Hi redpmg
It may well work and I have heard of others who have used 40Mhz crystals.
The regulations are quite clear however and anyone trying this could find themselves in trouble if their equipment causes interference.
35Mhz transmitters are designed to work at specific spot frequencies within the allocated band, and will have circuitry to avoid or reduce any unwanted out of band harmonics being generated.
I would urge all our members to comply with the regulations that have allocated frequencies for specific purposes and allow all modellers to operate their models safely.
Dave

If you are lucky the 35mhz set should work with 40mhz crystals - most do - my 3 channel )single stick Hitec certainly does - even with other makes of receiver- difficulty is that its hard to find the crystals now - and when you do they are expensive . The 40mhz sets are still used by the Submarine fraternity as 2.4ghz does not work underwater. So if you are planning a Sub in your future suggest you keep the radio & find some 40mhz crystals.

There was of course the much earlier film (1954) - main character Harry Brubaker - The Bridges at Toko-Ri

Thanks Doug the 35mhz will be back on EBay! Incidentally most of us Bruce Baker's I reckon use the Brubaker moniker for one thing or another and yes a great film. All the best. 😎

Hi Brubaker,
(AKA Robert Redford?? Great film 😀)
Ref RC Frequencies, check this out.
https://www.rc-airplane-world.com/rc-frequencies-uk.html

or here for the official version with all the government blurb.
https://www.ofcom.org.uk/spectrum/radio-spectrum-and-the-law/licence-exempt-radio-use/licence-exempt-devices/Radio-controlled-models

Scroll to the bottom (past the blurb🙄) and click the 'What frequencies are available' box.
Cheers, Doug 😎
PS: For the record; from my Bookmark archive.

Hi Brubaker.
Oops.Dave is quite correct you can’t use 35mhz.
If you do you may have a Kamikaze aeroplane dive your boat.
There is a great deal of info on line re which frequency you can and cannot use.
Just type in your search engine Radio control boat frequency.
Good luck with your project.
Regards Bill.

Thanks Dave, especially re the 35mhz which I did not know about the only thing with that is the pots look the same as the Spektrum (externally anyway). I have looked inside the Planet with a view to simply turning the pots but on mine the 'upper' part of the pod is part of the casing the four screws merely remove the bottom half. I'll have a real look at the Spektrum next week (half-term) and attempt the 'mod' as necessary.👍

The 35Mhz can only be used legally in the UK to Control an Airborne plane, so please do not use with your model boat.
The Planet TS2+2 is a 2 stick 4channel and looks like there are four screws holding the stick units in place. The trim adjustment looks to be electronic so will not need to be rotated.
The Spektrum is 4 channel so will have two vertical sticks. It will already be bound to the receiver and there are details on-line how to, if not. This sounds like your best option
Dave

The original unit supplied by a dealer in Shoreham (UK) is a 'Planet TS2+2' which is the one I've described with the molded in pots. Now one by design and another by accident from eBay which before I do any dismantling look very similar. I picked up a 2.4 "Spektrum DX6" and by what I don't know I got a 35mhz "JR-Propo X-378" as well. Lots of notes on setting up drones and aircraft with both - the latter in 'Japanese'! I'll get the back off both of these next week and see what I've got. With the info you great guys have given I'm hoping to crack it. Just hoping I can bind the reciever OK or use the 35mhz which came with a receiver. Thanks again.😎

Yes unless you have bought matched motors they will start and run at different speeds. You may be able to adjust the ESCs to compensate.
You have a two channel radio with a vertical stick and a horizontal stick and I agree it will not be easy to sail with this set up.
I have in the past opened the case and just unscrewed the horizontal pot and turned it thro 90deg so it worked vertically. This may or may not be possible in your case, but possibly worth a look. If you use the transmitter for different models this could be a problem.

Now tank steering I can understand since I helped build em! Not the WW1 ones of course - Cents mainly. My trouble with this is that they are pod motors - supposedly matched but no amount of trimming can get the balance right - hence wanting to use the motors on individual controls - tried this with the RC set we got and it works well - except the 'pods' are molded in one L/R the other up/down - not easy! 👍

What radio transmitter are you intending to modify? It is difficult to give helpful advice without knowing the exact type of equipment you have. Chances are someone will have the exact same set and may already have made this alteration.
I use two sticks and have left one with the spring attached. I start the model using the free stick then adjust the speed with the spring stick. Makes it easier to control as you just need to adjust one stick when moving and stopping is easier as neutral is not always easy to find on free moving sticks, even with the help of the ratchet centre.

its called tank steering - which I suppose is teaching grandmother again - sometimes said it originated from the early tanks in WW1. 99% of the cheap RC boats seem to use it - if grandsons boat is an Airfix Severn it would probably have been cheaper to buy one of those and utilise the bits. Seem to remember Martin our small or unusual model expert used parts from a toy type for his mini pusher tug which he drove around in his Big Blue inland sea..................

If its a larger model Severn there are still some cheap NQD boats around which might fit the bill - a 30in cabin cruiser bought for me the better half was surprisingly cheap & has 40mhz RC. Lovely hull - so have been meaning to convert to 2.4ghz RC with rudders - but no place to fit them.........

Thanks to you all for your replies which are appreciated more than you will ever know. RC models are a 'dark-art' to me being delved into for an enthusiastic great-grandson. He has a 'Southampton' tug which I have cosmetically and operationally changed a little and provided a modified crew (from plastic soldiers) but attention's back to his 'Severn' lifeboat which has been a headache for years and has cost a veritable fortune in pension monies so far. Hopefully your replies will get me over the final hurdle. I especially like the idea of doing away with the spring and 'centraling' and instead modifying that one to match the 'friction' one - really had never thought of that and I reckon it will be easier in the long run to control the motors. 😀😀😀

This pics might give you an idea as well if you can't fit a spring (some TXs don't have a spring rocker fitted on the throttle pot,- and you probably can't fit one without disassembling the pot.) If you are lucky, your TX will have a ratchet quadrant on both sides (for mode 1 and 2 throttle set-ups) What you can do is copy the tensioner strip and fit it to the other side (gives you tension on each throttle stick, at least, but not centering) You should be able to do this if the bare side has a screw pillar to mount it on. I did a complete instructional on Hobby King years ago on this with a few other guys, plus changing a certain TX from mode 1 to ,mode 2 and vice versa, but it's all gone now. This is just an example, may not apply to your TX (don't know what you have)

Rowen has admirally covered what is required but you will need a small spring and possibly the arm.
A quick search shows Howes do stock such items
https://howesmodels.co.uk/product/volantex-exmitter-throttle-return-spring-for-ex6-ex7/
This may be suitable for your Tx as they are all fairly similar. Easy to remove the Tx back case and have a quick look.
Be aware though that there may be wires connecting bits between the two cases so make sure you don't pull on the wires especially any aerial connectors with small gold plugs. These use a snap connector and are very easily damaged. I use magnifying lenses when fitting.
If you are buying new the supplier, if a shop, may fit the spring for you, worth asking anyway.
Or you could take up Scratchbuilder's offer to supply parts from his surplus supplies, send him a pm.
Dave

From my limited Tx experience; the two lever assemblies will be almost identical, except one has a spring.
Dismantle the Tx and gain access to the lever assemblies.

Either : remove the spring from the motor control lever, both will now operate without springs (which is how mine are). Or, fit a spring to the second lever and it should now feel similar to the other.
The necessary notches etc for the spring are probably already there.

On your Rx fit your second ESC control plug to the elevator output socket. That lever should now function as a motor speed control, even if not marked as such.

If you are using the ESC BECC power for your Rx remember to disconnect one of the positive red wires.
All fairly straightforward fortunately