JR DSX-9 2.4

[Dave Wilshere]

Guys

I've had the JR DSX-9 a couple of days now and testing shows it to work as expected. After all it's the same system as Spektrum and now made in JAPAN in JR's prime factory.

I know a lot of people were waiting for a dedicated system and now they have a choice.

You can data transfer from a 9X II 35mHz into the DSX 9 and just change RX.

Dave Wilshere

[Bladerunner]

So how 'bout a review?

[David Ashby - Moderator]

MacGregor have promised us one soon so stay tuned..........

Dave - Hi and welcome - good to hear the DSX-9 is working well.

[Dave Wilshere]

I can't review something I sell.

 Anyway, it's a 9 x II with built in 2.4. programs and works as a 9 x II just on 2.4!

 David, thought I'd see what was going on here!!

 Regards

Dave

[Roy Hill]

Dave,wecome,it all goes on here,its a magic forum,hope to hear more from you,regards Roy. 

[Dave Wilshere]

Roy

Guessed it would, it's part of the happening magazine!

Dave

[David Ashby - Moderator]

They're in the shops, does anyone have any new user experiences/comments on the JR gear or is it identical to the 35MHZ version apart from the frequency output....and a stubby aerial?

[Andy Sayle]

I'm slowly getting to grips with my DSX9, it is a hell of a step down from the flexibility of the Multiplex radio I have been using for the past few years though.  Things like setting up the dual rates are a bit of a change for me, as are the fixed switch definitions.  It does seem to be able to do everything I need for now though, although I am not sure about my Kite aerial photography rig just yet 

From looking at the manuals, it does seem to be pretty much identical to the PCM9x2 in terms of software, programming and switch layouts.  The manual supplied with mine was actually a PCM9x2 manual, with a DSX9 additional 8page booklet.

I have to admit though, despite my love of the Multiplex programming philosophy, the JR radio does feel nicer, and like it is more solidly built.  The stick units are nice and smooth, the switches all feel nice and solid.  One thing that is missing (IMHO) is a nice bright LED to indicate the set is turned on.  I may have to add one to do this job at some point in the future.

Cheers

Andy 

  

[Dave Wilshere]

Andy

Welcome to quality

 It's not as flexible as some of the German radios, but it gets close, it much more user friendly and like you say has the best sticks in the business-A Futaba World Champion told me that!!

Dave W

[Andy Sayle]

To be honest, the reason I have bought the DSX9 radio, is to see what the fuss is about!  I actually did a bit of "spektrumification" to my Multiplex Evo, and I have a Spektrum Air Module running in that which is working great, and I have been using it for most of last season, as well as over winter.  My intention is to do a bit of a comparison, and decide which one to keep.

I've just thought of something else that I am missing from my MPX radio, and that is assigning a countdown (or count up!) timer to the throttle stick, to monitor how long the throttle has been open (or shut!) more than 10% (or any percentage for that matter).  Although, the two rotary controls on the sides of the DSX9 are a rather nice touch!

I'm still making my mind up, but at present the MPX radio is coming a close (very close!) second, primarily down to the feel.  If the DSX9 can do the more oddball stuff like for my camera rig, and a few other "projects" then the Evo radio might be for sale!

Cheers

Andy 

[Mike Healy]

Sorry, I somehow missed the existing thread as I.ve been skiving off in France for a few days, and missed out on the launch - silly me started a new thread - please excuse!

[Former Member]

[This posting has been removed]

[Chris Marshall]

After chasing City link round the county for a couple of days I finally got my hands on one. It seems to be all I was expecting and a ground range check in the field out the back of the house seemed fine. But, there is a buzzing which is quite noticeable in a quiet room, though probably not at the field. I have taken the back off and the noise is actually coming from the sounder. It is not present when in System Mode. Does anyone else suffer from this? I am wondering if it is just a bit of poor layout, ( i.e a design fault, resulting in pickup of the encoding) and I am going to have to live with it, or should I send it back. I am reluctant to do so, having waited this long, but if it is faulty then I have no choice. I will contact MacGregors for advice also.

[Andy Sayle]

I have found that happens with pretty much all of the Spektrum radios (and my DSX9 too).  The rf module in the 2.4Ghz sets (spektrum based) is actually not transmitting continuously.  Instead, it transmits two bursts of data at approximately 45.5Hz.  The power required when actually transmitting is quite high, and if you look at the current draw of the radio, the peaks that correspond to when the module is transmitting are around 500mA or so (dropping to around 100mA when not transmitting).  These peaks are pretty much identical to the buzzing sound coming from the sounder, and I beleive that they are caused by either poor layout and design of the circuit, or the sounder picking up interference from either the 2.4Ghz module transmitting, or the fluctuating current (that is quite high) flowing not too far away from it.

It doesn't happen in system mode, because the RF is disabled when in system mode.

I had my DSX9 open last night to adjust the stick tension, and I couldn't resist a little investigation with my oscilloscope.  The current draw of my DSX9 is around 190mA average, peaking at around 440mA when transmitting (see above).  With the rf off, the current draw is much more stable at around 90mA or so.  The communication between the main processor and rf module is also quite funky.  It is basically sending a data packet once every ~22.5ms, and consists of a line containing what appears to be an index pulse, a line containing a clock signal (burst of square wave 2.052ms per cycle or roughly 500kHz repeated in line with the index pulse) and a data line which sends a packet of data in time with the clock signal.  The data line can be seen changing when sticks are moved.

I'm getting bogged down in the techy stuff now anyway, on to a more sensible question.

On my DSX9 there is a small bit at the top right of the display that says "Unadjust".  I can't find mention of it in the manual, and playing around with the settings/switches etc doesn't make it change, so does anyone know what it is for?

Cheers

Andy 

[YakMad]

After seeing the DSX9 and reading this thread the dreaded urge to buy came over me and I have just placed an order, I have to say I was never a fan of JR, the programming always drove me mad which is one reason I stuck to Futaba, but had a look at the US manual for the DSX9 and it seemed to make sense  (I hope it will make sense when I get the Radio), anyway the mention of the buzzing noise has me a little dissapointed, although I read on some of the US forums that some guys are opening the Tranny and putting a piece of foam over the sounder to lower the tone of the programming BEEPS (they seem to do their programming in the middle of the night ????????) I wonder would this foam mask the buzzing although I think JR should have sorted this out before the Radios were shipped.

[Andy Sayle]

I don't think the buzzing is that much of an issue to be honest.  It is not what I would call loud, just noticeable when in a very quiet environment.  As for the beeping coming when programming, then yes that is a little on the loud side!

I've found out what the "Unadjust" bit is too.  Apparently it means that the radio sticks haven't been calibrated, and apparently it needs to go back to Macgregors to be properly calibrated.   Fun and games!

Cheers

Andy 

[Chris Marshall]

Andy,

I was considering attacking my set with a scope but you have saved me the trouble! I knew that the RF was not continuous, so I suspected that it was break through, either via power lines or RF radiation, but I was slightly concerned that it was a marginally stable switch mode supply, but I haven't spotted any in there, although I have not had a really good poke around yet. I would agree that the noise level itself is not an issue, my concern was that it was symptomatic of another problem.  Macgregor have suggested sending it to them for a check, which I may do for peace of mind, but as it is present on other sets I may just live with it. The bleep is pretty loud, so a bit of foam to mute it may not be a bad idea, and the buzzing would then be undetectable. As the frequency of the buzzing is significantly different to the bleep frequency I may investigate some sort of passive filter ( electronic rather than mechanical, to bolt on the back) but probably not until it is out of guarantee!  I haven't noticed the 'unadjust' message myself, but will have a look for it now, if it's there then it sounds like it has to go back anyway.

Yakmad,

I'm sure you won't be dissapointed with your DSX9 once you have it, everything else about it is fine, and as Andy says, the buzzing is not actually an issue.

Cheers

Chris 

[Andy Sayle]

IIRC all the power supply chips on the DSX9 are linear regs.  The RFboard has got a chunky 3.3v linear reg that supplies the Spektrum module, and it is fed directly from the battery supply.  The main board of the DSX9 that has the processor on, seems to be mainly 5v levels, but I didn't see what sort of power supply that it is using.  When in system mode (I.e. RF not transmitting) the current draw is less than around 100mA, so I would expect to see a linear regulator to drop from the battery supply to 5v, purely on the basis of cost and simplicity...  I'll double check at some point over the weekend though.

Cheers

Andy 

[Chris Marshall]

I think I'm not going to bother sending it back now. Having had another play this evening coupled with the range check the other night I am confident all is well. I would agree with your expectations of linear regs. Part of the documentation advises against  replacing the battery with a 3S LiPo, and state that a charge of the NiMH should last around 14 hours. That would imply mean currents around the levels you are talkingabout, making linear regs practical and cost effective. I take it you are involved in Electronics professionally? As I am. Will be interested to hear what else you discover about it. Spektrum have always talked about a significant advantage to DSM over frequency hopping without justifying it. My suspicion is because it is possible to get the data rate fast enough with a 10% duty cycle, and because of the spec only regulating mean power, it is possible to transmit at a much higher level than the 100mW figure, thus improving the sig/noise ratio. If this is the case then it does give a significant advantage over frequency hopping systems using only 100mW peak.  I don't know if this is the case, all the manufacturers are very vague about what they are actually doing and why, so it is hard to really know. I don't think it matters as all seem to be an improvement over 35MHz, once the different oprational requirements are understood.

Cheers

Chris 

[Andy Sayle]

Hey Chris,

That's right, I am involved in Electronics professionally.  Well, strictly speaking I am a Design Engineer, and my main area is mechanical (mold tool, product, concpet, form tool, jigs and fixtures all sorts!) but the producs I design are intelligent digital sensing systems, so over the last few years I have picked up a fair bit of electronics knowledge.  Enough to be dangerous anyway!

I think with the 3s lipo thing, it is all about the slightly higher under load voltage.  Most lipo packs can hold a good 11.5-12v under the loads seen in this transmitter, whereas the nimh pack will be closer to around 10v.  The linear regs used are not too well placed for good cooling (no airflow, no large heatsinks or copper planes on the PCB nearby to dissipate the heat), so the extra few mW of power being dissipated by them is obviously raising their temperatures enough to shorten the working life enough to be an issue in some cases.

The advantages of DSM over true frequency hopping is a very debatable point when thinking about the low data rates involved here.  I personally think that the frequency hopping transmission method does give a slightly more robust link, providing it is using a large portion of the band available.  However, I went with the Spektrum/JR stuff in the first place because of the choice of receivers available, and have found it has worked faultlessly for me to date.  For that reason, I will stick with it   Interestingly, I think the main benefit doesn't come from whether 2 channels are chosen by the set at startup (DSM) and fixed, or true frequency hopping.  Instead, I think the benefits of this technology come from the wideband transmission as opposed the the narrowband transmission used previously (i.e. each "channel" being around 1Mhz wide, as opposed to a few KHz on 35Mhz).

Cheers

Andy 

[Chris Marshall]

Andy,

I think I agree with all of that. I suspect that the main reason for two channels is so that it can be claimed to be a frequency hopping system, which allows 100mW instead of 10mW, which is sort of what has been said recently on the Macgregor site. 

I have come from the other side as it were, as I am an electronic designer, but have ended up doing a fair amount of mechanical design, as you say - enough to be dangerous!

I notice that the receiver has two battery ports, but the docs make no mention of this- unless I have missed it. Does anyone know how they  work, i.e. can you just plug two packs in, and active switching takes care of them, or are they just alternatives for a single pack? I will have to explore and see if they are just parallel wired or there is something more subtle going on.

Chris

ps I am both Chris Marshall and Chris Marshall 2, I'm not sure why I have these aliases, I have tried to get rid of one but without sucess so far. I think it may be because I have two different yahoo logins. 

[Peter Roberts]

Hi just reading the thread for the first time and notice Chris' query about the data ports. 5 mins ago I read another Timbo thread dealing with battery ports on Spektrum receivers which suggested that one is designed as a data port for flight logging and the other as a JR standard battery and binding port.

When using Spekkys with electric BEC though you have to plug the binding plug into battery port battery into any other position - as i understand it all the +ve and -ve pins on the receiver are connected as a power bus so it shouldn't matter. However interesting that Spekky recommend 6v batteries rather than BEC's.

 There you've exhausted my technical knowledge which is probably wrong anyway. I've been playing around trying to fit an AR7000 into a small funjet and ended up mounting the rx upside down in the fus with the short antennae poking through holes in the fus so they were able to be fully extended!

Hope this has been of some help,

Peter