Out with the old….

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25 September 2013 at 19:45 #43949
Paul75
Participant
@paul75
Hello Everyone.

I've recently re-wired the electrics and re-connected the R/C kit on my 1/128th HMS Duke of York and everything seems to have mind of it's own, which I understand is quite a common problem.

She runs off 2x 6v 14Ah SLA batteries with 4 geared (pulley drive) 540 motors fed by 2 electronize Type 43HX ESCs. The R/C kit is a 7 channel 40MHz Digifleet XP/FM Tx/Rx system (which includes a stand alone receiver battery) mated to a Digifleet FPS-17 servo for the rudder.

I know that this kit is now very old and I understand that it was known to be temperamental but, in the interests of economy, I was hoping that it might still give reliable service and I wouldn't need to replace it.

I will persevere to sort out the gremlins with this set up for a little longer but, bearing in mind that I won't use the model on the water if I'm not fully confident that I'm in full control of her, I may have to admit defeat and replace the kit with newer, more reliable equipment.

With this in mind, could anyone please suggest the most reliable specific systems to replace it?

I'll need:

– 7 channel transmitter and receiver kit (2.4GHz?) (is it still possible/advisable to have a separate receiver battery?)

– 2x ESCs (mtronik Viper Marine 40?)

– 1x rotary servo for the rudder

I'd like the kit to be very resistant to RFI. I understand the recent models have microprocessors installed to counteract this.

If possible, I'd also like the receiver, ESCs and servo to be water resistant by design.

Sorry that this is a hefty post but if I replace the control kit I'd like to get it right first time so your advice will be very much appreciated.

Mant thanks,

Paul.
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25 September 2013 at 19:45 #5262
Paul75
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@paul75
25 September 2013 at 22:52 #43952
Charles Oates
Participant
@charlesoates31738
Hi Paul, I have the same Fleet gear, it was and is utterly reliable, exept for one time. The transmiter batteries got old and were short of volts even when fully charged. The result was glitchy operation, it had a mind of its own. It,s worth checking these first, an easy and cheap fix. Under volt receiver batteries have a simmilar effect.

Regards,
Charlie.
26 September 2013 at 08:49 #43957
Paul75
Participant
@paul75
Thanks for your reply Charlie. I will persevere with the Digifleet kit and will take advice from others with far more experience than I have but I am loathe to spend time and money trying to improve its performance when there are affordable newer replacements. It's more than likely that the problem is really down to my inexperience – hopefully with guidance the situation will improve such that my kit is as reliable as yours.

All the best,

Paul.
26 September 2013 at 09:37 #43959
Dave Milbourn
Participant
@davemilbourn48782
Paul
I would advise replacing the receiver and transmitter packs as a matter of course, along with all wiring between them and the circuit boards which they power. This is because stranded copper wiring – particularly that connected to negative battery terminals – can corrode over time and turns black. You can check by making a small slit in the black PVC insulation close to a join and peeling it back to reveal the conductors underneath, Also remember that Fleet plugs are centre = negative while practically everything else on the market is centre = positive.
Component Shop can supply just about any size, shape and capacity of NiMH pack which you might require. The new packs will have much greater capacity than the old Fleet ones (which are probably NiCads) and thus need longer charging times.
Ref your wish list, be careful buying so-called 7 channel radios. You may find that you only have four proportional channels and that the others are simple 2-way On/Off channels; these are only good for switching single circuits.
MTroniks 40A ESCs are waterproof, but they are expensive and somewhat crude c/w Microgyros' FR40.
Some servos are water-resistant but few are genuinely waterproof, while I have never encountered a receiver which is waterproof (how do you waterproof connecting pins and sockets?). If you mount your receiver and servos away from any "wet" areas of the boat (e.g. the bilges) then you should have no problem. If you do then I would suggest that the electronics is the least of your worries – because your model is probably sinking!
Dave M

BTW Do make sure that the motors carry a full complement of suppressor capacitors. That's 0.01 uF ceramic capacitors between each of the motor terminals and the motor can, and a 0.1uF ceramic one across the two motor terminals.

Edited By Dave Milbourn on 26/09/2013 09:40:52
26 September 2013 at 15:00 #43965
ARTHUR COLLETT
Participant
@arthurcollett48040
Hi Dave

I see you recommend 0.01uF for 6 volt. what would your rcomendation be for a 12V operating system. Motor simular or same( marking sticker removed) to Graupner BB 900.

Thanks al lot

Arthur
26 September 2013 at 15:16 #43967
Dave Milbourn
Participant
@davemilbourn48782
Voltage and value is not critical as long as you use ceramic caps which are at least the rating of the battery (in my experience even the little ones are 100v). You may find tiny little 0.01uF caps a bit fiddly around a big 900 case, so use larger values if you like. I fit 250v 0.1uF and 0.22uF to 900 motors. For a full treatise on motor suppression have a read of this **LINK** (by David Harrison of Model Sounds Inc, Canada)

Dave M

Edited By Dave Milbourn on 26/09/2013 15:17:36
27 September 2013 at 08:00 #44002
ARTHUR COLLETT
Participant
@arthurcollett48040
Thank Dave for the most interesting link and the info regarding the caps. your help most surely appreciated.

Arthur
28 September 2013 at 11:20 #44050
Paul75
Participant
@paul75
Hello Everyone.

Many thanks for your replies. I think the transmitter and receiver batteries seem to be OK, so first I'll fit capacitors to the motors (3 out of the 4 motors have them fitted across the terminals already but I'll replace these) and use ferrite rings on the leads between the receiver and the ESCs and servo.

Regarding possible replacement Tx/Rx kit, can anyone recommend the Planet 7 channel 2.4GHz kit?

Thanks again,

Paul.
28 September 2013 at 11:30 #44052
Dave Milbourn
Participant
@davemilbourn48782
It's only suitable for a range up to 100 metres. That said, it has two useful extra channels with a 3-way switch and rotary knob respectively. The Planet T5 is a decent budget set and there's no reason why the T7 shouldn't also be – with the caveat about the range.
DM
28 September 2013 at 23:44 #44078
Paul75
Participant
@paul75
Thanks Dave.

The 2.4GHz radio kits are appealing c/w the older 40MHz sets because of the immunity to RFI. The Planet T7 combo sets are very keenly priced so I'll have to make a balanced judgement regarding how much time/money to invest in tinkering with the old Digifleet set when it may be far easier to simply update with a new set. I've just bought the capacitors and ferrite though so I'll see how things go in the short term.

Thanks again for all your advice,

Paul.
30 September 2013 at 16:36 #44109
Paul75
Participant
@paul75
Hello Everyone.

I think I'll eliminate the Planet T7 kit from my "wish list" due to the limited range of the system (thanks for the info Dave).

Can anyone tell me whether or not the Radio Link 2.4GHz 7 channel system is any good? Again, it's very cheap and apparently has a ground range of 350m which I think should be sufficient for model boating.

The next step up would appear to be Hitec or Spektrum systems which sell for about £200 for Tx/Rx combos, so is it a case that you get what you pay for?

Many thanks,

Paul.
19 October 2013 at 21:26 #44495
Paul75
Participant
@paul75
Hello Everyone.

I've now replaced the batteries in the old Digifleet Tx/Rx system but now the kit doesn't seem to exert any real control at all. I think I may have previously mistakenly fried the receiver by incorrectly reconnecting the leads (receiver to ESC).

I have persevered as best I can with the old kit but, since I want to make tangible progress with the model, I have now decided to comprehensively modernise the control systems.

Therefore, I have come up with the following "wish list":

1) Futaba Field Force 7 2.4GHz 7 channel Tx/Rx

2) Futaba S3306 MG heavy duty water protected servo (for the rudder)

3) Two Microgyros FR40 ESCs

4) Actions Electronics' P102 Power Distribution Board fed by a P103 Parallel Power Board

Does this sound about right? Your thoughts would be much appreciated.

Many thanks,

Paul.
20 October 2013 at 20:17 #44506
Malcolm Frary
Participant
@malcolmfrary95515
A friend has a 1/144 DoY, it is quite happy with its very standard servo. Mind, it is in an area where flooding is not likely, even in heavy weather, which it has experienced, and been untroubled by. So paying the extra for water resisting is of dubious value, but is a valid personal choice.

I have a 1 metre yacht – the rudder on that probably creates many times the strain that will ever happen on a 1/128 scale warship. The standard servo copes perfectly adequately, even sculling the yacht in on occasion. Again paying the extra is a personal choice. But realize that the extra load demanded by a heavy duty servo will require a heavier duty power supply if the original problem of items twitching is to be avoided. This includes ALL of the wiring. Many modelers think that the black wire is somehow optional. It isn't. All of the thick, heavy bits demand to be at least as good as the red bits, not least because other black wires can provide a poor quality path, creating false signals , erratic behaviour and a feeling for the need for new equipment.

Can't comment on the particular ESCs, as I have not yet used any.

Actions products can be implicitly relied on if the instructions are read, understood and, importantly, followed.
21 October 2013 at 20:26 #44535
Paul75
Participant
@paul75
Thanks for your reply Malcolm. I agree that the heavy duty / water resistant servo is most probably overkill but wish to ensure long-lived reliability and this model is specced as being robust. The reliabilty of the model is a top priority, especially considering its size, so I'll certainly be looking to use good quality components as you advise.

Thanks again,

Paul.
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