Entry level transmitter

[lbl25a]

Looking for a transmitter for my next electric heli.

It must also fly my Esky Honeybees so 2.4 Ghz is out for the time being. I shall probably end up with several transmitters as money is not really a consideration - value for money is as I don't like to waste it!

The choice seems to be Futaba 6EXH or Hitec Optic 6. I am inclined towards the Optic 6 with Spectra Module as this would presumably work with existing Esky RXs without needing a matching Crystal, but am open to any suggestions other than buying a Nitro Helicopter.

[Disc]

I would recomend the futaba 7c

About 100 pounds from inwoods and is far better than the optic 6 (spit and cursing) Or the Futaba 6exh.

The diffrence is amazing but blows both of the the two your surgesting away.

But 100 pounds from inwoods it is well worth it!

[jimbob]

Just an aside, a problem with the FF7 is that it doesnt have a module, so you wont be able to convert it to 2.4 later.

Just a thought

[Disc]

Okay taken from the BMFA Website

Read it carefully and then consider would you REALLY want a module in a 35Mhz Tranny....

So here it is ripped from the BMFA WEbsite:


As someone who has been designing R/C equipment for over 30 years, perhaps I can add a little to this discussion and clear up some misconceptions......

The way that information is transmitted in the 2.4 GHz band is completely different to anything we have used before. Whether it be 27 MHz, 35 or even 459, we have always had to work within very narrow channel spacings, usually 10 KHz (on 35 MHz) or 25 KHz (on older 27 MHz and 459MHz). On 2.4 GHz, we have about 1MHz of bandwidth available for each channel! ie, each channel on 2.4 GHz gives us more bandwidth than ALL of the 35 MHz channels put together!

The upshot of this is that we can transmit data much faster, and we can also include "redundant" information for error checking.

However, to make use of this facility means that the whole encoding process at the transmitter is fundamentally different from anything previously used!

Whilst it is perfectly possible to design a plug in module for an existing transmitter, by doing so, you throw away many of the advantages of the new system!

The fastest data rate on a "conventional" system occurs when we use good old fashioned PPM. PCM is always much slower, as you have to transmit many more "pulses" per function, and the bandwidth restricts the rate at which you can transmit these pulses. This (plus the fact that PCM numbers have to be decoded back into variable width pulses) is why there is always a small but perceptible delay between moving the sticks and the servos responding in any PCM system.

So, to get the best out of a "module" 2.4 GHz system, you must set the Tx to PPM. The module will then measure the pulse widths, and re-encode this into whatever system it happens to be using. However, PPM only outputs at a rate of about 50-60 frames a second! A standard 2.4 GHz system is typically over ten times faster than this (maybe as much as a hundred times faster)! So using a module in a current transmitter is a bit like buying a V12 Jaguar, and then removing 10 of the spark-plugs!

The high data rate on 2.4 GHz is why pilots have been commenting about how responsive it feels compared to a standard 35 MHz system. Don't expect this to apply to a module system! At best, you will match what a PPM system can achieve, although there will be added security over PPM.

I can foresee a new generation of transmitters being made that will detect whether they are using 35MHz or 2.4 GHz, and adapt their encoding accordingly. But don't expect a current transmitter with a 2.4 GHz module to be as effective as a dedicated 2.4 GHz system.

Some other things to bear in mind: 35 MHz is exclusively for model aircraft use. 2.4 GHz is shared, just as 27 MHz and 459 MHz are. At the moment, this isn't a problem, as most 2.4 GHz usage is for things like wireless LANs on computers - not the sort of things you are likely to find on a flying site out in the sticks somewhere! However, this is no guarantee that this will always be the case! Nobody expected 2.4 GHz to end up being used for model control, and there may be someone else out there at this very moment, designing some obscure use for 2.4 GHz that hadn't occurred to any of us, but might have a major impact on our usage of it! Its SHARED, so we won't be able to complain!

Radio frequencies are tools, and just like any other tool, if you use the wrong one for the job, you will end up disappointed! I'm not knocking 2.4 GHz. I think its a wonderful step forward. But don't expect it to be a universal panacea for all the ills we *think* 35 MHz suffers from. Its a case of "Horses for Courses"!

--
Pete Christy

[Disc]

Please note I have posted the same thing here:

http://www.rcheliaddict.co.uk/showth...?t=3476&page=3

to keep it with the 2.4ghz debate

[jimbob]

That is all valid stuff disc, and I agree totally.

BUT... I for one have a load of 35Mhz Receivers. If I want to take advantage of 2.4Ghz, I have to swap them all, and my almost new FF9 which I dont want to do. I have something like 22 models programmed into my Tx.

SO... if you use a module system, you can switch it all at your own convenience. You can use the same Tx for both systems which is a convenience in itself. You can start to use 2.4Ghz gear, invest in 2.4Gh Rxs, and then when the time is right, upgrade to a 2.4G Tx.

The real benefit of 2.4Ghz is the channel allocation system - the fact we dont need pegs, and the frequency diversity helping with interferance rejection.

Have you or many others really been worried about latency before the 2.4Ghz bandwagon came along? I doubt it

[Disc]

That is all valid stuff disc, and I agree totally.

BUT... I for one have a load of 35Mhz Receivers. If I want to take advantage of 2.4Ghz, I have to swap them all, and my almost new FF9 which I dont want to do. I have something like 22 models programmed into my Tx.

SO... if you use a module system, you can switch it all at your own convenience. You can use the same Tx for both systems which is a convenience in itself. You can start to use 2.4Ghz gear, invest in 2.4Gh Rxs, and then when the time is right, upgrade to a 2.4G Tx.

The real benefit of 2.4Ghz is the channel allocation system - the fact we dont need pegs, and the frequency diversity helping with interferance rejection.

Have you or many others really been worried about latency before the 2.4Ghz bandwagon came along? I doubt it

Nope I don't care about 2.4 to be honest 35mhz does me fine for now and its that simple.

All he asked for was a cheap tranny the 7c is best priced one period.

Stick a module in a Futaba or JR and 10w see how it goes before its out of range. modules are not the same.

If you want to change then sell all your 35mhz stuff while its gonna fetch a good price and do the swap over. I am staying with 35mhz for now until theres a 9c by futaba thats dedicated to 2.4 period oh and I need to change until then 35mhz is fine thanks.

shouldn't this be in the 2.4 forum?

[Kisana]

I got a FF9 second hand as cheap now everyone going 2.4...
Get a £350 computer remote for £130 ish..

[kevinh]

I got a FF9 second hand as cheap now everyone going 2.4...
Get a £350 computer remote for £130 ish..

where from if you dont mind me asking

[Ade_Law]

pete christy is a memeber here. im hoping he might chime in

the DX7 has a ppm output through the buddy lead which is compatible with JR. that probably means that the RF part is still using the PPM signal. so surely there isnt actually a difference between something like the DX7 and say a JR9x with a 2.4gig module?

as for an entry level tx. i wouldnt go for anything less than a JR 9x or 9c if you can afford it. 2.4 modules available soon and you can stick your old 35mhz module in and use that for your old stuff.

if you dont want to spend that amount of money the 7c is the best bang for buck but doesnt have a changeable RF module so there is no option to go 2.4gig later down the line.

Ade

[Smoothound]

where from if you dont mind me asking

I have a JR PCM9X for sale currently, looking for around £160

[lbl25a]

Entry level transmitter.

Thanks for all your input Guys, very much appreciated.

One of the places where I shall use my transmitter is in the Spanish Villa which is on a hillside with no landlines but very close to wireless transmitter masts used for providing wireless internet and telephone connections to the residents including us. This does throw doubt on the 2.4Ghz suitability and possibly even synthesised transmitters?

I know that Futaba are compatible with the 4 in 1 used in the Honey bee so shall now go FF7 or FF9. Is there anything between them other than the extra two channels and the option of an interchangeable module?

[Smoothound]

You can never have too many channels but you can have too few