Globs

Posted by Mal Quelch on 17/08/2009 13:18:34: Another interesting (and important)  finding on the planet system concerns the failsafe.   Useful info. Funnily enough I was trimming out a friends helicopter tonight with a new Eurgle radio - quite a nice radio - but no failsafe at all!!.  Switch the TX off-on and the ESC just resets and starts up again, which is a bot spooky on a 2.4GHz system, particularly as I'm used to the Spektrum stuff which has a pretty sound failsafe..   So actually I'm impressed it has a failsafe at all

That doesn't sound good BB.Have you done an on-ground 300ft range check at all orientations? I'd be interested in the results..

Yes, I remember the old analogue continuous signal RF systems too well!! Thank God for the packet based spread spectrum technology  of today

Ken, the BMFAs insurance applies to all legal activity. Thus one leg would be the insurance, the other leg is that you are legal.If you modify your radio and it becomes illegal then you may be in trouble.  In that regard, while I cannot think of how a different coax could render a radio illegal, it could well attenuate the signal and reduce range. The BMFA club policy is to discourage the use of modified radios (at BMFA competitions etc) because of the (IMO) flawed 'advice' given by the Ofcom official.  I'm not really sure why Ofcom exist TBH, their fiefdom over broadband has been an appalling mess with un-controllable third party ISPs having more rights over people BT lines than BT or the line renter, and their inexcusable laziness in advising the RC hobby. Another one of the 1100 quangos we could do without.

Posted by flytilbroke on 19/05/2009 23:40:49: Not a legal move at all. Any claim against you in the event of an incident and you will NOT have a proverbial "leg to stand on". Any insurance will be null and void. Not true.  If your modification leaves the RF specification within the legal use of the RF spectrum then you are still within the law. It's THAT simple.  Modifying the coax however will mean the radio is no longer FCC or CE compliant, so you cannot do this as a business, but as long as you transmit legally, you are legal. The BMFA do not recognise any changes to any radio however, because they asked a jobsworth at Ofcom who obviously didn't bother reading any of the regulations, and just said it probably wasn't a good idea before driving off to a nice afternoon's golf. Regardless - the law is the law, and a legal transmission is STILL a legal transmission, regardless of how some people want to stop everyone doing anything remotely creative.

Posted by Kiwi on 16/08/2009 16:55:15: who is the distributor with a web site?  I cant find the brand your referring to and if I can get my dooks on a set I would run it over my scanner and do some range testing etc.    It is distributed by JP Perkins use Google or this Link

The latest batch of TXs apparently went via JP - so I expect they were busy re-badging them with the new plain badges, and their dustbins are stuffed full with the FHSS ones! I suspect someone complained - probably futaba I'd suspect.  If it uses a spare frequency it sounds like what the Assan ones do/try to do - for Assan I think it is a single hop if need be, maybe for this it can also hop back?  Anyone with (access to) a microwave spectrum analyser and microwave sig-gen here to test that? Although the futaba modules hops around using the proper FHSS pseudo random sequence a single hop should actually be enough in practice - indeed the Spektrum gear relies on one of it's two channels always remaining clear and that is pretty solid - in tests as solid as the futaba IIRC.  So I think although that cannot call it FHSS an adaptive DSSS is the next best thing and probably pretty difficult to break.  The main puzzle is how is manages good reception at all orientations with a single external antenna, is there an internal one on the PCB also? Has it got a super sensitive RF input stage? Either way - it seems to work impressively well and far better than the old 35MHz, plus at £10 an RX it's cheaper on receivers than my old RD6000, which now looks strangely cool with the 2.4 aerial on top As for recouping R&D costs - the 2.4GHz technology costs were re-couped a long time ago from the Wi-Fi industry, the use of them in RC is not a big step and would cost less I suspect than deveoping the rest of the TX, which they have also had time to recoup. A JR type futaba FAAST module costs £90, for £30 I can buy a complete TX, a 7ch futaba RX costs £63, for £10 I can buy a 6ch RX. A premium price of 3x to 6x actual cost (and remember that JP still make a profit with their Planet stuff) is too much, my personal limit is around 2x for a name. It's really a choice that the big brands have made - a higher cost per item for a reduced market share, but with the likes of Eurgle, Planet, Flysky etc they may have to start offering value for money and thus address a wider market to remain in the game for long.

I'd be interested to know how many channels the JP/Planet system hops around if you can measure that! I used to like futaba, their transmitters rocked. Then they went bean-counter-plastic, and the last one I bought was the Attack 2DR (for a car) and it was rubbish, totally exceeded by Sanwa and Acoms quality by miles. However good the technology is between the $5 radio modules I can't pay real money to have them surrounded by cheap plastic, joke model memory and a massive premium..  Another issue with futaba is their RX prices - what's all that about?? If they really wanted me to never buy another futaba system - I'd price them where they are now  Spektrum are not too bad - I have some spektrum gear, but I quickly tired of paying for new AR6200s when the turborix RXs were less than 1/3rd of the price. The Assan/Corona modules etc are good, but for £30 for the TX module (packed in a nice case with gimbals, switches etc) and £10 per receiver - the Planet series is quite stunning value for money. Now I have the superb RD6000 using it I'm really happy with the system that JP have allowed me, no binding button also makes conversion easier!!!

Ok - an update to the JP/Twister Planet 5 2.4GHz FHSS £40 radio system. I ordered one of these and eventually got one - they are in great demand!!Well the business part - the part that establishes the radio link is postage stamp sized and sits just behind the led on the front panel. In fact that led is driven by the RF board and blinks rapidly on start-up (bind mode) and then (if fed the proper PPM signal) switches to a solid red.  The RF board takes 5v and accepts a negative going (i.e. mosty positive but with 0V spikes) PPM pulse train to convey the stick controls to it. To use this in another transmitter you need to: Open up the case, unclip the 2.4GHz module, unplug the gold antenna plug, and unplug the black/orange/red plug.  Liberate the aerial.  So I open up my RD6000 Sanwa computer radio, cut the +ve track to the RF section (so it is completely dead) add a 7805 regulator to power the RF board, and hunt around with an oscilloscope for a -ve going PPM pulse train. Once found that was also connected - and after a little mechanical modelling everything fits in fine. Note: so not use the buddy lead signal - it is about 9V, find a 5V one.   So now I have a fully functional FHSS 2.4GHz TX that has all the toys of the RD6000 - like the computer radio, model memory, superb gimbals etc. And you know what? Yup - every new model just needs another £10 receiver.  Thumbs up for the planet 9! Compliance: Remember to use the original coax and antenna. 1. FCC compliance is based on the module and aerial system remaining untouched.2. CE compliance is based on it being mounted in a 'substantially similar' device - which is the RD6000 TX.3. Legality is assuming the original RF character of the donor Planet 5 is legal. So I now have a legal and CE/FCC compliant system too, which is nice.  

Just as a note, do NOT buy anything from www.modelshack.com (they advertise this radio).   They do not read email (2 of the three addresses bounce also), their 'contact' page on the website does not work, and their telephone number (the correct one) does not accept incoming calls.   Plus I ordered a radio on the 10th and it has not arrived. I phoned up the pub next door today, very helpful, the shop has been closed for about two months now...   Looks like I'll be cancelling the credit card payment now.

Basildon Biggles Where did you get yours from??   I tried ordering from www.modelshack.com but  after some time have no radio, I cannot phone them or email them or contact them via the website.   I still want a radio however!!

There is a big following of using the 2.4GHz modules used in the cheaper radios (or supplied as modules by Assan) and transplanting them into old but good 35MHz radios.   This then gives you a source of cheap 2.4GHz RXs and your nice gimbals, computer etc of the 35MHz donor transmitter.   The modules accept PPM signals like those either going to the original 35MHz RF board or with PCM transmitters use the PPM signal at the trainer port. If you maintain the 2.4GHz module, coax and antenna you ensure the legality of the signal (assuming the donor 2.4GHz stuff was legal in the first place)!   Transplanting stuff raises questions of certification. Reading the actual rules it appears that for the FCC regulations, the module is the test item so if you keep it intact (as described) you still have FCC compliance. For the ETSI regs with CE marking the RF module has to be in 'substantially similar' equipment. I view one TX being substantially similar to another.   Then you can buy a cheap 2.4GHz system (that you are confident of) and upgrade your 35MHz stuff to 2.4GHz for very little money!  

My 'Planet 5' will have a 6 model memory and computer control. It will in fact be exactly the same functionality as my RD6000, complete with digital trims and full mixing etc.   Whether it will still be CE compliant (certainly it can be read that way) or FCC compliant (rather likely considering the wording) or legal (extremely likely unless you tamper with the internals of the  2.4GHz RF module) is discussed further here.   Ofcom's interpretation and the BMFAs may be more relevant to you of course but that is just another interpretation - and differs from my own now having read some of the legal documentation.

Timbo: My/our needs are modest, I need some 6channel full range RXs for my DX7. If they were £35 I would have just bought them, but the AR6200 is now retailing at £53. Looking at the AR6200 I'd say the BOM cost is around $6 tops. £10-£15 appears to be the alternate cost.   The 'Should spend more' argument is great (and one I usually agree with) but if thousands of years of human nature has taught us anything, it has taught us that we will avoid expense if it seems reasonable to do so. So regardless of dubious claims of 'dodgyness' it will and is happening.     Ultymate: The Assan modules are CE and FCC certified as modules, therefore I believe they are legal to use in the UK. In fact to sell stuff in the UK it has to be CE certified so all the cheap chinese stuff now appearing in the shops will be CE certified. Also CE certification is NOT a measure of performance, but of conformance. Look for the CE label on the packaging and item.   Note: I am not a lawyer and have not read the relevant UK and EU legislation. If you hear legal advice make sure you get it from a lawyer who has read the legislation, not someone who wants you to carry on buying their expensive 2.4GHz radio gear, despite being unable to stop you using the much less secure 35MHz.... or the cheap non-computer 2.4GHz stuff they sell. Oh the irony! Perhaps their thumbs are also CE marked? If you want to use a totally unmodified setup then you need to make up a trainer lead or use a plug in TX module (from Spektrum, Assan etc). As far as swapping bits around I suppose the 35MHz equivalent is using a Hitex RX with a Futaba TX etc. or a Futaba TX with a Spektrum plugin. Is that against the BMFA rules? I do not know.   Physics and RF: At the end of the day whether you plug it into the back of the TX or install it inside, or use a trainer lead;- the exact self same radio system and protocol is being used regardless of whether it is housed in cheap chinese plastic of antique japanese plastic. I'd recommend you fly responsibly and do a proper range check at all orientations, just like you should with a top range Futaba 2.4GHz system.   Personally I'd rather my control (PPM) signal came from a quality japanese rig with expensive gimbals and pots than something thrown together by a tired assembly worker. 

Hi David,   I know nothing about the Jeti or Multiplex sorry! There is lots of people modding sets etc on rcuniverse and rcgroups, and the hobbyking forum is useful for Assan info too.   In general as long as a TX has a trainer lead (they usually use PPM) then you can mod it. If you get/make the right training lead then you also always have the option of simply using the cheap 2.4GHz TX as the actual transmitter, controlled via your computer 35MHz radio acting as a slave..   I'll put my module inside to replace the RD6000 RF board however as my RD6000 set only has 1 RX and it's much bigger than the 2.4GHz rxes. I'll also put the 2.4GHz antenna from the donor TX in the old telescopic hole, so the complete donor RF side (board, coax, aerial) is maintained intact (you should always do this!).   Cheers,   G

I like my DX7 too, although the old RD6000 35MHz fits more securely in the hands and the stick tips are more grippy too.   People have modded their DX7s with the 2.4 modules too however so they can use the cheap RXes in cheaper planes, the interface on connector J2 is the simple plus/minus/PPM as usual (black/red = +/-, yellow = PPM). The Assan is a direct fit but for the others you will need to manage the 5V supply and limit the PPM signal peak voltage to 3v.   I will have a look at the Planet 2.4GHz FHSS (Frequency hopping spread spectrum) and if the module is as small as the FlySky (iMax/Turborix/HobbyKing) 2.4GHz DSSS setup (Direct Sequence Spread Spectrum). If OK it will go into my RD6000 first, not the first time that lovely radio has been upgraded to 2.4GHz.   2.4GHz summary This seems to be the pecking order at the moment! (actually not in any order)   1) Twister (Perkins) Planet FHSS: Potentially the most robust signal but with a single (visible) antenna probably range is about the same. Good for long (glider) flights due to the frequency hopping. Failsafe unknown. 'Possibly' very robust link. Cheapest in the UK   2) FlySky (iMax/Turborix/HobbyKing) DSSS. No failsafe, but dual antenna. One 6ch receiver only (excluding iMax 9c) Relies on the inherent strength of the spread spectrum packet based signal to get through. Robust link.  E.g. much better than any 35MHz system. Small TX module will fit anywhere in recipient TX. Cheap RXs.   Corona etc I think are similar to this.   3) Assan modules. DSSS with redundant channel (one off use only). Many RXs and plug in modules for various makes of TX including the X8D hack module. Mid priced RXs. Has failsafe. Robust link.   4) Spektrum. Dual channel DSSS with multi antenna RXs available. Failsafe. Expensive RXs. Very robust link.   5) Futaba. FHSS with mult antenna RXs. Failsafe. Very expensive. Very very robust link.     I like 2.4GHz because the new "PPM in" -> "2.4GHz radio link out" make them very plug and play and allow us to mix, match and tinker with radios like we used to be able to do all those years ago. It also means that a fantastic quality TX that cost lots of money can be easily converted to DSSS or FHSS 2.4GHz now for less than the price of an AR7000 RX     ETA: DSSS and FHSS explained here Edited By Globs on 10/04/2009 10:21:12

The best bit about these cheap new DSSS and FHSS is that the RX and the TX module form the entire 2.4GHz radio system.   Like the old 35MHz boards you just feed the PPM data and power to them, with the odd Bind button switch and they do the rest. Most even auto-recognise the +ve and -ve PPM styles of the different manufacturers, you just need to make sure the PPM signal is about 3v (peak) for reliability.   Making it rather trivial to for instance upgrade your RD6000 or FF7 etc to 2.4GHz by replacing the RF board for the 2.4GHz module.   Assan even make FCC and EC approved 'Hack' modules for this purpose. These include the PPM level resistor divider/buffer and the stepdown 5v regulator.   Many people have used the Flysky model (HobbyCity/Turborix/iMax etc) modules for this and they work perfectly, as long as they are fed 5v power (from the donor TX's regulator) and 3v (peak) PPM signal.   Instant 2.4GHz as good as the original radios with your familiar computer radio. 35MHz computer TXs are suddenly much more interesting again as they suddenly become 2.4GHz systems with £10 six channel receivers...   If you really want to keep mods to a minimum simply plug a training lead from your computer radio to the 2.4GHz system and use the 2.4GHz to broadcast to the RX Edited By Globs on 08/04/2009 23:16:32