Model Boat Mayhem
Mess Deck: General Section => Model Boating => Topic started by: sweed73 on February 23, 2009, 07:46:01 pm
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HI i recently bought a 2 channel 27mhz model boat, it was home made and works fine,
i wanted to add some extra channels so i've bought a 4 channel 40mhz transmitter, the model says fm ppm ct2099,Item number: 180326198686
i also bought a 40mhz rx from sunupp available off ebay,Item number: 230323582476
i then bought a pair of crystals channel 695 but i didn't understand about single and dual conversions,Item number: 280304261894
also the rx has a switch for choosing between futabo and jr
nothing works !!
any help as too where i'm going wrong would be great, keep reading but i can't seem to find a way of proving whats wrong.
cheers
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You really need the same make of Tx and Rx both 40AM or both 40FM and then you need a pair of crystals that are compatible with the Tx and the Rx.
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I'm curious about the words PPM ? It sounds like a mis-match to me.
ken
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Hi Stephen.
Can you say what make the crystals are,where you got them or provide a hyperlink to the supplier.
Can you not contact j40sun,ask him what frequency band he used the transmitter on and also what make of crystals he used for it.
PS a ppm receiver is ok.
pcm would not have been compatble with the transmitter
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Everthing, Rx, Tx, and crystals are all 40FM Ken.
They are all on Ebay using his reference numbers.
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is there anything i might need to do to " initialise "? the transmitter after the batteries have been removed, some sort of fail safe ?
or could the crystals not be single as it doesn't say.
is there any easy way to check if a transmitter is transmitting, the same with the reciever ?
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Nope!
Need more info on the crystals to at least get the receiver on track.
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the item number is 280304261894 on ebay uk
i'll try and contact the seller of the tx and see what make he used.
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So you are saying your 695 crystals came with your transmitter or what?
You need to know if the receiver crystals are s-conv or dual conv but you also need to know what radios work with the crystals.
ps
ok found the listing
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the radio came with no crystals, i bought the crystals off ebay, they don't say single or dual, i wasn't aware of the difference at the time.
i cant seem to find the make of a crystal that people use with that radio.
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The receiver is a good'un because you can switch to pos or negative shift to pick up your both types of transmitter.
The single/dual receiverissue you sussed correctly but the transmitter crystal has to match the handset as well.
If the crystals are dual converson they should be ok either way.I can't guess from any related equipment from your crystal vendor.
That is another query for you to ask.
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Hi, you are going to have a problem with that transmitter. PPM is a pulse modulation, generally found with rc planes, and helicopters. THe rx looks like its compatable, however, as stated by the ebay seller, he was using it with a rc helicopter. On such, the throttle stick has no self centring action, ( assuming its also a mode 2, uk spec, throttle on the left stick) with a rc helicopter, you have to be able to maintain throttle (headspeed) without needing constant pressure on the stick, so essentailly you can take your hand off the stick and it stays there. With a rc boat or car, the throttle needs to self centre, take your hand off the stick, it returns to centre (and stops!)
Generally, they also have a ratchet effect on the throttle stick. It should work, and some may come back and say it does not matter, but if you inadvertantly knock that stick, off goes the boat! I would not use it, it didnt cost you much, so put it down to a bad experience. Now, in the pic of the tx both sticks are central, he has taken a very clever picture!! If both stick have self centring he could not have been using it for a helicopter, as the heli gyro will not set unless the stick is all the way down, its a safety thing, so the blades dont start spinning when your face is next to them :}
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The problem as I see it, if you are in the UK and the seller is as well then the transmitter should not be a 40mhz set if it was used for a helicopter. 40 Mhz is reserved for surface use http://www.fai.org/aeromodelling/system/files/frequencies_GBR.pdf (http://www.fai.org/aeromodelling/system/files/frequencies_GBR.pdf). A radio for aircraft use is 35Mhz.
You need to check the band for the transmitter.
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With a rc boat or car, the throttle needs to self centre, take your hand off the stick, it returns to centre (and stops!)
Why? :o All of my boat transmitters have ratcheting throttle sticks, I think it's much easier than keeping a constant pressure on the stick. It comes down to personal preference.
Peter.
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Transmitter - 4 channel digital radio control hand set "fm ppm ct2099":
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=180326198686&ru=http%3A%2F%2Fsearch.ebay.co.uk%3A80%2Fsearch%2Fsearch.dll%3Ffrom%3DR40%26_trksid%3Dm37%26satitle%3D180326198686%26category0%3D%26fvi%3D1
Sunupp FM 40 MHZ 6 Channel Radio RC Receiver 800Meter :
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=230323582476&ru=http%3A%2F%2Fsearch.ebay.co.uk%3A80%2Fsearch%2Fsearch.dll%3Ffrom%3DR40%26_trksid%3Dm37%26satitle%3D230323582476%26category0%3D%26fvi%3D1
40 MHz FM Crystals Tx & RX 695 @ 40.695:
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=280304261894&ru=http%3A%2F%2Fsearch.ebay.co.uk%3A80%2Fsearch%2Fsearch.dll%3Ffrom%3DR40%26_trksid%3Dm37%26satitle%3D280304261894%2B%26category0%3D%26fvi%3D1
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Silly question, you have swapped the the Tx and Rx crystals around to check they are not marked the
wrong way round?
Dual conversion means that it's requires a special crystal if it's a dual conversion receiver ( my Hitec Laser 40Mhz set
used dual convention crystals in the receiver, normal, signal convention crystals don't work ).
The short answer may be to arrange to meet up with the local club or another modeller with 40Mhz radio and ask
him if he could help you sort out what's not compatible / not working.
Test 1: Ask if he can test your crystals.
Test 2: Ask if he can test your receiver with his crystals.
Test 3: Can he test your receiver with your crystals
Test 4: Can you test your Transmitter with your crystals.
It would be best if he could bring a spare set of radio rather than strip down his working boat.
... bring a bottle of wine or beer as payment! :-))
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I'm going to say it again before it gets lost....
Before doing anything else
CHECK THE BAND!! If the Tx was used in a helicopter it should be 35Mhz not 40Mhz.
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Well spotted Ian, the seller said it was a spare Tx for his Helicopter so it wont be 40Mhz but 35Mhz.
Will not work in a month of Sundays. :-))
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1. The transmitter is a cheap make of the type used with the "colco Lama 5 helicopter". It may be a short range and I wouldn't trust what frequency it is transmitting!
Bin it and put it down to experience - unless your model is only worth a few quid, in which case it won't matter.
2. The receiver is a 40Mhz (probably single conversion) FM version. It should be fine with Futaba crystals (Hitec can be funny sometimes)
3. The crystals are neither Futaba, Hitec or JR, the seller is selling loads of different frequencies so could easily have mixed them up before labelling. They may even be poorly made copies. Don't trust them (reason as 1.)
Go to Howes (or similar) and get a known make of Tx on 40Mhz with a Tx Rx pair of the same make crystals. Put the Rx crystal in your Rx and try it. If it doesn't work then, you may have to get another Rx. It's always best to get the Tx, Rx and crystals as a set. Saves a lot of hassle in the long run.
Danny
Ah - the joys of Ebay!
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Hi, the tx has a 40 mhz sticker on it , is there a way of making sure that it is 40mhz internally, i have ordered a set of 40mhz crystals from the same handset from someone, cost £5 they will be here tomorrow , there's a shop near me where they've said i can take the radio and rx in and they'll check em out, i am ok to use 40mhz as its a boat this is correct?
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Yes, 40Mhz is designated surface use (Land & Sea) in the UK.
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The receiver is a good'un because you can switch to pos or negative shift to pick up your both types of transmitter.
The single/dual receiverissue you sussed correctly but the transmitter crystal has to match the handset as well.
If the crystals are dual converson they should be ok either way.I can't guess from any related equipment from your crystal vendor.
That is another query for you to ask.
I'm afraid you have probably got another pair of single coversion crystals and they won't work with that receiver.
Your transmitter is either negative shift (system used by Futaba,Hitec,Fleet) and positve shift (JR,Sanwa) and the vendor of the 695 crystals or transmitter could have answered that.
I think you have a more than 50/50 chance of them being ok with the transmitter i.e. both transmitter and crystal pair being -ve shift.
Your receiver manually switches between negative shift (system used by Futaba,Hitec,Fleet) and positve shift (JR,Sanwa) but it is narrow band and requires the crystals to be a close match (10 ppm/0C) suitable for dual conversion.
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just run it by me again, the reciever is i believe suppossed to be single conversion, manually selectable jr or futaba, therefore the problem i believe is getting a crystal to work with the transmitter, by ordering a crystal set which has come from this type of transmitter do i not at least stand half a chance of it working the problem being if it works with the rx, which hopefully it will. does the tolerance only affect the system if its dual ? am i right that the rx can be only be dual or single , one or the other, but the transmitter will work on both crystals.
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You have a dual conv receiver selectable for JR or Futaba
You need dual conversion crystals which are more expensive and the transmitter crystal has to suit the transmitter (pos(JR/Sanwa) or neg shift(Futaba/Hitec))
Dual Conversion
A type of receiver that converts the incoming frequency through two intermediate stages. This tends to eliminate the type of interference known as "image". With high-precision components, it also allows the receiver to be much more precise in selecting the incoming channel it accepts. This is what helps the receiver to be very narrow-band.
from http://www.futaba-rc.com/glossary.html#d (http://www.futaba-rc.com/glossary.html#d)
What means "positive or negative shift" for a reciever. On English web sites, I can read receiver for FUTABA/HITEC or Airtronics/JR, is it very important? Which receiver I need for A Sanwa transmitter?
There's no difference on "positive or negative shift" for a receiver. People in France usuall use 41 MHZ. There will be no influence either positive or negative shift. Unless you use 72 MHZ or 29 MHZ, the Futaba/Hitec will be negative shift, the JR/ Sanwa(Airtronics) will be positive shift. As long as you use the receiver in PPM mode, that could be compatible with Sanwa transmitter.
from http://www.gws.com.tw/english/service/faq/e_faq.htm (http://www.gws.com.tw/english/service/faq/e_faq.htm)
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i thought the dual conversion relates to the way the signal is processed, not the fact they have a selector switch, the info i have on the rx is that its a single conversion rx,
http://www.rcgroups.com/forums/showthread.php?t=943803
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Dual coversion crystals are just to a narrow tolerance and should be in matched pairs.
They will work in single-conv receivers.
Don't take every forum post as gospel truth.
Your Ebay listing to me said dual conversion :-
Range: 800M
Narrow-band
Microprocessor decoder
HIgh inter-modulation and interference suppression
High adjacent channel selectivity and interference rejection
No servo jitter when the transmitter is switched off
Small dimensions and weight
Compatible all FM/PPM transmitters
Uses mini or standard sized crystals (not included)
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can you have a look at this set, its the same rx the crystal has su on it ? mean anything,
http://cgi.ebay.co.uk/Radios-Sunupp-40MHz-4Channel-Transmitter-Receiver-US_W0QQitemZ350170734479QQcmdZViewItemQQptZRadio_Control_Parts_Accessories?hash=item350170734479
if the crystals tomorrow don't work i'm going to get a cheap set like this to get started.
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I should forget all this on here and take it all to your local shop and let them check it out. :-))
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how about converting it into a viking funeral pyre ship, complete with tx.
should only take a second and would at least bring me some enjoyment.
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how about converting it into a viking funeral pyre ship, complete with tx.
should only take a second and would at least bring me some enjoyment.
No, just go to your local model shop and buy a proper transmitter that they can prove works with your reciver. Or just write the whole lot off to expereince and buy a Spectrum 2.4ghz set which probably works out cheaper if you need a lot of channels. That way you are future proofed and can get back to modelling instead of trying to make eBay gear work ! :-))
What were you going to operate on them anyway ?
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how about converting it into a viking funeral pyre ship, complete with tx.
should only take a second and would at least bring me some enjoyment.
Sadly I think that might be the best bet :(( My advice would be to go and buy a complete rig including TX and RX. That way you know they're compatible. I understand how these things work (at least I think I do) but I'd not bother with all this faffing about given that basic 40MHz sets are becoming much cheaper these days. That gives me the chance to get on my soapbox and say that if you can afford a bit more then I'd go for 2.4GHz equipment and forget crystals for ever :-)
HTH
Guy
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With a rc boat or car, the throttle needs to self centre, take your hand off the stick, it returns to centre (and stops!)
Why? :o All of my boat transmitters have ratcheting throttle sticks, I think it's much easier than keeping a constant pressure on the stick. It comes down to personal preference.
Peter.
Yes it is personal choice Peter, however I think you will find that every single rc plane or heli tx is ratchet none self centre, and "virtually" all shop bought car and boat tx is self centre, the original author appears to be a novice, so lets not confuse him eh? :-))
Good points re the 40mhz and 35mhz, I forgot to point this out, however some really cheap and nasty helis and planes from the likes of (oops nearly named large retailers!!) sell cheap junk rc stuff operating on 40mhz.
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got my single con futabo crystals today, still doesn't work,
the bloke i bought it off won't reply to emails for info on crystals,
got a nagging feeling he replaced it because it doesn't work.
going to buy a complete set tonight,
might have to be a cheap one again but i'm going to buy the lot together as a set.
oh well
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just spotted a pic of tx and rx for sale , includes single con crystals in both,
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Well I think you have,
- a working Futaba or Hitec clone transmitter,therefore works with unbranded negative shift crystal. :-))
- a working dual conversion(High adjacent channel selectivity and interference rejection ) receiver needing a dual conversion crystal based on the Ebay description. :-))
- two matched crystal pairs,most likely negative shift to be Futaba compatible :-))
But
With each frequecy,you need to get a dual coversion receiver crystal,and probably the Futaba one.That is the downside of getting a dual conversion receiver. :(( The benefits are well documented elsewhere.
I further think your transmitter and crystal pairs will be compatible with both the set you have seen and the set you gave a link to yesterday.
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Buy new !!
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Agree with Dicky,what your gonna spend to get it working,you can buy a 2.4 set for £30-40 now
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Agree with Dicky,what your gonna spend to get it working,you can buy a 2.4 set for £30-40 now
I agree that the best approach is to buy a complete set from a reputable supplier. that way you know that all items are compatible. just for interest I had a look on the Howes website and was shocked to see how much prices have increased due to the poor exchange rate. Even so a 2 channel set can be had for £36. Anyone who had the courage to buy a DX5e at Warwick last autumn for around £55 did well though. Howes list it at £85 today! WRT 2.4GHz for £30 or so, I've just ordered one of the Turborix sets and am waiting for it to arrive. It takes a different approach with no menus etc but programming via a USB link to a PC. I'm waiting to see if it's CE marked and therefore officially legal in the UK.
HTH
Guy
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I had noticed that the prices have jumped up a lot Guy,for the spektrum sets,will wait for your conclusion before i get a Tuborix set,
as even though they are cheap
are they any good
are they legal in uk
if not ,buy another rx for dx6i
Mark
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I had noticed that the prices have jumped up a lot Guy,for the spektrum sets,will wait for your conclusion before i get a Tuborix set,
as even though they are cheap
are they any good
are they legal in uk
if not ,buy another rx for dx6i
Mark
Hi Mark
Yes I suspect that it won't be CE marked. If it's not, my main concern is that it may produce more than the legal power limit. There's a reference on the website to "up to 800mW". The UK limit is 100mW.
Guy
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Can some one point me in the direction of a set that i can buy online,
needs are
1) 3 channels or more
2) decent range
3) for use on a boat in the uk
a link would be great then i can get something ordered and get all the rest back on fleebay.
thanks
by the way what does su stand for on a crystal
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Sweed
To get you out of trouble,buy a 2.4ghz set,no crystals to play with.
What is your budget to spend,to give members a price range to advise you,
Guy has recommened the spektrum dx5e which he has tested and gives more than you need,
or as said from others buy a complete set (non 2.4) tx/rx from shop retailer.
Put ad in wants/swaps for radio gear on the forum the guys on here must have a spare set to sell,
and they are honest
Mark
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As Mark has said, I'd go for 2.4GHz even though the prices have gone up. However I had a quick look around for 40MHz sets and the most reasonable I found meeting your spec is the Hitec Zebra 4 Channel 40 Mhz Radio Control Set With Servos. I'm not going to suggest a particular retailer but Google for it and you should find it at £47.
HTH
Guy
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I had noticed that the prices have jumped up a lot Guy,for the spektrum sets,will wait for your conclusion before i get a Tuborix set,
as even though they are cheap
are they any good
are they legal in uk
if not ,buy another rx for dx6i
Mark
Hi Mark
Yes I suspect that it won't be CE marked. If it's not, my main concern is that it may produce more than the legal power limit. There's a reference on the website to "up to 800mW". The UK limit is 100mW.
Guy
The 800mW is likely to be a typo because 800mW would would mean 70% of battery power is converted to rf power.No way.
I have not looked at other 2.4G radios in depth but they should have a similar efficiency(post coversion).
SU possibly Single conversion sconv or synthesised crystal (i.e. no crystal) or laxative(suppo crystal) or crystal for supo receiver or superhet crystal
2.4 G is forgiving if you are sloppy with motor suppression but not with subs.
40 fm with a dual conversion receiver gives what it says in the blurb.
The complete set you listed and other sets based on single conversion 40Mhz receivers do as far as the eye can see.
40 or 27 AM don't get a mention.
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on the 2.4 sets do none of them have crystals, do you pair them with the reciever themselves.
does this mean a 2.4 can be used for land, sea and air ?
just seen a set for around £50
EK2 0404G for the tx
EK2 0424 for the rx
this is advertised for a heli though,
will there be different sets for a boat.
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This is another set for a small helicopter.
Most of them are only ever used up to 20 metres away from the Tx so don't have to have a "normal" range.
I have a similar one (for a 'toy' heli) which I wouldn't dream of putting in a boat as I wouldn't trust it for range.
2.4GHZ is legal for air (planes and helis) and surface (cars and boats) so a good one will be useful if you ever decide to diversify.
Bite the bullet and get a Spektrum DX5i, or go 40MHz with Futaba, Hitec, JR.
Danny
Oh yes - the 2.4GHz operate in a different way so, no you don't need any crystals (or to worry about frequencies)
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The 2.4ghz do not use crystals,but come with a tx that you bind with the rx (complete set).
Forget about if its for a helicopter,they have lots more settings than a boat,unless you want it to leave the pond,
my dx6i could drive me to work if i let it :}
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I got one of those Sunupp 40meg RX's and it also did'nt work, contacted the seller, did not get a reply so that speaks volumes to me >>:-(
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There are so few English language rereferences to Sunupp and so many possible crystal/transmitter permutations that I would not even buy a comlpete Sunupp transmitter/receiver/crystal from the Ebay suppliers.
As far as the parts you have,if the vendors can't or won't tell what associated branded r/c gear works with the individual elements then the previous Ebay auction winners might.
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on the 2.4 sets do none of them have crystals, do you pair them with the reciever themselves.
does this mean a 2.4 can be used for land, sea and air ?
just seen a set for around £50
That was probably the Spektrum DX5e but the price has gone up, though I'd still recommend it (except for submarines!). Without indulging in too much self-publicity, if you want an overview of the present state of play you could look at this link
http://www.modelboats.co.uk/news/browse.asp?at=12&p=4
and read the article on r/c today.
The site's well worth a look anyway since Colin has given it a much needed "wash and brush up"!
HTH
Guy
Guy
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Hi guys,
Stallspeed..... would you please expand on the following statements..... they don't make much sense to me.....
"Dual conversion crystals are just to a narrow tolerance and should be in matched pairs".
Even single conversion crystals are to a pretty tight tolerance and must also be in matched pairs.
"They will work in single-conv receivers".
Please explain how ?.
"a working Futaba or Hitec clone transmitter,therefore works with unbranded negative shift crystal".
What is a negative shift crystal?
"a working dual conversion(High adjacent channel selectivity and interference rejection ) receiver needing a dual conversion crystal based on the Ebay description.
two matched crystal pairs,most likely negative shift to be Futaba compatible"
Why do you need 2 sets of crystals? and again what is negative shift?
"But
With each frequecy,you need to get a dual coversion receiver crystal,and probably the Futaba one.That is the downside of getting a dual conversion receiver".
So what is different here?...... you would also need to get separate pairs for each spot frequency used, even using a single conversion set-up.
"The 800mW is likely to be a typo because 800mW would would mean 70% of battery power is converted to rf power.No way".
How do you figure this one?.... what else would the TX battery power be used for?
I look forward to your expanded reply.
Best regards.
AlexC ok2 ok2
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All crystals (should) have a number stamped on them indicating their resonant frequency. The TX crystal indicates the frequency transmitted to air, whether it AM or FM. The S/C RX crystal matching has a number offset by 0.455MHz. There is a local oscillator in the RX that this runs, the output is mixed with whatever comes from the aerial, (your TX signal plus everything else in the world) and is passed into an amplifying filter, called an IF stage. This is tuned to 455KHz, and, due to some magic maths, amplifies your signal and almost nothing else.
A dual conversion set repeats this performance, making the "almost nothing else" into "nothing else". There are usually two frequencies involved in this, using a bit of magic electronics it can be done with one crystal, but this needs a different offset to that required for single conversion. Different manufacturers tend to come up with different answers, so while single conversion crystals are fairly universal (honest!), dual are not, and should be regarded as manufacturer specific.
I remember seeing a Futaba list a while back (but can't find it now of course) where both dual and single sets were listed. The TX ones were the same part number for both, but the single and dual were different.
Not all of the TX battery's power goes up the aerial, quite a bit vanishes into the electronics.
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All crystals (should) have a number stamped on them indicating their resonant frequency. The TX crystal indicates the frequency transmitted to air, whether it AM or FM. I remember seeing a Futaba list a while back (but can't find it now of course) where both dual and single sets were listed. The TX ones were the same part number for both, but the single and dual were different.
I have two models that I run on the same Xtail numbers but it was only by mistake I found out that single and dual Xtails are different, I have one of each though not sure how I cam by the dual one. the trans Xtail is so hard to change is why I have several rx Xtails all the same (but one which is dual) I can leave them in the model and just switch on the next.
R,