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Author Topic: Radiolink - T4U Review  (Read 21936 times)

dodgy geezer

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Radiolink - T4U Review
« on: December 03, 2010, 02:30:05 pm »

Radiolink T4U - http://www.radiolink.com.cn/doce/product-detail-42.html - http://www.giantcod.co.uk/gianitcod-24ghz-4channel-mode2-transmitter-p-403779.html



While looking for cheap imported brushless motors I came across the RadioLink T4U 2.4Ghz radio for sale on the Giant Cod website, who, I think, are the sole UK importer. At a price of £25 it seemed too good to be true, but the comments on the associated forum were uniformly good, and I bought one to see what this new frequency might offer...


What you get

The radio comes as a Tx/Rx combo. Extra receivers are very cheap (£9) and I bought two at the same time, as well as a selection of cheap Giant Cod miniature servos (£1.99 each, though now at £2.23!). All this arrived within a few days in a well-packed parcel.

The TX/Rx combo came in a simple white cardboard box, with no internal packing or advertising material. There were no instructions included, and presentation had obviously been sacrificed with the aim of keeping prices down. This really is a rock-bottom cost unit!


Tx

First impressions of the Transmitter were mixed. The unit is quite large, around 7 1/2" square not counting the aerial, is made of thick black plastic and has a satisfying solid feel. But the trim is cheap aluminium printed strip, with a blanked-off hole for exchangable crystals (not needed on a 2.4Ghz set), and a primitive row of four slots cut in it through which you can use a screwdiver to alter the servo-reversing switches on the internal PCB. The stick gimbals (adjustable length) were of good quality, smooth and strong, and the mechanical trims had a soft, quality feel to them. The On/Off switch cover had come off in the box (easily replaced), and I had to open the Tx case to loosen the aerial screw to allow it to be centered from its sideways transit position.

The system is advertised as a simple 4-channel radio with no features. Apart from the pair of stick gimbals, the front of the radio has a Power switch, a very solid boss for attaching a strap, and a red led light. This glows when power is on, and (according to the forum) blinks when the voltage is low, though I have not tested this.

On the side of the Tx there is a charging socket (no charger is included), and on the back is a 'Trainer' socket (not functional), and a battery cover for 8 AA cells. It will work with Ni-Cad/Ni-Mh or alkalines.

Rx

The receiver is a small hard plastic case with a single-deck PCB inside, though this has a daughter board attached to the top to provide an aerial circuit. The Rx is about 1 3/4" x 1" x 1/2", and has outputs for 6 servos, plus another marked '7/Batt'. There is only one aerial, and a single small binding button. The version I have has the connectors mounted vertically in the case - they can also be bought with a horizontal mount varient. Binding is very simple - just turn on the Tx, turn on the Rx and press the Rx button. A green flashing light from the receiver tells you that binding has been successful. The forum warns people that trying to bind close to a computer wireless connection which is also transmitting at 2.4Ghz may cause problems, but I had no difficulty with one about 12 feet away...


Operation

I have found the set to be very reliable in practice, and easily equivalent to my other more costly sets. It has no computer set-up or model setting memory, so I suppose it should be compared to the simple 27Mhz systems on sale, though the sophistication of a 2.4Ghz makes for a much easier operating experience, especially at a crowded pool.

Given that there were no instructions of any kind included with the set, I went to the Giant Cod forum to gather more information about it. This produced some surprises.

The first is that the Tx has two undocumented switches on the internal PCB. There is a 'Mode' switch, allowing easy change between Mode 1 and Mode 2. There is also a 'Mixer' switch, which allows channels 1 and 2 (Aileron/Elevator) to be run either seperately or mixed.

The second is that, though the set is advertised as 4-channel, the internal circuitry for 6 channels appears to be included. The Tx PCB has several 'spare' sockets on it which can be used to 'upgrade' the sets (though this service is not offered by the manufacturer). The Giant Cod forum has details of the circuit changes (remove a resistor and attach a switch) to give an extra switched channel, and it seems likely that another proportional channel and the trainer/simulator socket can be made operational.

There is considerable discussion of this set at Giant Cod, including a circuit for multiplexing two of the receivers to provide a high-security redundant radio link for critical applications, and details for adding rate switches to channels. Early versions of the set needed an extra resistor to be added to the sticks to allow full throw, but I understand that this has now been corrected. The 'insides' picture below shows a couple of unconnected components which I am adding to provide rate control...


Conclusions

The early versions of this set were similar to many Chinese products - inadequately documented and of variable quality. But the current sets seem to be improving, and offer excellent value for money. A manual for the set now seems to be available from here:  http://www.radiolink.com.cn/upload/2010/04/08/q3tzer6l1q1n21270694380.pdf

Even so, given the sparse nature of the back-up and information on this set, I would say it was more useful to the experienced modeller who wants a rock-bottom priced intro to 2.4 Ghz rather than a beginner who does not know how to use a radio. But it works well, and the price is hard to beat. I think that this is the cheapest 2.4Ghz set currently available from a UK distributor...












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barriew

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Re: Radiolink - T4U Review
« Reply #1 on: December 03, 2010, 06:10:48 pm »

Howes also stock this set - more expensive (£35) - but possibly with some sort of guarantee? Having said that, I buy mine from GC. I have so far had one receiver fail (out of 6) - could have been something I did - and at less than £9, (Howes £15) I'm not too bothered.

Barrie
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harinell

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Re: Radiolink - T4U Review
« Reply #2 on: December 03, 2010, 09:12:08 pm »

hello
I have bought from gaint cod 4 transmitters and 12 receivers for my self and fellow members at SMBC, all are reliable and superb value for money.
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cos918

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Re: Radiolink - T4U Review
« Reply #3 on: December 03, 2010, 10:08:21 pm »

I bought this set from Howes. 1 Tx and 2 RX. 1 did not work. Found the cause to be cheep s### Chinese solder . I brushed the excess off and now it works. I would rate it as a great 4ch kit,only down side Chinese qualty control.

John
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Netleyned

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Re: Radiolink - T4U Review
« Reply #4 on: December 04, 2010, 06:38:17 am »

According to the link supplied by DG, the pdf shows the T4U as not being 2.4GHz.

Mine is badged T4U and is is definitely 2.4GHz

As stated a bit confusing to someone new to RC boats as it is a very flyer orientated instruction sheet.

Having said that, cheap as chips, ideal for yachts with ratchet for sail winch on LH stick and rudder on RH stick.

Just ordered another one plus 4 receivers   :-)) :-))

Ned
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dodgy geezer

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Re: Radiolink - T4U Review
« Reply #5 on: December 04, 2010, 10:13:34 am »


According to the link supplied by DG, the pdf shows the T4U as not being 2.4GHz.



Addenda

1 - prices quoted in the review were 'general ball-park' and subject to change. For info, current prices at GC (which have recently gone up) are:

Tx/Rx combo - £25.65
Spare Rx       - £9.02

2 - While the majority of people enthuse about the kit, some forum members complain about poor quality control, especially poor soldering of wires. At these prices it is likely that manufacturers quality control is non-existent, or limited to a single check that the product works at the end of the assembly line. Consequently, I think it is a good idea to open up the Tx and check that the internal connecting wires are reasonably well soldered before initial use - improving where necessary. This is another argument for experienced R/C persons to buy these sets, rather than rank beginners.

3 - I have seen reports of these sets 'failing', where later the failure was traced to a faulty connected component - quite often a servo. People using these kits are likely to be using very cheap batteries, ESCs and servos as well, so reports of Tx/Rx kit failure may be exaggerated by including failures of other cheap components. My belief is that, so long as a quality control check is done by the final purchaser, these kits do not have an excessive failure rate, but that is not based on detailed examination of figures....

4 - The RadioLink company uses the same basic Tx box for all of its products, which include 4 - 6 channel, helicopter/fixed-wing, 35/40/72 Mhz and 2.4Ghz systems. Their documentation is a bit sparse. My understanding is that the 4 channel 35/40/72 Mhz set is called the T4U, and the 4-channel 2.4Ghz set is called the T4EU. Life is made confusing by the fact that sellers in the UK seem to call both sets the T4U, and the single instruction sheet seems to apply to both sets. My initial link to the radio set at the top of my review shows the T4EU, but the review refers to the set as the T4U, which is also how both the T4EUs I have are marked. RadioLink obviously do not want to spend extra money adding an 'E' to some of their trim stickers! I should really have included this explanation with the review....
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Circlip

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Re: Radiolink - T4U Review
« Reply #6 on: December 04, 2010, 11:59:49 am »

Since you've bitzed it DG, can you show a picky of the component side of the panel? Sad, yes I know, anorak thing but still interesting.

  Regards  Ian.
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dodgy geezer

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Re: Radiolink - T4U Review
« Reply #7 on: December 04, 2010, 01:22:48 pm »

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pugwash

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Re: Radiolink - T4U Review
« Reply #8 on: December 04, 2010, 01:50:19 pm »

DG - I have read this and other posts about r/c equipment and seen mention of Mode 1 and mode 2
could you please explain what they are or do. 
thanks
Geoff
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dodgy geezer

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Re: Radiolink - T4U Review
« Reply #9 on: December 04, 2010, 02:30:37 pm »

DG - I have read this and other posts about r/c equipment and seen mention of Mode 1 and mode 2

Not really applicable to a boat - it refers to the allocation of controls on the Tx box.  Do you have elevator and rudder on the left stick (mode 1) or elevator and aileron on the right stick (mode 2). Or indeed, some other combination entirely....

This is vitally important to standardise on if you are ever going to pass your transmitter to someone else - perhaps while you are learning to fly. If no one else is ever going to use your controller you can allocate controls in any way you like, though Mode 1 is common in Europe and Mode 2 in the US.

The 'standardisation' of 'modes' is an informal agreement between modellers and manufacturers, and has an interesting history - here is a url - http://www.nasa0406.org.uk/Tx%20mode%20History%201.htm

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pugwash

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Re: Radiolink - T4U Review
« Reply #10 on: December 04, 2010, 05:06:13 pm »

Thanks DG - not something I need to worry about then.
Geoff
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richald

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Re: Radiolink - T4U Review Update
« Reply #11 on: January 08, 2011, 11:23:02 am »

Received mine yesterday 7th Jan 2011 Case now marked T4EU/FHSS

No improvement in the servo reversing switches – you still have to use a torch, and poke into black hole with a screwdriver – just a thought : since
the Tx has no multi-model memories, it is possible that you may need servo reversing more often, so why make it difficult to access?

Case seems to be a little better finished – although the lower metal panel still looks a little ‘rippled’

Mine was supplied with a R7EH Rx (side mounted servo connections) – one point to note, there aren't any markings on the case to indicate
the servo cable pinouts. FYI - if you lay Rx on flat surface from the bottom the pinouts are ground, power and servo signal.

Binding button is absolutely minute and not well lined up with hole in the case – definitely a case of peek before you poke  O0

I might be teaching granny to suck eggs here, but I don't think anybody else has mentioned it. There is a
circular ‘button’ on each of the top corners of the Tx, these can be levered off very easily and will allow the proper mounting of compact toggle switches.

Internally : R11 is no longer fitted and the layout of the PCB seems to be slightly different – I will try to get a photo.

 
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dodgy geezer

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Re: Radiolink - T4U Review Update
« Reply #12 on: January 08, 2011, 12:56:37 pm »

Received mine yesterday 7th Jan 2011 Case now marked T4EU/FHSS

Radiolink have splashed out on some new stickers!


Case seems to be a little better finished – although the lower metal panel still looks a little ‘rippled’

Your pictures show it to look a little better - I think that this is the major disadvantage to the set. If they redid that thin front trim to improve the quality and added a little DIPswitch for reversing/mixing it would look a lot better...


Mine was supplied with a R7EH Rx (side mounted servo connections) – one point to note, there aren't any markings on the case to indicate the servo cable pinouts. FYI - if you lay Rx on flat surface from the bottom the pinouts are ground, power and servo signal.

The markings on the vertical connection case are hard to see - moulded in translucent plastic. Not having any (and no instructions) on the side mounted case is another reason why this set is not suitable for beginners...


I might be teaching granny to suck eggs here, but I don't think anybody else has mentioned it. There is a circular ‘button’ on each of the top corners of the Tx, these can be levered off very easily and will allow the proper mounting of compact toggle switches.

You can see the 'buttons' in the opened case picture above, but there is no attention drawn to them...



Internally : R11 is no longer fitted and the layout of the PCB seems to be slightly different – I will try to get a photo.


That would be very interesting - the GC forum would also like to see that. I am still of the opinion that an extra proportional channel is somewhere inside waiting to come out....


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dodgy geezer

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Re: Radiolink - T4U Review
« Reply #13 on: January 08, 2011, 01:59:28 pm »

P.S.

What is your opinion of the trims?

The first set I had (which I wrote the review on) had soft trims, which you could easily adjust with just a fingernail pressure, making a slight purring noise. The second set I got had harsher trims which required a bit more of a push, and made a louder click....
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barriew

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Re: Radiolink - T4U Review Update
« Reply #14 on: January 08, 2011, 03:57:39 pm »

No improvement in the servo reversing switches – you still have to use a torch, and poke into black hole with a screwdriver – just a thought : since
the Tx has no multi-model memories, it is possible that you may need servo reversing more often, so why make it difficult to access?

What I did with mine was to paint the switches white - no easier to get at, but easier to see without artificial illumination {-)

Barrie
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richald

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Re: Radiolink - T4U Review
« Reply #15 on: January 08, 2011, 05:48:31 pm »

PCB changes are very subtle and may not be significant - there seem to be a lot of changes to the component sceen print

before and after photos - I have pinched ashleylads photo of an April 2010 post on Giantcod forum and tried to match the two photos.

APRIL 2010                            JAN 2011
     

Trims are still soft - I thought about painting the ends of the levers - ditto on the servo reversers...

On the subject of adding switches and pots - I did a search of t'interweb and didn't manage to locate any suitable ones!

I moved from Sheffield about 14 months ago. There is a wonderful electronics spares shop - Bardwells on Abbeydale Road
http://www.bardwells.co.uk/default.asp which seems to stock all these 'odd' components - now a 3 hour round trip
away :(( . Anybody know of anything similar in East Yorks?

Richard

I have stripped out the joystick pots from an old 27MHz set but the cases don't have threaded collars and the
metal shafts will need cutting to length and flats filing on -  they check out as 5K resistance.


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richald

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Re: Radiolink - T4U Review
« Reply #16 on: January 08, 2011, 06:13:32 pm »

Its amazing! - After I had dug out the URL for Bardwells in my last post I went and had a closer look at their website -
up until now I didn't  know they had a web site!

they actually list suitable switches

http://www.bardwells.co.uk/detail.asp?stockid=SW014&ref=subcats.asp%3Ft%3D%26qfcode%3D%26catid%3DTOG001%26manuid%3D%26keywords%3D%26minprice%3D%26maxprice%3D

and possibly suitable pots although no mounting collar and 23mm dia may limit the number you could squeeze inside the Tx case!

http://www.bardwells.co.uk/detail.asp?stockid=SERV01&ref=subcats.asp%3Ft%3D%26qfcode%3D%26catid%3DMISP01%26manuid%3D%26keywords%3D%26minprice%3D%26maxprice%3D

or this one (only available as 4k7 which is probably near enough)

http://www.bardwells.co.uk/detail.asp?stockid=SURP08&ref=subcats.asp%3Ft%3D%26qfcode%3D%26catid%3DSURP00%26manuid%3D%26keywords%3D%26minprice%3D%26maxprice%3D

I have just ordered some of the switches and pots.

Richard
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Netleyned

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Re: Radiolink - T4U Review
« Reply #17 on: January 08, 2011, 06:47:40 pm »

Maplins have a range of pots submin
4K7 is a preferred value the next up would be 5K6
They fit in the GC transmitter ok

Ned
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smudge

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Re: Radiolink - T4U Review
« Reply #18 on: January 27, 2011, 04:06:33 pm »

hi there been totally new to all this can someone please answer me this question . i have a bait boat with two servos one for the rudder left/right and one for a bait release door and the motor which goes forward and in reverse . my transmitter and receiver need replacing and i was thinking of buying the radiolink t4u but I'm not sure if it would be anygood for the functions of my boat so can anybody advise me if it is or not. its probably a stupid question but i know nothing about RC stuff and dont want to end up with something thats no use to me . thanks all
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Re: Radiolink - T4U Review
« Reply #19 on: January 27, 2011, 04:27:54 pm »

T4U or T4EU as it is now badged is a four chan set and you only need three chans
As it comes L Hand Stick up & down for motor fwd and reverse (astern)
R hand stick L-R Port and Starboard
R hand stick up or down to drop bait

Simples!


Ned
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dodgy geezer

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Re: Radiolink - T4U Review
« Reply #20 on: January 27, 2011, 05:14:42 pm »

hi there been totally new to all this can someone please answer me this question . i have a bait boat with two servos one for the rudder left/right and one for a bait release door and the motor which goes forward and in reverse . my transmitter and receiver need replacing and i was thinking of buying the radiolink t4u but I'm not sure if it would be anygood for the functions of my boat so can anybody advise me if it is or not. its probably a stupid question but i know nothing about RC stuff and dont want to end up with something thats no use to me . thanks all

1 - if you can tell us what the model/make of your bait boat is we will be able to help you in greater detail.

2 - How do you know your Tx/Rx need replacing?

3 - If your bait boat uses a standard Tx/Rx, with standard sockets for the servos and speed control (and neither of these are broken), there is a very good chance that a new Tx/Rx will work (and the T4U is a very cheap example).

4 - If your bait boat is a bit non-standard, there may be more fiddling. In the worst case, you might need to replace all the electrics (the Tx/Rx, the speed controller, and all servos). That is still quite cheap to do, but you will need a bit more advice and guidance... 
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smudge

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Re: Radiolink - T4U Review
« Reply #21 on: January 28, 2011, 01:49:26 am »

thanks for replying dodgy/ i have a pondskater baitboat and i had a nav light not working and not knowing anything about rc boats i found a spare plug lead and assumend it had fallen out so plugged it in to the spare of the receiver resulting in the speed controller frying :-( only to realise later that it was the power lead from the front light. the receiver and esc was both burnt . i have had interference problems with this boat since i have owned it but it was a known problem with the early models. so while i need to replace the esc and receiver i thought i would go to 2.4ghz as i have read it would be more reliable and the t4u looks like it would be good but I'm just not sure if it would be able to do reverse as well as forward. as it seems the t4u is for aircraft and aircraft dont going in reverse. i have two servos one for rudder left/right and one that opens the door for bait drop  then the motor with an esc which goes forward and in reverse. so my question is could i set the t4u be set up to go forward and reverse left and right and open the bait drop door. now I'm confused so you must be. but forgive my ignorance i really am a total newcomer to RC boats and although its makes sense to me I'm probably talking garble to you.
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Re: Radiolink - T4U Review
« Reply #22 on: January 28, 2011, 06:28:09 am »

Sounds like the speed controller will need replacing!
You must use a marine type as it is the speed controller
that gives you ahead and astern
Does your speed controller have a maximum current (Amps) marked on it or does the motor have any markings
If you have the handbook/instructions that might give you the motor current
If you can supply us with this information someone on here will be able to steer you in the right direction


Ned
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dodgy geezer

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Re: Radiolink - T4U Review
« Reply #23 on: January 28, 2011, 11:13:18 am »

The Pondskater web site gives the motor spec as:

Motor: 755 - 7800 RPM unloaded, 9 W max. (6v DC)


A T4U would have no difficulty providing all the control necessary for this boat - as delivered it has 4 channels so it can control 4 items like servos or speed controllers. You need at least three channels. Is light switching a fourth? As was mentioned above, the ability to reverse is a feature of the speed controller, not the transmitter. 

However, if you are not very experienced at playing with radio controlled boats you might need a bit of hands-on help. Can you solder? You will probably have to do a bit to connect the motor up to a new speed controller... Note that redoing the insides of the boat will certainly invalidate any warranty you may have!

Any pictures you can provide of the inside workings of the boat will be useful - as would taking the boat to your local model boat club and letting them take a look. Where are you based?

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smudge

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Re: Radiolink - T4U Review
« Reply #24 on: January 28, 2011, 04:13:52 pm »

thanks for all the info i now understand how it works and will be ordering the t4u as it will do the job for me. i know i need a new esc and i have been in touch with a model shop in hull where i live and he is going to take a look at my boat and advise me on the correct one for me . yes the forth channel would be  for nav lights . I'm OK  at soldering so soon as i get the new esc and t4u i will be sorting it all out . thanks to all on here for the help you have saved me making some costly mistakes.
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