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Old Mar 12, 2013, 09:08 PM
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JR XG-8 Owners Thread

This radio is quite similar to the XG-11 but there may be enough difference to warrant a separate thread... and I'm thinking there may be XG-11 owners who wish their thread remain specific to the XG-11 only. It might however be beneficial for XG-8 owners to follow the XG-11 thread as I've learned a good bit about my XG-8 there.

I've been an XG-8 owners since December and am a late comer to 2.4, wishing to wait until the dust settled a bit on 2.4 technology. That might be a significant point, that XG-8 owners may more often be those entering 2.4 technology rather than upgrading within it. That might be less true for XG-11 owners, however.

That dynamic might mean that XG-8 owners suffer a little greater from the learning curve, having never owned 2.4 before. I was a bit sluggish with the curve... but after a couple of months am beginning to feel more confident with the radio... that is... until today.

I've fitted thirteen planes with DMSS receivers as part of my fleet upgrade. My reasons were two fold. First, the money existed right now for the upgrades and second, we've had some pilots that when flying both technologies (2.4 & 72mhz), either forgot to extend an antenna on their 72 mhz and lost planes or forgot to get a frequency pin for 72mhz and on one occasion very narrowly avoided shooting another flier down. If the airborne pilot had not hollered quickly and loudly and the offender had not turned back off immediately... a large and nice plane would have been lost. I hope to avoid those pitfalls so upgraded all but a few planes that rarely get flown.

What happened today is part of the learning curve. While I attempted to make a proper installation of the rx antennas, I failed to insure that all wires would stay clear of them. The plane was/is an Ultra Stick Lite, which has a quad wing setup with four servos. The extensions coming out of the wing are bundled together with tie wraps so the four extensions bundled together make a good size wire harness. When installing the wing or when flying, they became positioned against and running parallel to one of the rx antenna. Three times, when straight out in front of me with the TX antenna pointed down as per instructions, control was lost momentarily.

I've flown the setup several times since the upgrade install with no problems... but today had three short control failures on my second flight. Noting that the first two happened very closely together straight out in front and that when getting the plane down, there was no problem and a range check when down showed no problem, I went back up and again put the plane in the same position in front of me and suffered the third short loss of control. After landing right away, the wing was pulled and the wing harness was found to be right against and parallel to one of the antennas. It is quite likely that the large harness shaded the antenna as all three control failures happened going from left to right, which could have placed the harness between the tx and rx antenna.

In all three episodes, the plane failed to respond to a new control input rather than suffering a glitch. The longest of the three lasted about two seconds.

I've flown most of the planes that have been upgraded and this is the first issue and adjustments will be made to the wing harness and antenna positioning will be carefully scrutinized. The other antenna was taped in place with plastic tape and that may also be a no-no and will get changed.
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Old Mar 17, 2013, 06:52 PM
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What receiver were you using? That would provide some more insight.

In case you didn't know, the receivers with a separate telemetry module also acts as a third receiver allowing you to cover 3 axis of orientation if you would like.

Also, you may find it useful to know that I and others have found that the transmitter antenna pointed left or right seems to allow for longer range in receiving the telemetry if you are using short range telemetry. This may imply you will also get better reception at the receiver with the antenna sideways. Regardless, I fly gliders and sometimes hold my transmitter in front of my face to block the sun in which case the antenna would point directly at the model--this is well known as suboptimal and is easily proven using a range test.

-Randy
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Old Mar 17, 2013, 07:06 PM
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BTW, it sounds like you might not have failsafes set up. You might want to consider doing / checking that for safety reasons, especially for your motor/engine.

Also, how far out was your plane? If it was close in, the antenna placement is a bit more forgiving...unless you are pointing your transmitter antenna at the model.

-Randy
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Old Mar 17, 2013, 08:45 PM
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In that plane is a RG-831B 8ch. I've been pointing the antenna 45 down as per instructions, but a friend that came over after I noted issues, encouraged canting it sideways a bit. That was before going back up after the range check and suffering a third short loss... perhaps the longest of the three at probably no more than two seconds.

What I did find was that failsafe was not engaged on the throttle, which was an oversight on my part as I had a check list sheet for the upgrades of both DMSS receivers and LiFe batteries. On the list was a column for checking the CG, the throttle kill, and the throttle fail safe. When home, I discovered that evidently I'd made up the check list for the many planes that were upgraded sometime after the first upgrade, and the Ultra Stick Lite failed to be on the list and didn't get checked for the failsafe. The rest of the fleet were on the list and all were checked off.

I recall commenting to my friend that I'd not noted any throttle cut and after landing to do the range check, took note that it had not been set and did so before going back up and experiencing the third loss of control and but no throttle cut. In that instance I was in a tight loop and when coming out the bottom gave neutral stick and the plane continued the tight loop reaching 2/3 to the top before control recovered.

After pulling the wing and perplexed as to why fail safe hadn't engaged in that instance, it was tested by turning off transmitter... and I noted that it takes a couple of seconds after signal is lost to engage but recovery of signal with transmitter turned back on is very quick, so it is possible that signal wasn't lost long enough in the third instance for fail safe to engage. All three losses were very brief.

I haven't made the planned changes to the installation yet but will report after doing so and flying the plane again.

I've an estimated fifty flights with the Jr XG8 since getting it and that flight was the only noted loss of signal from any of the several planes flown since the upgrades. As noted above, the USL had flown previously on two occasions with no issues.

Randy, I didn't know about the third receiver... I figured the telemetry antenna to be a tx antenna back to the transmitter while your saying I guess that it is a duplex antenna.
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Old Mar 17, 2013, 10:13 PM
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Quote:
Originally Posted by AA5BY View Post
After pulling the wing and perplexed as to why fail safe hadn't engaged in that instance, it was tested by turning off transmitter... and I noted that it takes a couple of seconds after signal is lost to engage but recovery of signal with transmitter turned back on is very
The transmitter actually continues sending a signal for a couple seconds after you flick the switch to the off position. Watch the blue light at the top of the transmitter to tell when the XG8 is transmitting. The timing of the light turning on and off is exactly as you describe, so I don't think there is likely to be a perceivable delay from the point of actual signal loss.

Given you are not flying at long range, the fact you have three antennas (assuming the others are setup correctly) and three independent receivers, and they are powered directly with a LiFE battery, blocking one antenna shouldn't cause this problem in my opinion.

Have you checked that you don't have an intermittent electrical connection somewhere? You might consider getting an XPS TattleTale... http://www.xtremepowersystems.net/products.php?cat=23.

Just in case there is something wrong with your receiver, you might try swapping it out with another one and putting this receiver into a plane you don't care about crashing. But, I tend be very conservative. For some reason, losing a plane to pilot error is less painful than faulty equipment for me.

Good luck!

-Randy
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Old Mar 18, 2013, 05:20 AM
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Randy... thanks for the information.

After my last post, I verified how long the fail safe took to act and noted the same thing you relate about the TX not shutting down immediately after turning off switch. Considering when the light goes out, the fail safe acts rather quickly.

The clues (lack of response and the holding of an input and failure of fail safe to act after it was set) seem to point to an interruption of power and only one flight battery (2100 mah) and switch was afforded this plane so there was/is no power redundancy. I'll likely add another switch and change to two 1300 mah packs.

I've ordered the tattletale and do have another RX and will install the current RX in an old Quickie 500 test bed and give it a few flights. I've also an opto kill switch available to install though I'm not certain I like an engine to die... preferring low throttle by fail safe.

I share your conservative nature regarding loss of planes due to electro - mechanical failure and can remember only losing one plane in forty years for such causes (a battery solder tab broke). There have been failures but none fatal and some that would have been fatal had they manifested while flying.
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Old Mar 23, 2013, 09:36 AM
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Received the Tattletale and found it doesn't report a failsafe occurrence or a receiver reboot if signal was lost when using a DMSS receiver.
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Old Apr 28, 2013, 10:21 PM
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telemtry sound levels

I've run onto my one dislike so far. A group of us are messing with some glider competition and I'm handling the piggy back launch chores and am using altitude telemetry to provide an equal release height for competitors and the beep is too low a volume to hear. I can't find a way to change the audio level on the telemetry signals.
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Old Jul 12, 2013, 05:28 AM
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XG8 Altitude Sensor TLS1-ALT

Altitude Sensor Question
I just picked up one of these. Impressive size and 2m accuracy.

The XG8 displays RX voltage clearly on the home screen so is there a way to display the Altitude on the TX Main Screen as well ?

I can only see it if I go to the 2nd screen.

I assume I can't "log data" for retrieval later? Am I right?

I used to have a Zlog until it decided to just not work any more after prolonged shelf time and I miss the ability to gauge altitude so this might do the job.

Chris.
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Old Jul 12, 2013, 06:19 AM
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2nd screen only, no logging. The radio does record maximum altitude which is easily viewed and reset from the second screen. You can also set altitude alarms which can be activated and deactivated by physical and logical switches.

The telemetry is pretty basic....essentially the features a typical user would use on a regular basis. I use mine for DLG launch height determination and for practicing altitude-limited soaring. I appreciate that the sensor is small and light.

-Randy
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Old Jul 12, 2013, 08:23 AM
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Hi Randy,
Good man.
I'll test it out tomorrow if it doesn't rain.
Chris.
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Old Jul 15, 2013, 04:02 AM
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JR Propo and Unilog2

Hello Chris,


Why not buying this unilog2?

http://www.sm-modellbau.de/shop/

All in German, but manual in English:

http://www.f5b.co.uk/CMS/data/_uploa...%20english.pdf

For Eur 99 you get altitude, vario and Logging.

I have tried it, and it works without a problem. The unilog does not recognise JR automatically, and you have to set it manually. Takes about 3 minutes.
JR hasn't been able to bring out their vario after 3 years and with this devise I was able to test it.

Jan
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Old Jul 15, 2013, 04:46 AM
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xg8 transmitter antenna position

Hello XG8 owners,

After flying with the XG8 for 2 years now I had this weekend a little surprise:

For the first time I set my failsave ( yes too lazy or no problem felt so far ..)

Flying in line away from me, distance and height about 200 mtr - supra-pro carbon, I got failsave when antenna is in the recommended position according the manual (see p. 10 manual XG11): so in line with the plane, antenna at the first about 30 degrees bend position downwards. I was able to reproduce this a couple of times.

The problem was solved when bending the tx-antenna in the not recomended position to the left/right. Actually antenna position like all the other manufacturers.

Question, what is your experience in flying glider models?

Second: I was a little disappointed with the time it took to get into failsave position, about 4 sec. after switching off the transmitter. For f3j not a big problem, but for faster models not usable.

And to make it complete: when using flight positions with delay, I am convinced that the delay is not working for trim in the rudder and elevator. Or am I wrong? Maybe it is in the recent bug-fix?

Thx for your experiences! And yes, I am an amateur in finding out after one year flying that I have a transition problem. Thought I got rusty after 4 years not flying

Jan
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Old Jul 15, 2013, 05:02 AM
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Unilog2 works with JRXG8 / JR DMSS Telemetry

Hi Jan,

Thanks for the info on the Unilog2, it looks very useful.



As for XG8 reception, I run my TX aerial drooped down and have had zero issues in both a full-carbon X1 3.5 and X2 3.8 ST (kevlar nose).
In both gliders the RX antenna is run along fuz bottom and 90 degrees to that vertically near front servo.

The Supra Pro has a carbon canopy, would that explain it?

Chris.
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Old Jul 15, 2013, 06:42 AM
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Hello Chris,

Thanks for your reply.
Today I tested with SuperStarlight, no carbon canopy/ 2.4 friendly fuse.
Same problem, explains a lot to me

I think the problem is that I am holding the transmitter to my chest, and in that case the antenna tip is pointing towards the plane. In the picture on p.10 the tx is "hold" flat like a tray tx.

Receivers build in as advised, and indeed, the supra has a shielding canopy. But as the plane is flying in a straight line away from me, that antenna won't be receiving anyway. The antenna laying straight on the bottom of the fuse should do the job.

But happy to read that only I experienced this problem, so to be solved.

Jan
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