos on the bench, then off for a walk down the field. Just before I get to the end of the field..RX loses signal

This is about the same distance as where the Ta154 went in.

***

So I don't think its a TX power issue as both DX8's work with a AR635 on reduced power at 45 metres + both TX's work ok with all the other Spektrum RX's I have.

Question, is this this specifically a DX8 gen1 and Lemon RX issue?

Is it a worry that the RX passes the reduced power test, but not the end field test?

PS I have Lemons in small foamy models and all seems ok (but I don't fly outside the field with them).

Lastly, can we not have a slagging Spektrum posting (its been done before) please

[Richard Wills 2]

Personally never had a range issue with the 10ch Lemon, but have always noticed the signal loss on any RX at 30mtrs through the body when range testing. Only way to check if the range issue down to the Lemon RX, is to test another one the same way.

[Colin Carpenter]

Cant speak for the Lemon 10 Ch Rx but we have lots of 6 Ch and 7 Ch Rx on DX 8 G2 and DX 9 and no range problems but our fields not the largest ! No more than 200 yards each side . Colin

[Chris Walby]

Hi, double checked the Lemon RX in the Ta154 and its a 10 channel as well. What got be thinking was on the all but last time the Ta154 parked in the snow the lipo was still connected and the RX red light was flashing (normally the lipo would self disconnect doe to the rapid stopping!

I am curious if the issue is just DX8 gen 1 to Lemon 10 channel or a wider issue (appears not).

I'll test the Ta154 RX and see if it does the same + see if someone else has a Spektrum TX they don't mind binding to the Lemon and try it with that.

PS After the HABU went in (fail safe) and I did a search on the web, it seems that DX8 gen 1's have an issue with AR500 RX's, odd as I had flow the HABU lots of times, but not in very high humidity (ok it was about to rain) or quite so far away.

[Keith Sharples]

I use a lot of lemon with and with out satellite's with a Spektrum DX8 Gen 2 . I have had no problems at all. I have noticed with the model on the deck and walking 30 meters all is well, get towards 40 and it starts to break up (to be expected I suppose). I know there was some problems with the DX8 gen 1 but I'm not sure what. It know it was all sorted in the Gen 2.

[Former Member]

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[Chris Walby]

Keith and Ikura,

I will test everything up at the field, but I think I have a issue with the DX8 gen 1 and the Lemon 10 channel RX when used together.

The choice is to hunt out (non fake) RX's or buy a new TX, ok a new TX is a lot of money, but my current model is a comparable cost and I would be gutted to lose it because of using old/non compatible kit.

Next question DX8 gen 2 or DX9 and what makes the DX9 worth £100 more (don't buddy or use telemetry)

[Trevor Crook]

I've never tried a Lemon rx with my Gen1 DX8, all of my rx's are Spekky except for a couple of Orange. One is an indoor type and is fine, the other is an 8ch DSMX. This is in a 2m motorglider, and gives a slightly lower ground range test result than the Spektrums, but is fine in the air to the limit of my vision. Is the Lemon DSM2 or DSMX?

I bought most of my rx's when they were a lot cheaper than they are now - you could get AR8000s for less than £40. I see there are a new range of receivers with internal antenni at reasonable prices - about £35 for the AR620.

If you are considering a new Tx and don't want frills, the DX8e looks good value and had a good magazine review recently. I'll be using my DX8 for a while yet as it talks to the few DSM2 rx's I've still got.

[Chris Walby]

Trevor, thanks for the post and like you have a few DSM2 RX's in smaller models + I have a DX8 and my son has one as well, I could push all the DSM2 RX's onto his TX and go for the DX8g2 or DX9 (still can't see why its worth 100 quid more).

Heading to the field for more testing (before the next 6 hours rain sets in) with both Lemon RX's then its off to the building board!!

[Former Member]

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[Former Member]

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[David Davis]

Posted by Ikura on 26/08/2018 09:14:37:

... If I was still using Spektrum I would probably be a bit wary of buyting a DX9 because it is getting a bit long in the tooth...

Really?

I bought one of the first DX9s and mine still works perfectly.

[Former Member]

[This posting has been removed]

[Robert Putley 1]

I have several LEMON RC STABILSED RX 's. It is worth pointing out that in addition to being able to select the modes via the TX it is also possible to control the gain from your transmitter

[Keith Sharples]

Ok calm down everyone. Ikura I think David Davis was making a comment thats all, as in it's still going strong after some time with no problems.

Steve Js point about having diversity antenna (2 at 90 degrees of each other, 1 in the sticky up twig and the other in the rear handle) on the DX8 gen 2 and DX9 is very valid re transmission and of course the reception at the model end. It may be some of Chris Walby's problem having only 1 in the sticky up twig thing?

[Trevor Crook]

That's a good point on the antenna - could the Lemon rx be more sensitive to the antenna pointing near it?

[Chris Walby]

Trevor and Robert, I don't think its an antenna issue because I don't have any range issues with my Spektrum RX's and when Dave flies the Vulcan he's twice to three times further away with the same TX (Spektrum RX).

I was on my own at the field this morning so limited to what I could do, but I did try the Lemon RX with a DX6 on range check and it passed with me in any orientation at 30 meters and looked ok at 40 meters (facing).

I still need to walk across the field and check the real range with the DX6 + check the Ta154's Lemon RX with the other DX8 and see what happens.

I don't think it a case of something is faulty more an issue with compatibility (and an pair of old DX8's) as its not a problem for the DX8 g2's.

Thanks to everyone who has helped, much appreciated

[Chris Walby]

I think this could be brought to a conclusion following this afternoons visit to the field.

New Lemon RX and DX8 + Old (Ta154 Lemon RX) and BX6 both walked the entire length of the filed (but bear in mind a usual circuit is double to triple this distance)

New Lemon RX and DX8 lost signal (TX works okay with lots of other Spektrum RX's)

Old Lemon RX and DX6 showed no loss of signal

The conclusion appears to be that the DX8 gen 1 (either of them) does not work well with Lemon 10 channel RX's, but seems okay with 6 channel versions.

Thanks to everyone who chipped in, cheers and looks like a DX8 g2 could be on the birthday list

.

[Peter Beeney]

I related this story in a previous thread many moons ago; now I’m wondering if it might again be of some interest here.

We do a long range occasionally because we reckon this is fairly foolproof inasmuch that we reckon that if the radio generally has satisfactory range on the ground it’s most likely be ok in the air as well.

This consists of placing the rx, battery and two or three servos on a metal folding chair at the strip and then taking the tx to a point across a shallow valley 700 metres away; but still direct line-of-sight. The tx position is then very close to the corner of a small wood. If the rx is in a model it’s stood on the ground but moved around to suit. We first tried this when a colleague converted a 35 meg Futaba 9 channel tx with an Assan 2.4 ‘hack’ module. The rx aerial is just three quarters on an inch long and sticks straight out the back and we wanted to see just how good it actually was. Just to try and complicate the issue a little more we place 3 transmitters, all switched on, underneath the chair.

Comms link is by mobile phone, (another possible hazard, maybe?), and the tx is then tried in every configuration, including a lot of both aerials pointing directly at each other. The rx is moved to different positions as well as the tx. Plus a quiet five minute period of no activity to check for interference from under the chair.

We now consider this to be our benchmark range check.

I have to say that so far this little this little strategy has always been a 100% success; and it also included a Spektrum DX5e that I bought long ago as a buddy box. And as it so happened the Assan kit behaved itself faultlessly too.

As an aside I can add that I also tried the Spektrum rx in a powered glider as an example of how not to do an installation, such as servo and battery leads twisted together with the aerials, wrapped around the rx and then just bundled willy nilly into the fuz. I tried a few different combinations of this and eventually I was flying was on the limit of visibility but I never did have the slightest indication that there was anything other than than just a perfectly reliable radio link.

Actually we don’t really do this stuff too much any more, I think we’ve long concluded we don’t get many incidents in the way of range or installation problems anyway. The occasional crash can invariably be explained by some other reasons, such as disorientation or power failure of some kind; but that’s a another story…

However, one thing I think I may be able to say with some certainty, I suspect that if you ever find yourself flying at a distance of 700 metres with anything other than the largest of models then you may find your immediate attention could well be focused on the one of adequate vision rather than radio range…

…it’s already out of sight…

PB

[Chris Walby]

Peter, Thanks for the information.

I think the fact that both DX8 g1's and Lemon 10 ch don't work at 30 metres (with my back turned) on reduced power and other RX's (Spktrum/Lemon) work okay + DX6 and same Lemon 10 ch RX works at 40 meters (reduced power).

Then DX8 and Lemon 10 ch (both) fail before I get to the end of the field (250 meters), but DX6 is okay with Lemon 10 ch RX + DX'8's and Spektrum RX's work okay outside the field proves the TX's are okay.

PS the Ta154 went in (more than once) at the same distance as both RX's have a loss of signal, just too much coincidence when the RX is hanging from a wooden bench and the servos stop moving!

Bad news finding out, especially for the 1kg Ta154, but good news before I maiden my 7kg twin!

PPS I have experienced a fail safe 1/2 way through an inverted 1/2 loop..as the edf winds down and you have no control, you can only wait for it to stop in the ground.

[David Davis]

Posted by Ikura on 26/08/2018 09:39:03:

Posted by David Davis on 26/08/2018 09:25:40:

Posted by Ikura on 26/08/2018 09:14:37:

... If I was still using Spektrum I would probably be a bit wary of buyting a DX9 because it is getting a bit long in the tooth...

Really?

I bought one of the first DX9s and mine still works perfectly.

If you read what I wrote I just said I would be wary of buying a DX9 now because it is getting a bit long in the tooth. It is just an observation and no need for the typical defensive stuff that always comes up when ever the word 'Spektrum' is mentioned.

I did not write, or imply, there is anything wrong with the DX9 and no one is criticising Spektrum.

I was not being defensive about Spektrum in general or about my DX9 in particular. Far from it infact. I used to have a Futaba FF7 which I owned for twelve years without a problem. Then I bought a Spektrum DX6i. After some months the rudder trim failed. This was a common fault on the DX6i. The component was replaced foc and sent back to me by return of post.

Then after a couple of years use the DX9 stopped transmitting.The screen lit up but there was no signal. By this time Spektrum had closed down all of its repair facilities in Europe except for the German agency. I sent my transmitter to Barsbuttel where it remained untended for several weeks because the German repair facility was inundated with repairs and did not have the staff to cope. To misquote an expression heard on building sites, "What bloody manager did that?" Even the Germans got fed up and sent it to the USA where it was repaired the next day, sent back to Barsbuttel thence to your humble servant after its world tour. I was fortunate, having retained the DX6i, I was still able to go flying.

Finally last night I was finishing off an ARTF electric powered foamy trainer called a "We Can Fly." I do a fair bit of instructing these days, I have a small fleet of trainers, I use the DX6i as a slave and have the use of a DX5 Mode 1 transmitter, which is also used as a slave, as the majority of pilots hereabouts are Mode 1. Having selected a new model memory I found that everything worked except that the elevator servo only gave partial travel. No amount of adjusting the servo travel function enabled me to get anything like an acceptable amount of elevator movement. I removed the servo and checked it on a servo tester. It was fine. I re-installed it, selected a new model memory and everything worked normally. I'll test fly the model later on.

This is not the first time that this has happened. There is another memory which I have marked "Do Not Use!" for a similar reason. However, the transmitter has 250 memories and I'll never have that many models. What I do have is a fair bit of money tied up in Spektrum equipment so even though my DX9 is "long in the tooth," and not as reliable as my old Futaba FM transmitter, I will persist with it.

The Spektrum DX9 has all of the features which I can even ever imagine myself requiring.

What are you looking for in a transmitter Chris?

[Peter Beeney]

Chris Walby @ 28/08/2018 11:58:08

Many thanks for your reply, Chris.

I remember in the first instance we were surprised, nay, rather more astounded probably, with the quality of the Assan radio and it’s shorter than short receiver aerial, but after a few other similar examples and results we accepted it as more or less the norm. Right back in the early days of 2.4 I did read that some electronics bods had tested a radio up to 1.5km still maintaining contact ok; however, again that was direct line-of-sight, anything in the way and it all went a bit blank.

I’m sure I’ve always been very lucky because I seem to have had very few problems with actual radio failure, right back from the days of single channel. With the greatest respect I think if my radio started playing up as yours seems to I would want to dig into this fairly sharpish too. I have to admit I’ve never tried a low power range check, I’m sometimes a little sceptical by nature, this probably dates from way back in the days of megs rather than gigs when I found the then ‘aerial down’ short range check was by no means infallible either.

There have always been anomalies, a long time friend and flying mate using Spektrum from it’s arrival on the scene together with small very fast foamies had the odd but persistent unexplained crash. This when Spektrum was a bit at the forefront of many discussions. For various reasons I was again sceptical about the BECs in many speed control units back then so eventually he shoehorned a small rx battery in all his models, (whenever possible), and connected it to the rx just to back up the BEC supply. He later remarked that it had cured all his Spektrum problems; and he still uses a backup rx battery…

We do seem to have some discrepancies with the distances involved, on a good weather day we’ll try a few radios out using the same MO as you, just walk away with presumably the model on the ground and see what sort of results we get.

In all honesty I’m not entirely sure about the 250 metres ground range you mention but we will have to try it before making any firm comments.

Good luck with getting this sorted…

PB

[Chris Walby]

David,

The DX8 g1 does almost everything I need (apart from two throttles both with throttle cut (which almost works!)).

What I can't quite see is why pay another £100 pound more for a DX9 compared with a DX8 g2?

I have tried telemetry but its a faff to move between aircraft (and does no tell me much with a DX8g1 unless you are looking at the screen!) and now I am heading IC its not so important! ...Its gone quite..must be a dead stick!

I'll keep my son's DX8 g1 for the DSM2 RX's and resolve the Lemon 10 channel RX issue with a DX8 g2. The alternative is to only buy Spektrum RX's (after buying two or three I could gave bought a DX8 g2 and have a nice shiny new TX).

Peter,

I am happy with the DX8's I have, only one other problem in 1210 flights over 4 years (excluding the other Lemon 10 channel RX which displays the same issue).

So to finish off, what's the difference between a DX8 g2 and a DX9 that justifies £100 (if I don't need the 9th channel)?

[David Davis]

If the DX8 had been available £100 cheaper than the DX9 when I bought my DX9 I would probably have bought one!

[Kim Taylor]

Posted by Chris Walby on 28/08/2018 22:54:52:

David,

The DX8 g1 does almost everything I need (apart from two throttles both with throttle cut (which almost works!)).

What I can't quite see is why pay another £100 pound more for a DX9 compared with a DX8 g2?

So to finish off, what's the difference between a DX8 g2 and a DX9 that justifies £100 (if I don't need the 9th channel)?

This is a useful chart showing the features of all of the current range of Spektrum radios **LINK**

The biggest differences are the actual case is a different size / shape, so one may suit you more than the other, and the 9 has sliders which you can assign to any (I think) channel - no particular use to me, but I think that the sailplane guys use them.

I've got the DX8 gen2, which I'm more than happy with at the moment and use either genuine Spektrum or Lemon receivers, again more than happy with the performance.

Kim