Model Boat Mayhem

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Author Topic: Radio Gear  (Read 6834 times)

Ghost in the shell

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Radio Gear
« on: November 16, 2008, 04:31:20 pm »

All the talk about ESC's Rx's Tx's is bound to confuse you, so lets break it down into simple sections.

Transmitters:
this is the bit that you hold, often with sticks, though some do have a pistol grip, and come on a veriety of wavebands:
27mhz: European and usa surface band
35mhz: European Aeromodelling band NOT LEGAL FOR SURFACE USE
40mhz: European surface band

72mhz: US waveband - Aeromodelling I think and so not legal for surface use or use inside the European Union
75mhz: US waveband - Surface I think, not legal in the European Union

2.4ghz, this is new technology stuff, self seeking radio systems legal for surface and air, though not for submarines, though this is to do more with signal dynamics than legal mumbo jumbo, it simply can not penetrate the water.

apart from 2.4ghz radio equipment, everything else comes in AM and FM, and basically if you have AM transmitter you need AM reciever, as AM only works with AM and FM only works with FM, its a bit like trying to watch SKY tv on a Virgin cable box, it simply wont work.

Crystals:
more commonly known as X-tal, these again are tuned for individual frequencies and AM/FM, each hobby grade reciever and hobby grade transmitter has one, and are also specifically tuned to brands as well, so a Futaba FM wont work in a Hitec AM radio even if they are the same frequency. 

when you buy a pair of radio crystals, you will get two types, though they look identical they are different, marked up for transmitter and receiver, ensure that the "Tx" one goes in the Transmitter and the "rx" one goes in the receiver.

Receiver:
this little bit goes into the model itself, quite often it has a wire coming out of it. This wire is the antenna, be careful, dont damage it, it will also have slots in it, these slots will be numbered, with one being marked B.

battery packs:
these come in several types, for radio, they will be 4 and 8 cell, (the smaller 4 cell may be in some radios a cradle to hold 4x 1.4v AA batteries, with your 8 cell pack being replaced by 8x AA batteries in some low end radios such as the Futaba 2ER).  The term "cell" reffers to the individual elements within the battery, so a transmitters 8cell pack will be 8x AA batteries packed together to form an 8 cell pack, the 4 cell pack will be a smaller version with 4x AA packs,  these are rechargable and can be recharged with the charger that comes with your radio.

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andyn

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Re: Radio Gear
« Reply #1 on: November 16, 2008, 04:43:30 pm »

a Futaba FM wont work in a Hitec AM radio even if they are the same frequency. 

Ahh yes but they WILL intefere with one another...
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OMK

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Re: Radio Gear
« Reply #2 on: November 16, 2008, 04:50:04 pm »

"Transmitters:
this is the bit that you hold, often with sticks..........."


Ah, so that's what I'm doing wrong! I thought I had to hold it with me hands!
(Sorry, Ghostie - couldn't resist!)  %)

Nice thread. And don't forget to tell 'em about Hi-band/Lo-band, Hi-shift/Lo-shift, etc, etc.............
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Ghost in the shell

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Re: Radio Gear
« Reply #3 on: November 16, 2008, 04:53:03 pm »

lets not get toooo complicated


and yes I will be covering interference.
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Ghost in the shell

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Re: Radio Gear
« Reply #4 on: November 16, 2008, 05:06:26 pm »

ESC: the Electronic Speed Controller:

originally electric radio boats had a variable resistor, like what used to be in mechanical train set controllers, operated by a sweep arm these in the late 1980s gave way to smaller, lighter electronic units, which were back then quite expensive, though prices have tumbled, some even have a BEC on it, which means Battery Eliminating Circuit, what this means, your nice 4 cell battery pack you had with your radio, well you dont need it so put it on your shelf

These often have a mirriad of wires coming out of them, blue wire, yellow wire, red wire black wire and a 3 core ribbon, so what goes where?...

the 3core ribbon goes to the Reciever, where it takes its command signals from
the red and black wires go to the battery, this is where your esc takes its feed from, more often than not it has a tamiya plug on it. 
The yellow and Blue wires go to the motor, and are the output from the esc, so dont what ever you do, connect the battery to these wires, otherwise you will let the smoke out of the esc, which putting it mildly isn't good, the smoke needs to stay inside the esc for it to work.  (yes electronic items rely on the magic smoke)

Some of them may have a "set" button on them, please follow instructions of your esc as to how to set it up

one of the most common questions is: "If I have BEC on the esc, Do I still need the receiver pack?"
Answer: No, your esc provides power to the receiver but if you do want to use the esc and the battery pack, remove the red wire from the plug at the end of the ribbon and tape it back

another one that crops up is the use of multiple esc's that have BEC, such as the Mtroniks Viper range.  This is again not a problem, just decide which one is the master esc, and then on the others, remove the red wire from the ribbon tab

There are also coming onto the market brushless esc's, these are for brushless motors and originally came over from the aircraft scene, many dont have reverse so keep them for fast racing boats or model hover craft where reverse is not needed.

many esc's have a rating on them, both for output and input, example: 4.8v-12v 15a 4.8v is the minimum voltage this esc needs, 12 is the maximum, and will work quite happily on ni-cad / ni-mh packs and lead-acid packs, the output voltage will be the same as the imput voltage, however the output will be able to stand up to 15 amps, this means that if your motor pulls more than 15a, you need the next esc up, as if you pull more than the 15a, you will let out the smoke, same if you put too much voltage through it, (like 14.4v (2x 7.2v packs in series).

Electronic items work if the smoke is kept inside and cease to function if the smoke is let out
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Ghost in the shell

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Re: Radio Gear
« Reply #5 on: November 16, 2008, 05:34:05 pm »

Servos:
these little boxes are the bread and butter and give most of the muscle for the surfaces, and in some cases provide the muscle for the power as well.

on the top of them is usually a little cross head with holes drilled into them, and yes they also come in different sizes, sub micro to full size, in a model boat, you will normally come across standard size servos.  A normal use for the servo is operating the rudders and in some cases working sails on small model yachts.

Servos are best mounted with the control arm running in a straight line, this gives better efficiency and makes it easier for the servo to move the surface. 
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Ghost in the shell

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Re: Radio Gear
« Reply #6 on: November 16, 2008, 05:48:14 pm »

Interferrence:
we've all had it, and if you are new to the hobby, you will at some point get it, now what causes it?

on AM gear, one of the biggest problems can be the antenna too close to the motor, and other people on similar, and some times THE SAME frequency.

lets look at the possible causes:
motor interferrence:  short of putting your motor in a lead box, the way to reduce motor problems is to add supressor capacitors to the motor and run the antenna away from the motors, prefferably vertical up the inside of a mast if it can be done, though more often than not, supressors will do the job.

Frequencile interferrence:
This is where interferrence is caused by two radios on the same frequency in close proximity to eachother start operating, your model and the other persons model recive two different set of instructions, basically confusing your poor boat, this is why its always good to ask other modellers what frequency they are on, that way any one on the same frequency can either change frequency if you have extra crystals, or work out a sailing plan between you.  all because you are on AM and the other person is on FM, yet you are both on 40.665 for example, the frequency is still the same, and thus you will both interfere with eachother.

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Ghost in the shell

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Re: Radio Gear
« Reply #7 on: November 16, 2008, 05:56:03 pm »

phase-shift.

This isn't someting out of star trek though it may sound like it, but its all to do with how the signal is carried.  picture the waveband like an ocean wave, and the data being the message in the proverbial bottle, some radios work on hi-shift, some work on low shift, hi-shift has the bottle on the peaks of the wave, lo-shift, the bottle is in the trough of the waves.  Some manufacturers preffer hi-shift, others lo-shift, so because of this, it is best to keep your transmitter to the same brand and modulation type as your reciever.
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malcolmfrary

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Re: Radio Gear
« Reply #8 on: November 16, 2008, 06:04:02 pm »

Dont forget the beginners who have a low-end RTR.  The radios in these are usually designed to a minimum price, and this shows in performance.  The transmitter can't chuck the signal very far, and that signal is very prone to being swamped out by a hobby quality transmitter anywhere in the band.  Fortunately, they rarely have the ability to interfere with our gear....
The receiver aerial up the inside of a plastic mast is OK, up the inside of a metal mast, you have just reinvented the coaxial cable, which was designed to not pick signal up.
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Ghost in the shell

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Re: Radio Gear
« Reply #9 on: November 16, 2008, 06:07:18 pm »

LEGAL MATTERS

The European Union, The United States and other countries both have their dedicated frequencies for the operation of radio control models, these frequencies are split into two areas, SURFACE and AEROMODELLING.  In the UK there is the BMFA and in the USA the AMA, these govern aeromodelling, and have a code of conduct to adhere to, We in model boating dont have such a code of conduct to adhere to, however we still have to be aware that we are not legally permitted to use aeromodelling frequencies for our model boats, just as they are not legally allowed to use surface modelling frequencies for their aircraft models. 

OPERATING A MODEL BOAT OR CAR ON AN AEROMODEL FREQUENCY CAN LEAD TO CONFISCATION OF RADIO EQUIPMENT, A RATHER HEFTY FINE AND MAYBE PRISON TIME IF INJURY OR DEATH IS CAUSED, OR ALL 3

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Ghost in the shell

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Re: Radio Gear
« Reply #10 on: November 16, 2008, 06:11:50 pm »

Dont forget the beginners who have a low-end RTR.  The radios in these are usually designed to a minimum price, and this shows in performance.  The transmitter can't chuck the signal very far, and that signal is very prone to being swamped out by a hobby quality transmitter anywhere in the band.  Fortunately, they rarely have the ability to interfere with our gear....
The receiver aerial up the inside of a plastic mast is OK, up the inside of a metal mast, you have just reinvented the coaxial cable, which was designed to not pick signal up.


aaah yes thanks for reminding me about low end stuff

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The long Build

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Re: Radio Gear
« Reply #11 on: November 16, 2008, 06:16:36 pm »

LEGAL MATTERS

How does this work , if you are operating  A Shorts sunderland flying boat/plane  on the water , but do not intend to fly. If I was to use 35mhz   (Serious Question)
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Mankster

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Re: Radio Gear
« Reply #12 on: November 16, 2008, 06:20:49 pm »

27mhz is legal for air as well and 40mhz is not legal in France.

mick

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Re: Radio Gear
« Reply #13 on: November 16, 2008, 07:13:01 pm »

35mhz is used for aircraft, if your flying boat does not fly, use 40mhz...mick
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Ghost in the shell

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Re: Radio Gear
« Reply #14 on: November 16, 2008, 07:14:40 pm »

why does France have to be different?

as for operating a sunderland flying boat on 40mhz, to be honest, its probably better operating it on 35, it looks like a plane, so if any do-gooder ukra guy sees you on 40mhz, that'll be a fine, it would in my oppinion be better on 35.

Roger in France, this is for you, whats the main french surface band, i was under the impression that 40mhz was all of eu?
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Ghost in the shell

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Re: Radio Gear
« Reply #15 on: November 16, 2008, 07:15:59 pm »

however try mick proving that your model plane doesn't fly to the ukra when they come to you for operating a plane on 40mhz when it has wings?  that is a very very grey area. 
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Subculture

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Re: Radio Gear
« Reply #16 on: November 16, 2008, 07:18:38 pm »

I've always thought the way the frequencies are set-up is a bit nonsensical to me. After all, if I take my aeroplane out in a field, and start buzzing it about, there's absolutely nothing illegal about someone switching on a 35mhz TX in their home, perhaps to test another aeroplane on the bench and interfering with my radio outside.

Interesting that 40MHZ is not used in France, I wasn't aware of that. Pain in the bum, as I was hoping to get to one of their shows next year, not worth the bother now.
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Ghost in the shell

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Re: Radio Gear
« Reply #17 on: November 16, 2008, 07:20:56 pm »

I've always thought the way the frequencies are set-up is a bit nonsensical to me. After all, if I take my aeroplane out in a field, and start buzzing it about, there's absolutely nothing illegal about someone switching on a 35mhz TX in their home, perhaps to test another aeroplane on the bench and interfering with my radio outside.

Interesting that 40MHZ is not used in France, I wasn't aware of that. Pain in the bum, as I was hoping to get to one of their shows next year, not worth the bother now.
hence the introduction of 2.4
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Subculture

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Re: Radio Gear
« Reply #18 on: November 16, 2008, 07:25:37 pm »

Not much use to me!
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Ghost in the shell

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Re: Radio Gear
« Reply #19 on: November 16, 2008, 07:27:48 pm »

ask Roger in france about it, cos that one has caught me out.  &*(&(&^ french beauracracy!
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Sandy Calder

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Re: Radio Gear
« Reply #20 on: November 16, 2008, 07:50:47 pm »

I think France allocates the 41Mhz band.
There is a list of legal frequencies in the Robbe or Graupner catalogue at the crystal section.
There is some overlap so the higher end 40Mhz spots are legit.
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Mankster

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Re: Radio Gear
« Reply #21 on: November 16, 2008, 10:20:34 pm »

Interesting that 40MHZ is not used in France, I wasn't aware of that. Pain in the bum, as I was hoping to get to one of their shows next year, not worth the bother now.

France is on 41MHZ, my Shultze Rx claims to work on both 40/41 Mhz and my Tx generates both 40Mhz and 41Mhz frequencies so may be all you need would be a set of crystals.

dougal99

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Re: Radio Gear
« Reply #22 on: November 16, 2008, 10:30:25 pm »

Ghost (and anybody else interested)

You should be aware, as I found out in Dortmund last year, the lower 40Mhz frequencies are allocated to air use in Germany. Taking a look around the aircraft stands nearly all of the entry level RTF aircraft and Helicopters were 40Mhz. As I recall their frequency range was similar to that in the UK.

Don't you just love standards  {:-{

Doug
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cos918

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Re: Radio Gear
« Reply #23 on: November 16, 2008, 10:33:52 pm »

then there 49mhz which can be used in low power toys,but whats classed as low power

john
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Ghost in the shell

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Re: Radio Gear
« Reply #24 on: November 17, 2008, 05:03:14 am »

what happenned to European harmonisation?
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