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Advice on using my old Futaba gear

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David Ramsden13/05/2020 16:16:38
10 forum posts
5 photos

I'm returning to the hobby after 40 years and need advice please. I only need a basic r/c system.

  1. I have an old 35 Mhz Futaba FP-T5LK transmitter, P-FD56FM receiver, and FD33M servos, still working. The old Tx and Rx nicads will need replacing though. Is it worth spending on this or better to ditch it all and move to a basic 2.4GHz system?
  2. Will my old FD33M servos work with a Futaba T6L Sport 2.4GHz T-FHSS & R3106GF Receiver? Do I just need to buy plug converters and if so where? Or is it better to ditch the old servos because modern ones are so much better?
  3. I don’t understand why modern Tx & Rx systems seem to use disposable dry cell batteries. Can a Futaba T6L Sport 2.4GHz T-FHSS Tx & R3106GF Rx be easily converted to rechargeable batteries and will they work just as well? Is there a reason they use dry cells?


Jesus Cardin13/05/2020 21:19:05
79 forum posts
17 photos

David, first of all welcome to this forum and I wish you have a grateful return to the hobby!

Regarding your questions:

1.- I would recommend you to go for a new equipment if you want to go flying safe and soon. Anyway you should keep the old system as if in the future you would like to properly fly vintage models. tackling with the old system will require knowledge, experience, time and money that probably you should better use getting the new 2.4ghz system and building your new model plane.

2.-Sure they will work but again you will need buying plug converters or -as I prefer- to cut the servo cables and solder new ones with moderns connectors. Again work and expense for 35 plus years old servos that may fail at any moment. Today you may purchase smaller and reliable servos very cheap so, again, I will not bother with the old servos but get some new ones.

3.- Really modern R/C systems do not generally use dry cells but Ni-MH, Li-Fe and Li-Po rechargeable batteries. Only simpler and economical radios like the Futaba T6L Sport are so designed and unfortunately not, it is not easy to convert that transmitter to rechargeable batteries (if I remember correctly it even does not include a charging jack!). On the positive and due to the relatively low RF power of modern radios and as the T6L does not incorporate a screen, a set of 4 good alkaline dry cells will give you service for a total of nearly 5-6 hours of continue use. Regarding the receiver it just require a battery of any kind up to 8,4V (please, check servos voltage tolerance) connected through a good quality switch and you are done!

Sincerely hope these lines are of help for your decision and, please, take care and keep healthy.

Simon Chaddock13/05/2020 22:33:05
5708 forum posts
3029 photos


I would have to agree with Jesus an FP-T5LK probably is getting a bit old. Not only wear but corrosion has to be taken into account. It anything on the transmitter fails, you would be very lucky to avoid a serious crash.

As stated about the only justification would be to use it as 'period gear' at a vintage event but then it would only be done with care and expert knowledge.

Much better to get yourself modern 2.4 equipment. Not least as many othera will have the current knowledge to help you with any problems. wink 2

I do use a 35 Mhx Futaba Skyport 6A on a few simple planes but it is used with modern (relatively!) receivers and servos. The biggest drawback is each plane has to be set up in exactly the same way.

My 2.4 stuff has 'memories' so the transmitter set up is unique and can be completely different for each plane.

I hope this helps.


Edited By Simon Chaddock on 13/05/2020 22:34:37

Nigel R14/05/2020 07:21:35
3881 forum posts
667 photos

Hello and welcome

Much has changed in forty years!

I'd agree with the advice above. I would have concern over the radio. Components age, mechanical stuff gets dirty (pots, switches), corrosion happens and sometimes not obviously.

The servos could be used but again there are modern equivalents available for much less money.

Jon - Laser Engines14/05/2020 08:48:21
5481 forum posts
268 photos

If it was something like a challenger or FF6 you might get away with it but i agree with the other guys.

Modern radios are not expensive and something like the futaba t6k is not going to break the bank and will be much easier to use. **LINK**

You dont get servos with radios very often these days but that can be a good thing as you might not need full size servos depending on your model.

Some radios do use dry cells in the back but i would not recommend them for on board the model. A 1200mah 4.8v battery will power a 5 servo i/c model with standard servos for probably 20 flights so there is no need to go mad. If you fly electric its likely you will take power from the flight battery so you wont need an RX battery on board

Frank Skilbeck14/05/2020 08:57:58
4726 forum posts
101 photos

Couple of guys in the club have the T6K radios and have just replaced the dry cells with rechargeable Nimh cells, no problems they work well. I wouldn't use loose cells in a holder as a receiver supply, but in the transmitter I have used a set of Nimh batteries in a Dx6i for over 8 years with no issues.

Power consumption of 2.4 radios is very low and the T6L which has no display will probably be less than 100 milliamps.

If you do go with dry cells, then make sure you have a spare set in your flight bag/box.

ken anderson.14/05/2020 09:12:53
8680 forum posts
807 photos

welcome from me David,...up to you what you do and use...But, why spend a load of dosh on a new model and risk kapowing it using gear that is well past its sell by date? say you only need basic gear,for not a lot of money you can get a well specked set of radio gear that will do all you want and more.....maybe leave the old stuff for time to come or sell it and put the money towards some current stuff..

ken dept.

Cuban814/05/2020 10:13:54
2950 forum posts
1 photos

Personally, I wouldn't be happy with using a very old 35 meg system. What many don't realise is that components do deteriorate over the years and in the case of resistors and capacitors, can deviate well out of their original value.

I spent a number of years as a bench tech repairing industrial electronic measuring equipment, and a number of devices that I dealt with had failed or were unreliable because they were suffering from the effects of long term deterioration of components, typically after twenty, thirty or even forty years of use or being put back into service from storage by some parsimonious or stick-in-the-mud company owners. Expensive and time consuming repairs that made a tidy profit for my boss at the time.

My advice if anyone really wants to press an antique 35 or 27 system back into service is to (after new batteries & switches are fitted) range test the set and note the result - I'd expect between 30 and 40 paces with the TX aerial down and solid control at the servos in an open area. Extend the tranny aerial and with the TX and RX apart by as far a distance as  is practical (in your garden say) run the set through a couple of full battery charges and repeat the range test. If the set still gives a good range test as above with no glitching, then the chances are the set might be OK to use - whether it continues to operate correctly and for how long is anyone's guess.

Don't forget that we're obliged to ask ourselves whether we are reasonably happy that we can complete a flight safely. In the event of an incident, how would anyone explain away trusting very old equipment that is knowingly susceptible to deterioration? Would anyone trust a thirty years old set of tyres on their car/caravan/motorbike even if they looked ok and appeared only moderately worn and on the face of it, in good nick. How about  a gallon of 1980 vintage glow fuel?

Clean the set up and have it as a display item in your workshop and treat yourself to one of the new sets.......

Good luck David & welcome back to the fold.





Edited By Cuban8 on 14/05/2020 10:23:26

kc14/05/2020 10:57:28
6497 forum posts
173 photos

If you should decide to use 35MHZ then you need to worry about other pilots not using frequency control - they think they are the only ones on 35 now!

One of the possible but unseen problems is black wire corrosion on old eqipment. Especially on switch harness which should be discarded. Actually I found black wire corrosion on the red wire too on a switch harness. So put the old Tx on the antique shelf and buy a 2.4 ghz set which will likely have expo and lots of other handy settings. Most people won't be happy with less than 6 model memories.

Old servos might be OK if used just on non critical items - maybe throttle & rudder, but servos are cheap now. Test them and also new servos with a servo tester for half an hour or more. Just a couple of pounds for a servo tester from Banggood etc.

Buy a set of Eneloop (Panasonic) rechargeable but low self discharge batteries for a 2.4 ghz Tx. Note that if using electric power most people won't use a Rx nicad or switch but rely on the BEC from the ESC.

Check the price and availability of spare Rx before you decide on a brand of TX. Nowadays people have a Rx in each of their many models so price mounts up. Some are expensive , some have reliable, cheaper substitute Rx avail and some obscure systems become unobtainable quickly.

Edited By kc on 14/05/2020 10:58:29

Edited By kc on 14/05/2020 11:25:49

Dwain Dibley.14/05/2020 11:35:46
1497 forum posts
1487 photos
Posted by kc on 14/05/2020 10:57:28:

If you should decide to use 35MHZ then you need to worry about other pilots not using frequency control - they think they are the only ones on 35 now!

Valid point KC.......

I have just Bought an Optic6 35 Mhz Transmitter, to fly my old indoor stuff, all known quantities re reliability.

It is tempting to just switch on and go, but I have a frequency checker in my Tx box that cycles thru all channels just in case.

Nowt wrong with 35 mhz, it's still a valid genre, as long as you follow the advice in the thread/posts above.

Having said that, if I was starting new, I think I would buy a low end 2.4 set up (or the best you can afford, 9 channels seems to be the norm), and save the 35 stuff re the posts above.

Good luck and Welcome by the way LOL


David Ramsden14/05/2020 14:09:23
10 forum posts
5 photos

Thank you Jesus, Simon, Nigel, Jon, Frank, Ken, Cuban8, Kc, and Dwain for your advice and warm welcome – very much appreciated.

Sounds like I’m in the market for a completely new system. The T6K is recommended and Eneloop rechargables which are only 1.2v rather than 1.5. Is that an issue? I do think I’d like a system that uses rechargeables throughout. Surely a soldered battery pack is more reliable than an AA battery holder?

I intend initially to have 2 simple models, one glider and one electric, so I need Rx’s that can be powered by rechargeables or via the motor battery (plus one rechargeable Tx), dual charger, and a total of five servos. I don’t need a programmable system and I like the idea of ‘keep it simple’. I could move away from Futaba (perish the thought!).

If I insist on a Tx with a built-in soldered battery pack then the T6K is out. I do want to stick with a well-trusted brand and I’d quite like to support my local model shop **LINK** I await your best recommendations!

Thanks again,

Robin Colbourne14/05/2020 14:41:33
577 forum posts
17 photos

Hi David,

The Futaba FP-T5LK was my first 35MHz set, bought in December 1981, when I and the other first year RAE apprentices were taken to the Model Engineer Exhibition at Wembley Conference Centre.

One other thing I can add, is that the plastic moulding around the base of the sticks can crack and then the whole gimbal falls apart. I wasn't aware of the deterioration that Cuban8 describes, but given the possibility of that, it does sound like a more modern set would be a good idea.

If you are not keen on the idea of a programmable transmitter, then Spektrum and others do basic sets with reversing switches and mixers on slide switches.

I wondered if the lack of charging sockets on sets equipped for 4 AA cells is to prevent people trying to charge them with their existing transmitter chargers. I have a FlySky 2.4GHz transmitter (FS-T6) which uses eight AA cells and does have a charging socket; their later four cell FS-i6 does not.

Cheers, Robin

Frank Skilbeck14/05/2020 15:27:45
4726 forum posts
101 photos

David, yep the lower battery voltage is fine, the actual 2.4 ghz circuitry runs at 3.3v so this isn't an issue. Also on the T6K you can fit a soldered pack, it shows you how in the instructions.

For gliders it's a better bet than the T6L as you get aileron differential, spoilerons (crow braking if you have flaps), camber etc etc. Plus Vario if you have the appropriate sensor in the aircraft.

The thing that I don't like about the T6K is that for some reason Futaba made the trainer switch non-spring loaded and on the top right of the Tx, which is the opposite of what they previously did (spring loaded top left) which is what all our instructors were used too, so for that reason it isn't a very good instructors radio!

Steve J14/05/2020 16:17:50
1905 forum posts
54 photos
Posted by David Ramsden on 14/05/2020 14:09:23:

If I insist on a Tx with a built-in soldered battery pack then the T6K is out.

According to the manual, you can drop the dry cell box out and replace it with a 5 cell welded pack.

Simon Chaddock14/05/2020 18:01:32
5708 forum posts
3029 photos


As far as a simple electric power plane goes the answer is a motor speed controller (ESC) with BEC. The flight battery, which is a complete manufactured unit then runs everything.

Don't worry the speed controller is clever enough to cut the motor (some slow it down first and then cut it) before the battery gets exhausted. As the flight battery is big in comparison to a normal Rx pack there is plenty of power left for the control functions (10 minutes?) to fly (glide) the plane in.

This is about the simplest power flying you can get. Switch on the Tx, plug in the flight battery, check the controls and you are away.

Just as an aside. I use LiPo batteries anyway and have the chargers so I actually run my old 35 mHz Futaba Sport on a 2 cell LiPo (7.4V) 'Tx' battery which fits exactly. Has to be removed to charge but no great problem as it last for many weeks even in summer. The Futaba handles the extra volts (8.4 fully charged) no problem although the voltage indicator does show well over 100%!wink 2

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