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Returnee to EF seeking advice

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Stephen Belshaw06/11/2018 07:45:57
76 forum posts
14 photos

I was a regular flyer around thirty years ago, mainly slope soaring but graduated to electric flight as the hobby first started to establish itself. Other aspects of my life took over and I fell out of the habit, but retained most of my airframes and electronics. I am now wanting to re-start the hobby and would like to utilise what I have wherever possible. I understand that things have moved on a lot since I last flew so would like some advice on what I can hope to achieve.

First off, my transmitter set-up looks to be outmoded, I have a JRX347, which of course is 35Mghz, on firing it up I discovered that it is not responding with control surfaces juddering and no answer to my control commands. I therefore intend to replace this, probably with a Hitec Flash7 combo as I have a fair few Hitec and JR micro servos that I'm guessing I could still utilise. Another option, in light of Hitec abandoning Tx upgrades would be FrSky Tarans Q X7 although the set-up and programmming looks a little daunting.

The bigger issues though surround my airframes and the batteries/motors and ESC's that I have. It seems Ni-Cads are now out of fashion!

Airframe No.1 is a Graupner Cherry ii which I flew extensively before my sabbatical from the hobby. I would like to get this airborne again as my first step to flying rehab. It's powered by a Graupner Speed 700 BB Turbo (I think) 9.6V through a "Mini Switch 40" speed controller and 10 cell NiCad pack. Ideally I would like to keep everything in the airframe and just swap out the battery pack for the latest tech.

Airframe No. 2 is a Multiplex TwinStar, also extensively flown, powered by 7 cells and has a Picos micro Rx/ESC. Again, ideally just swap the battery pack.

Airframe No. 3 is a part built Graupner Match which I would like to complete and get airborne. The motor is a Graupner Speed 500 BB Race VS, ESC 7.2V, ESC is a Jeti JES 350 Eco - this is marked "6 - 12 cells NiCd" but can I assume any type of battery would be ok with it?

To summarise, it seems I need to upgrade my radio gear, replace obsolete NiCad's with newer battery technology and acquire a suitable charger for these (would prefer an AC/DC dual charger). I'm hoping I can utilise my existing ESC's and servos so advice on which is the best way forward along with kit recommendations would be greatly appreciated.

Frank Skilbeck06/11/2018 08:09:54
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4423 forum posts
101 photos

Stephen, yes you can use all your existing servos and ESCs with 2.4 receivers with any modern brand, so no issues with using Frsky receivers, just note with Frsky that they have a couple of transmission protocols, one with is EU compliant and one used in the US and other places, if you buy all you kit from EU suppliers then no issue, if you say buy receivers from Hong Kong then they may come with the "wrong" firmware, you can change it but something to be aware of.

As regards batteries yes you can use Lipos instead of Nicds, just a couple of points to be aware of

1) they are much lighter

2) your ESC low voltage cut out will not be set for Lipo and if you fly to too low a voltage then you will damage the Lipo (note you can now use telemetry to monitor the voltage, current, mah etc)

3) the lipos will hold their voltage much better under load so don't be tempted to go for a higher voltage than the Nicd packs or you may burn out the brushed motors (yes I've done this)

Lots of good chargers out there, I'm using a couple from Overlander that I am very pleased with.

Edited By Frank Skilbeck on 06/11/2018 08:11:28

Denis Watkins06/11/2018 08:25:53
3743 forum posts
179 photos

Your JR 347 Stephen

I seem to remember that they had a Lithium internal battery on the PCB, that lasted about 5 years ?

Must be flat by now

But was a good Tx and would still be useful, though 2.4 gig is the way to go

Edited By Denis Watkins on 06/11/2018 08:26:46

Stephen Belshaw06/11/2018 09:35:08
76 forum posts
14 photos

Many thanks for the prompt replies.

Frank, Point noted on not going overboard on the voltage - I may have been tempted! Good to know I can use my existing ESC's, what would be the minimum voltage for the LiPo batteries and would a 2000mAh LiPo give me the same flight time as a 2000mAh NiCd?

Denis, yes I read about the lithium battery but as I am still getting a readout on the screen and can scroll through the functions I assumed it was still ok. I've seen a tutorial for changing the lithium battery but it looked quite involved and the fact it's going to go at some point steered me towards replacing the whole thing. Shame really as I liked the 347, do the symptoms I'm experiencing indicate any particular problem or do I just assume it's goosed and give up on it?

Engine Doctor06/11/2018 09:36:56
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2254 forum posts
24 photos

Re your JR X347 . If its OK after a battey Change including the lithium button cell in the PCB, then it can be converted to 2.4 by replacing the module with an FrSky module . Siply replaces the old module . Available from Rapid RC and RC Life cost about £35 .

Denis Watkins06/11/2018 10:20:08
3743 forum posts
179 photos

More investigation is needed Stephen

Juddering etc can easily be your Rx, or your Rx connections, and low power

Low power sends servos juddering

Not entirely your transmitter to blame

Clean up contacts, I mean 30 years is a good layoff

jrman06/11/2018 12:10:33
343 forum posts
3 photos

Re the 347. Didn't that model of Tx require the sticks to be calibrated if the main battery was left to discharge completely? The calibration method was detailed in the manual and was very easy to do. The pc board lithium button cell retained all settings including calibration. It's worth a call to Mike Ridley at Model Radio Workshop (07708 0436163). If he can't help, nobody can!

 

Edited By jrman on 06/11/2018 12:14:39

Dave Hess06/11/2018 13:22:12
301 forum posts
18 photos

If you're happy with your transmitter, you can upgrade it to 2.4 gHz with a 4in1 module:

**LINK**

The 4in1 module works with just about any receiver rather than restricting you to a single protocol. I use the JP4in1, which works perfectly with Frsky and DSM2/DSMX receivers, including the Orange R610 V2 that only costs £4.50!

Frank Skilbeck06/11/2018 13:49:05
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4423 forum posts
101 photos
Posted by Stephen Belshaw on 06/11/2018 09:35:08:

Many thanks for the prompt replies.

Frank, Point noted on not going overboard on the voltage - I may have been tempted! Good to know I can use my existing ESC's, what would be the minimum voltage for the LiPo batteries and would a 2000mAh LiPo give me the same flight time as a 2000mAh NiCd?

If the resting volts drop below 3.0v per cell it's effectively flat, the volts under load will depend on the current being drawn, you can buy battery checkers which tell you the % capacity left as the lipo resting voltage is directly releated to the remaining capacity. So if you are not using onboard telemetry readings then it's best not to fly to less than 30% capacity. Yes you should get longer from a Lipo for two reasons, firstly they are lighter and 2nd they hold their voltage better under load, so in both instances this means you'll be flying at a lower throttle setting or climbing to height much quicker, of course if you fly at 100% throttle all the time then this doesn't apply.

Stephen Belshaw06/11/2018 17:23:03
76 forum posts
14 photos

Well I've had another tinker with the 347 and can't get anything out of it, when I switch the Rx battery on I get the usual servo noise but the Tx won't move anything. My Rx battery checker tells me power isn't an issue.

JRMan, I've looked through the manual and cannot find any reference to re-calibration.

Whilst it may be fixable by Mike Ridley, as suggested above, given the relatively low cost of new gear I can't see a repair being cost effective.

So, I'm now edging towards buying a new Tx/Rx combo with in-built telemetry (so I can keep an eye on the LiPo voltage), new 2S and 3S power packs and a suitable charger. I'd like to source all of these from one supplier to simplify the logistics as I'm in Hungary.

I'm considering the FrSky Taranis Q X7 with matching Rx but perhaps a bit daunted by the potential difficulty of programming it, anyone got experience of this system or can recommend alternatives?

Martin Harris06/11/2018 18:32:09
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8672 forum posts
214 photos

It might be worth removing and reseating the transmitter crystal in case the contacts have oxidised over the decades.

Dave Hess06/11/2018 18:40:59
301 forum posts
18 photos
Posted by Stephen Belshaw on 06/11/2018 17:23:03:

I'm considering the FrSky Taranis Q X7 with matching Rx but perhaps a bit daunted by the potential difficulty of programming it, anyone got experience of this system or can recommend alternatives?

I have a lot of experience as I changed over to modern systems a few months back. The Taranis uses Open Tx. It's not something that you can learn from the rather massive manual. Instead, you have to watch Youtube videos, which show you how to do each task you want, then, when you can't figure out what the guy is doing, you have to ask on forums. After some time, you figure out the basics, but it will take longer if you want to do anything complicated, like mixing, telemetry and stabilisation. If you stick with it, everything gradually falls into place until you end up with a system that's more versatile than many others.

If you're not good at hooking things up to PCs and doing complicated settings, Open Tx might not be the best choice. I had the advantage of being an IT and electronics teacher for ten years. Only you can judge whether you think you have the capability. The problem is that everything is easy when you knw how, so now, basic settings look dead simple and logical to me, but there was a bit of work to get to that position.

It's not just Frsky that uses Open Tx. There are more and more brands starting to use it. Have a look at the really nice Flysky Nirvana N14 that not only uses Open Tx, but it has a version of the Open Tx Companion in it, so that you can do everything through the LCD in a more user-friendly way rather than having to do it through a PC. There were a couple of teething problems that showed up on the review models, but I think they've been solved for the main production. If not, they soon will be. I'm pretty sure that my next transmitter will be one of those. I love the design and the way everything is protected. My First Taranis had two broken switches on delivery, so had to go back. Now the replacement has already had two more. That's despite it being handled carefully and always kept in its case. the switches are so fragile that they can be broken while in the protective case!

PatMc07/11/2018 00:01:31
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4169 forum posts
520 photos
Posted by Stephen Belshaw on 06/11/2018 17:23:03:

Well I've had another tinker with the 347 and can't get anything out of it, when I switch the Rx battery on I get the usual servo noise but the Tx won't move anything. My Rx battery checker tells me power isn't an issue.

JRMan, I've looked through the manual and cannot find any reference to re-calibration.

Whilst it may be fixable by Mike Ridley, as suggested above, given the relatively low cost of new gear I can't see a repair being cost effective.

So, I'm now edging towards buying a new Tx/Rx combo with in-built telemetry (so I can keep an eye on the LiPo voltage), new 2S and 3S power packs and a suitable charger. I'd like to source all of these from one supplier to simplify the logistics as I'm in Hungary.

I'm considering the FrSky Taranis Q X7 with matching Rx but perhaps a bit daunted by the potential difficulty of programming it, anyone got experience of this system or can recommend alternatives?

Stephen, I may be just stating the obvious that you've already considered but IIRC the JR 347 has PCM & PPM capability also some JR tx's have two versions of PCM.
Is it worth checking that your Tx & Rx are on matching modulation systems ?

Re the Taranis - I don't think that the QX7 is the best choice for electric gliders as it doesn't have any sliders. Operating spoilers/spoilerons or flaps would have to be done using either a switch or rotary knob.
OTOH the Taranis X9D does have sliders, which means any of these landing aids can be operated with both hands still on the sticks.
My first dedicated 2.4GHz Tx was a Taranis X9D which was from the first batch to be imported into the UK. It followed on from 35MHz Futaba FF7, FF8 & a Multiplex Cockpit SX that I converted to 2.4 MHz using FrSky module. Although I have chosen to upgrade the Taranis in various ways using genuine FrSky parts which have always been very reasonably priced I have never suffered a failure of any switch or other item.

IMO the programming difficulties have been overstated, in fact I find it easier than any of the other 3 Tx's I've mentioned.


Mike Blandford07/11/2018 00:50:45
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514 forum posts
22 photos

You aren't restricted to openTx on most FrSky radios (and some others as well), you also have the option of ersky9x firmware.

As an example, here is the menu index display (from a FrSky QX7) you get when editing a model. The menus are, in my opinion, easier to follow and find settings than in openTx.

sd1.jpg

BTW PatMc, my QX7 does have a slider. I added one, and used one of the coloured LED outputs for the switch as the extra analog input. A slider is far more use than three colours for the power switch LED.

Mike

Allan Bennett07/11/2018 06:29:52
1523 forum posts
38 photos

Posted by PatMc on 07/11/2018 00:01:31:

Posted by Stephen Belshaw on 06/11/2018 17:23:03:

..... I'm considering the FrSky Taranis Q X7 with matching Rx but perhaps a bit daunted by the potential difficulty of programming it, anyone got experience of this system or can recommend alternatives?

..... IMO the programming difficulties have been overstated, in fact I find it easier than any of the other 3 Tx's I've mentioned.

I agree about the proramming of OpenTX: I find it much easier than the pre-programmed options in my Futaba, for I only need to know what I want each individual channel to do in response to individual stick inputs, rather than having to figure if 'ailevators' or 'elevons' or something else is the mix I'm looking for.

I must admit I haven't really got my head around programming on the Tx screen, but connecting to a PC and using OpenTX Companion makes the process a real doddle.

One feature I find a real boon is the ability (as with some other brands these days) to add customised voice announcements to the switches so that before a flight a quick flick of the switches will remind me what each one does for that particular model.

Stephen Belshaw07/11/2018 07:44:40
76 forum posts
14 photos

PatMc, stating the obvious is a good thing as I may well have missed something very obvious! The screen on my Tx tells me I am running in "C" mode, I assume my receivers are the same, how do I check - is it marked on them?

I've had a look at some videos and written guides for the OpenTx software and I thought it was very logical and something I'd feel happy getting to grips with, as much as I liked my 347 I always found getting about the menu clunky so I'm happy to run with it. I gather that the programming can be done through the Tx or via a computer with the computer option (Mac in my case) apparently quicker and simpler, as Allan corroborates above.

Very good point on the lack of sliders, I think that rules out the QX7 (not wishing to do any DIY moods) as I would want the option to incorporate flaps/spoilerons/CROW braking.

As always with these things the more one learns the more the desirable options moves the budget inexorably upwards. I'd set a self imposed budget of under £150 for a Tx/Rx combo with a minimum 7 channels and telemetry, it now looks like that's under pressure!

 

Edited By Stephen Belshaw on 07/11/2018 07:47:15

Allan Bennett07/11/2018 09:45:05
1523 forum posts
38 photos

If you're looking at FrSky, I think the standard X9D is the one to go for. It has all the switches, sliders, and knobs you'll need, and can handle 16 channels with the appropriate receiver.

PatMc07/11/2018 15:36:19
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4169 forum posts
520 photos
Posted by Stephen Belshaw on 07/11/2018 07:44:40:

PatMc, stating the obvious is a good thing as I may well have missed something very obvious! The screen on my Tx tells me I am running in "C" mode, I assume my receivers are the same, how do I check - is it marked on them?

Stephen, I've never owned a JR set but I came across this from the X347 manual via google ...

image1.jpg

...so it appears your Tx is on PCM mode.

I'd guess that any PCM Rx will have "PCM" clearly marked on it but even if it hasn't you have nothing to lose by changing the Tx mode to PPM & trying that.
If there's still a problem check if the Rx is "dual conversion" or "single conversion" & that it has the correct type of Xtl fitted.

Stephen Belshaw07/11/2018 15:46:10
76 forum posts
14 photos

Well I finally bit the bullet!

After what seemed an age trawling the internet I finally settled on HobbyKing as a one-stop shop for everything I needed and have ordered a Taranis X9D Tx/Rx combo, some 2S and 3S LiPo packs and an AC/DC charger. All for £270 so cannot really complain as it should be enough to re-launch my flying "career".

Could be up to 10 days before it arrives so I have some time to explore the OpenTx software and maybe advance the build on my part finished "Match".

Thanks for all the help in nudging me towards what will hopefully prove to be the right decision.

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