Best interference free 2.4 tx under ?350?

[Martin Harris - Moderator]

Posted by Brian Cooper on 25/09/2020 01:57:54:

I was asked to test-fly a new Wot 4 XL for a club buddy recently. It was (is) equipped with Multiplex equipment. . A couple of minutes into the flight, the ailerons reversed themselves. . . It was certainly a challenge to get it down, but the main thought going through my mind was, "what else will reverse before it lands?"

It was landed with no damage, and we reversed the ailerons back. The only thing we could attribute the problem to was my buddy having a mobile phone in his pocket. . Much head scratching. .....!!

. . . .

Spektrum DSMX has proved to be bomb proof for me for several years.

.

Wasn’t it a Multiplex transmitter which was proved to be prone to programming corruption back in the early days of debate over whether mobile phones were a hazard near the flight line? As far as I know, it was the only repeatably demonstrated example of a problem.

[David Hall 9]

There are a lot of cheap (and sometimes quite nasty) "compatible" receivers available, particularly for Spektrum protocols. There may be a tendency to blame the Tx make as problematic when it may be the Rx copies.

Although in my club, many members use one or two popular, cheap Spektrum compatible receivers, my own experience on the bench caused me to bin the two that I had. It wasn't the Spektrum system that was a problem, for me, it was poor PSU noise immunity (brown-outs).

[Frank Skilbeck]

Posted by Martin Harris on 25/09/2020 11:32:23:

Posted by Brian Cooper on 25/09/2020 01:57:54:

Wasn’t it a Multiplex transmitter which was proved to be prone to programming corruption back in the early days of debate over whether mobile phones were a hazard near the flight line? As far as I know, it was the only repeatably demonstrated example of a problem.

I maybe wrong but i thought it was one of the Futaba 9 channel sets. But some MPX programmable transmitters were around before the days of mobile phones, so may not have been designed accordingly.

I've got 4 MPX programmable transmitters (35mhz and 2.4 Ghz), Jeti DS12, Spektrum Dx6i, and also had a Futaba FF6 (35 Mhz), never had a mobile phone problem with any of them, nor a reception problem.

As far as I am aware at our club field we have never seen any 2.4 GHz interference (Multiplex, Spektrum, Frsky, Hitec, Jeti, Futaba, Detrum and Flysky), but have seen transmitter faults on a couple of Spektrums (early Dx8 and a Dx6) and a Futaba 6EX

But if you are worried about interference on 2.4 GHz, there's a couple of fliers at our club using Frsky Taranis radios with 900 MHz modules as they understand this has better range and is less prone to interference.

Edited By Frank Skilbeck on 25/09/2020 11:47:44

[Brian Cooper]

Posted by Martin_K on 25/09/2020 06:35:50:

Posted by Brian Cooper on 25/09/2020 01:57:54:

It was landed with no damage, and we reversed the ailerons back......

What exactly was changed? A logic setting configured in a software interface? Something controlled via physical switches?

Multiplex: Two channels changed their direction. Presumably something got into the computer settings and gave it a kick.  As luck(?) would have it, it was the two aileron channels (one channel on each aileron) which changed. . On future flights, it might just as easily be any other channels...... who knows..!!? . . However, in the great lottery which has presented itself, it is kind-of good fun wondering how many channels will still be working in the correct sense when the model lands.

.

I shall stick with my tried, proven and utterly reliable Spektrum DSMX equipment.  

.

Edited By Brian Cooper on 25/09/2020 12:30:16

[Ron Gray]

Simple logic says that if you want less risk of interference then move away from the congested 2.4GHz band, and move to 868MHz.

[Former Member]

[This posting has been removed]

[Former Member]

[This posting has been removed]

[MattyB]

Posted by Brian Cooper on 25/09/2020 12:27:53:

Posted by Martin_K on 25/09/2020 06:35:50:

Posted by Brian Cooper on 25/09/2020 01:57:54:

It was landed with no damage, and we reversed the ailerons back......

What exactly was changed? A logic setting configured in a software interface? Something controlled via physical switches?

Multiplex: Two channels changed their direction. Presumably something got into the computer settings and gave it a kick. As luck(?) would have it, it was the two aileron channels (one channel on each aileron) which changed. . On future flights, it might just as easily be any other channels...... who knows..!!? . . However, in the great lottery which has presented itself, it is kind-of good fun wondering how many channels will still be working in the correct sense when the model lands.

I shall stick with my tried, proven and utterly reliable Spektrum DSMX equipment.

A sample of one does not really prove anything though does it?! My Dad and I have >1000hrs of flying on Multiplex TXs, and I’m a member of one of the biggest soaring clubs in the UK where Mpx transmitters were the most popular brand in the 90s and noughties. I’ve never heard or seen such an issue occur on Mpx gear (or any other for that matter) so it hardly seems like a factor to choose your TX onon. I have however seen numerous (>5 across two clubs) burnt out Spektrum RF boards, though the rate of those occurring does seem to have slowed in recent years.

By far the biggest causes of issues remain power supply failures, poorly installed antennas and dumb thumbs that were blamed on radio failure. Avoid these pitfalls and any FHSS based system will work fine 99.999% of the time.

[ken anderson.]

meanwhile getting back to martin's opening question....has any of this helped martin?...because this thread is heading as was predicted into this set V the other set's.....

ken anderson...ne...1..... dept.

[martin collins 1]

So i see, reason for asking is that our club seems to be having `interference issues` in two spots in the flight area, these are not always there and intermittent but have taken out half a dozen planes since the lock down was lifted, yes most of them were Spektrum BUT that is what the large majority at our site fly. The last one i saw was on Hitec TX/RX and it was in a bank that just continued into a roll and dove into field just outside our patch, there was no response from the tx. The remains worked fine once retrieved, it was not a stall, the plane was carrying a good turn of speed. I fly with a gen 1 DX9 and have done since they first came out and have (touch wood) never had any issues although i have found that it will not work with the latest generation of Lemon receivers, it binds but when switched on to use there is no connection to the tx, i tried re binding and have even bought a second one that behaved in the same manor. both were returned and money refunded as it was eventually put down to incompatibility with the gen 1, gen 2`s do work with them. I have taken up building my own models over the last 12 months and some of the scale ones have taken quite a bit of work and though i do say so myself look really nice, but with the recent problems i am reluctant to fly them in case i get `shot down`. I have been contemplating moving to a gen2 Spektrum and DSMX receivers over my DSM2 gear but someone who purports to know what he is talking about is telling me to buy either Futaba or Multiplex cockpit, he indoor flies in the winter and tells of multiple problems even on the new Spektrum gear. The price of the Multiplex and the cost of the rx`s is somewhat off putting as i have 20 flyable models which will mostly need new rx`s (i have about 5 on DSMX rx`s). So before i spend some money i thought i would hear what others had to say.

[Denis Watkins]

Reading with interest

Round 2 of the Bashing thread

Don't get drawn in to " Interference Paranoia " Martin

As already stated, poor installation, chargers undercharging, and faulty "New " battery packs, all play their part.

[Frank Skilbeck]

Martin, from your description it may not even be 2.4 ghz interference but some other high power electromagnetic "beam" which is swamping the receiver electronics and causing a lock out. Some receivers will be better at handling this than others, but then it's not down to the protocol used.

Did any of them have telemetry feedback telling them what the signal quality was like? My Jeti and MPX systems both have this and the only time I ever see drop to less than perfect is when I've landed a glider out of sight when I've gone back a bit to far on the hill when landing, so the ground is interrupting the line of sight But then again there are no cheap 3rd party receivers available for either of those systems.

[FlyinBrian]

I have one of the early JR DSX9 systems which used the Spektrum DSM2 protocol, it is now 11 years old, I have used JR Rxs, Spektrum Rxs and Orange Rxs all have been fine. No glitches or failures!

The only crash I suffered was due to the Rx battery going flat in the air which can not be blamed on the radio. I checked the voltage after the crash and the battery showed 4.2 volts with no load.

I have also been using a Futaba T14SG for almost 2 years with mainly Futaba rx but also a few FrSky rx. Again no issues at all.

Our club uses Futaba, FrSky, Hitec and Spektrum kit and all seem to perform well.

Ensure you install the equipment properly and use adequate capacity batteries and all modern kit works well.

[Former Member]

[This posting has been removed]

[Stephen Smith 14]

Posted by Ron Gray on 25/09/2020 12:54:23:

Simple logic says that if you want less risk of interference then move away from the congested 2.4GHz band, and move to 868MHz.

My jeti comes with 2x 2.4 transmissions plus a 868mhz back up if I add a rsat 900 to the receiver 

Edited By Stephen Smith 14 on 25/09/2020 18:47:30

[Martin McIntosh]

I too still fly with DSX9, DSM2, of which I have three operating JR 921`s, various Spektrums and a lot of Orange Rx`s. The only time I got shot down was at a well known event when three of us went in at the same time, me on DSM2, another on Futaba and the third on FrSky so really none of these are immune. The cause was never established.

Most of my fellow club members use either Spektrum DSMX or Futaba, and I know of no problems with the latter. The Rx`s are, however, rather expensive compared with most of the opposition.

[flight1]

to answer the op question is that most 2.4 systems currently are good and reliable most problems are due to the istallation/broken or placement of arials and the most common is battery(I had a battery go down last weekend and telemetry saved the day aborted take off as the tx screamed 3.7v rx voltage and now i get to fly again my lovley scale luton minor)

So if on budget(like me) your choice of make will be based on RX costs so choices are

one of the Frsky radio's which you can plug a module in back for your legacy RX's

FlySky Paladin PL18 (very under rated and under expposed)

Radiomaster T16s multipotocol fantastic ( not as refined as my Horus x12s) the future

and please note if you have a frsky om optx you can have a R9M 868MHz Module and compatable reduntancy rx and the 2.4 rx for extra security on two frequancy bands like jeti in a way)

Edited By flight1 on 25/09/2020 19:04:44

[Ron Gray]

As I understand it with Jeti you must have the 2.4GHz as the primary, 868 can only be the redundancy (correct me if I'm wrong). Not really an issue but the TXs like the FrSky and Radiomaster ones with the 868 module can have that as the primary or only frequency.

So, keeping within the OPs budget, well for a tad over it you could have the really excellent (build quality and components) FrSky Horus X10 with the 868Mhz module and for a lot less money (£200!) the nice Radiomaster T16S with 868Mhz module - just as flight1 noted above. Unfortunately even the cheapest Jeti (without any of the upgrade options) comes out over the budget and the cost of RX........Nice bits if kit though.

[Geoff S]

I think with most (all?) radio systems the cost of the transmitter is a relatively minor issue because you only but one. It's the cost of receivers if you have multitude models and choose to fit and leave a receiver in each one.

Geoff

[Ron Gray]

Good point Geoff.

[Chris Walby]

Irrespective of TX and RX manufacturer (as they are likely to be all tested to death in the development lab) is the problem to be far more likely an external influence?

Ok some might be better than others with a particular type of interference, but if the interference is very powerful then it will make little difference which manufacturer made the equipment? Are the manufacturers designing jamming equipment looking to be specific or just knock everything out of the sky, so if then is an external interference likely to effect all manufacturers sets if its powerful?

PS - That's of course based on the assumption that a completely different "spare" frequency is not used.

[Former Member]

[This posting has been removed]

[MattyB]

Posted by Doc Marten on 26/09/2020 11:08:05:

Posted by Chris Walby on 25/09/2020 22:30:57:

PS - That's of course based on the assumption that a completely different "spare" frequency is not used.

35Meg is exclusive to RC flying and now clearer than it ever has been, why look at new frequencies when we already have one?

It's mainly because of OpenTx, Rx pack voltage and RSS telemetry that I use 2.4gig if I'm honest.

You just answered your own question! Who wants to give up those things to go back to a time where frequency control was manual and certain colleagues would hold the peg you wanted hostage! No thanks. I've had nearly 10 years of 2.4GHz usage now without any issues, the last place I would go is back to 35MHz at this point. Besides, from what I understand from the few people I know still devoted to FM, crystals are as rare as hens teeth these days...

[Former Member]

[This posting has been removed]

[Frank Skilbeck]

Posted by MattyB on 26/09/2020 11:26:06:

Besides, from what I understand from the few people I know still devoted to FM, crystals are as rare as hens teeth these days...

True but if you have synthesized transmitter and receivers then crystals aren't an issue. I'm still flying several IC models on 35 Mhz, where I don't really need telemetry, using a 15+ year old MPX Cockpit Sx and recently acquired a hardly used back up for a £35