Good point, the cheaper 27 & 40 meg sets seem to have suddenly disappeared from mainstream retailers.

Sussex Models have one 40 meg set left:

**LINK**

Otherwise it does rather look like you will have to go down the Ebay route.

Colin

I wonder how many unused 27MHz sets there are stuck up in folks' attics along with the model aircraft kits that never got finished. I don't know of any manufacturer who still produces 27 or 40MHz multi-channel radios. I believe that limited stocks of the Robbe-Futaba F14 sets are available but I doubt it will be for long. As for "good-value" transmitters, the original Futaba Digimax 4 channel 27MHz AM sets were regarded as excellent value at £125 – in 1967! These days the equivalent of that would be £2,138… and 86 new pence.

Nothing will ever be as cheap again as it's been over the last few years. We'd all better get used to that.

Dave M

When I wanted a 40Mhz set for a sub, I went to Ebay Germany. There's often some good stuff there at cheap prices – I think they're holding onto 40Mhz longer than we are…

**LINK**

The German for 'Transmitter' is 'Sender'…

Hi. So why won't the sets work on sub? Is it to do with the frequency?

Bri

2.4GigaHertz is a vastly higher frequency than 27/40 MegaHertz. Low frequencies pass through fresh (but not salt) water relatively easily, 2G4 is in the microwave region. Microwave ovens work by having their signal be absorbed easily by any liquid inside the oven. Same with radio control signals. 1" of water absorbs enough so that there is effectively nothing left beyond that point.

Real submarines have the same problem – they have great difficulty sending or receiving when submerged.

That's a higher frequency and a lower wavelength. 2.4GHz is very roughly 100x 27MHz and the two wavelengths are approx 12cm for 2.4GHz and 11m for 27MHz.

That soldering job looks a swine to do, even for seasoned PCB assemblers like me. You can still only operate the model at periscope depth; if the Rx antenna submerges then the failsafe operates and the sub surfaces. I'm minded of Liz's observation that it's an expensive way to watch a piece of piano wire sail across a pond. Still, if that floats your boat – or rather sinks it……

I'd put a "Wanted" message for old VHF sets in the classified columns of Model Boats and RCM&E. Hardly anyone uses 27MHz these days so an old-ish 4 or 6 channel 27AM set would do you nicely. Just make sure it has 3-wire servos.

Bon chance, mon brave!

Dave M

The F14 sets can work out expensive. The optional expansions work very well but the decoder that plugs into the Rx to expand a channel are expensive or at least were when I when I bought one years ago. I think it was about £95 for the decoder and £30 -£40 for the module to fit the Tx . The Tx when you buy it is 4 channel with another 4 channels built-in to be expanded.

Tim

Tim
Much like the Trabant or Wartburg cars in the old East Germany, when there is quite literally nothing else available the concept of "cheap" vs "expensive" is meaningless. Even with the two proportional sliders to convert it into a 6-channel set the F14 is not expensive, especially when compared, say, with the top-of-the-line 2G4 Japanese sets whose transmitters alone are over £2K. Go and Google "Futaba 18MZWC" and see what some aeromodellers are paying! The F14 only becomes expensive when you add the modules to increase its functionality beyond 6 channels. The receivers were expensive c/w 2G4 ones as far as I can remember, so that would have to be budgeted for if you're not prepared to swap them from model to model.

Kevin
The whole subject brings me back to one of my main questions about boat modellers. Why are they quite happy to pay over £1K for a kit* and more for fittings and paint, yet they moan about the price of a radio being over £60 and buy their motors and batteries for pennies from unspecified foreign sources on E-Bay? I'm on the record as saying that if you buy the most expensive item then you might not get what you expected but if you buy the cheapest then you invariably get what you deserve.

{* Have you seen the clamour for Speedline's new Shannon kits on "the other forum"??}

DG
Much as I loved putting them together I can't see kit radios coming back. The cost of Type Approval killed them back in the 70's and it's still part of the law now. Hardware for transmitters is almost impossible to find for DIY assembly so you'd need a donor transmitter in much the same way as kit cars use a donor vehicle. Finally the necessary components are probably all obsolete by now – radios these days being based on single-chip SMT circuits. As for any commercial involvement, forget it! Ask yourself if you would break your neck to produce a working multi-channel VHF model radio for the sort of folk who want to haggle over the price of a 380 motor mount? No – me neither.

Dave M – Off to the pub before the ICBM's start arriving.

…submariners will have a problem eventually, they may have the transmitter but receivers will dry up eventually…

Er… everything I said about home kits applies to both transmitters AND receivers. A home made receiver is likely to be larger than the commercial ones, but not by much…

Andy – I bought a boat last year which came with an Acoms Techniplus AP-202 2 channel 27 Mhz transmitter and I think a Hitec receiver.

I'm going to change to 2.4 Ghz so if the Acoms is any good to you, you can have it. Though I guess 2 channels isn't enough for your needs?

Regards, Chris

Edited By Chris Fellows on 02/09/2017 23:34:01