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    Preventing interference

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    david f
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    Preventing interference

    Post  david f on Wed Mar 30, 2011 12:17 pm

    Very useful link , I think. (I am indebted to Andy L (Subculture) and Model Boat Mayhem for this.}

    http://www.kronosrobotics.com/an142/GAN142.shtml


    Last edited by david f on Sun Feb 12, 2012 11:03 am; edited 2 times in total

    david f
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    Re: Preventing interference

    Post  david f on Wed Mar 30, 2011 12:22 pm

    Yet another use for tin sheet (coated steel of course.) is to solder up a little receiver screen. I have found that this helps.

    Interference is a real problem (and preventing it a black art!) in model submarines because everything is so packed in. (Well it is in my models!)

    Richard(Admin)
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    Re: Preventing interference

    Post  Richard(Admin) on Wed Mar 30, 2011 12:25 pm

    Could that be a variation on the Faraday Cage?


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    acrowot (Geof)

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    Re: Preventing interference

    Post  acrowot (Geof) on Wed Mar 30, 2011 2:14 pm

    Hi all

    I have found interference is my biggest bug bear in my electric flight aircraft some running at 1000 watts input power now solved with 2.4 ghz (can not use in model submarines)
    But before 2.4 interference was a big problem found there was never one solution fixes all problems set up an aircraft one way perfects set up another same way same make model motor speed control receiver you could have problems.
    But here is a list of things you could try that I have found out over many years

    1 keep receiver as far away from the motor speed control and stand alone Becs as possible and try not to run the aerial past these items on one of my ducted fans I ran the aerial down the wing away from the motor which stopped all the problems

    2 I have found it can help wrapping the receiver in tin foil with the aerial coming straight out (put insulating tape across the servo plugs so the tin foil does not short the plugs if a bare wire is present) this I do as standard practice in all my aircraft on 35 mhz

    3 change frequencies I fly on 35 mhz channel 61 my friend fly’s on 35mhz channel 75 I can fly at our field and have problems my friend has no problems change mine to channel 75 problem solved
    problem can be reverse at a different location I have no problem friend has problems
    So location and weather can have a big impact on interference

    4 I also use ferrite rings were you wrap the servo lead round and round the ring just before it enters the receiver I always put one on the speed control and servos if necessary http://www.sloughrc.com/default.asp?WPG=SRCM_HomePage1&PageNumber=1&s=c:0,c:070,c:070-120,c:070-120-110

    5 uses a dual conversion receiver if you can this can make a big difference
    due to better filtering of the signal

    6 Becs built into speed controls or stand alone Becs specially switching becs can be a source of interference I found hobby wings stand alone Becs and speed controls from giantcod to give me very little problems
    Best bec I have used is a caged one about £15 (I will add a link when I get home)

    6 if i am using a brushed motor i always use the 3 mfa cappacitor pack on the back of the motor

    7 try not to lenghten the speed control to battery wires brushed or brushless i have had a lot of problems doing this a freind had a spitfire with major interference then i found out the wires had been lengthend i put them back to the right lenght problem solved

    8 one other thing is do not shorten or lenghten the receiver arial keep the same lenght were ever posssible

    Hope this may be of help if I think of any thing else I will add it here

    Take care all the best geof


    Last edited by acrowot (Geof) on Wed Mar 30, 2011 2:27 pm; edited 1 time in total

    Richard(Admin)
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    Re: Preventing interference

    Post  Richard(Admin) on Wed Mar 30, 2011 2:19 pm

    That's a very interesting reply, thanks Geof(is it one 'f' or two?)

    I remember using ferrite rings back in my days of naughty radio(27Mhz SSB and 6.6Mhz)never thought to apply them to radio control...well worth considering.


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    acrowot (Geof)

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    Re: Preventing interference

    Post  acrowot (Geof) on Wed Mar 30, 2011 2:38 pm

    Hi Richard

    spell Geof as you like I spell it with one f most people spell it with 2
    with interference you have to try every thing you can thinks of with aircraft what goes up must come down interference will bring it down with no problem sometime its like some one has switched on your channel and you have no control at all a very dangerous situation to be in

    just to let you know I have just added a couple of other points to my last post

    Nice to her from you Geof

    Richard(Admin)
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    Re: Preventing interference

    Post  Richard(Admin) on Wed Mar 30, 2011 2:49 pm

    I once gave my name to a police officer(back in my youth, you understand!)as Smiff with two F's...he wrote it down as well. Never did hear anything about that...

    Anyway, I've always been lucky(touching wood)with interference to my radio gear in my boats, up until now I've never suffered from it. My little Kilo has the radio gear really stuffed into the wtc, the aerial wire is wrapped around the rx and the esc, and the motor lays between rx and the esc one end and the two servos the other end, and there's never been as much as a twitch out of place.

    Some to suffer from it very badly, some seem to never have a twitch...it's one of those peculiarities of the hobby, I guess.

    Still, a very interesting post Geoff...thanks for your input.


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    david f
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    Re: Preventing interference

    Post  david f on Wed Mar 30, 2011 4:37 pm

    A very interesting reply from Geof.

    It sounds like electric aircraft have a lot in common. (And they have even bigger currents which must make things worse.)

    People now have a very good list to work through - and that often seems to be the only way to do it.

    Subs and aerials are a different case from aircraft, perhaps. Potentially more difficult.

    I wrap the aerial around a piece of ply with the loops going back in the opposite direction. It is still not perfect and "way out in the pond" the signal fades. Usually putting the TX aerial vertical sorts it.

    It would be nice to know if anyone has a better method.

    I think we talked about this on the F***b**k site.

    Uncle Nigel had a solution but never posted it.

    Maybe he would be prepared to now on our own comfy site with leather armchairs!

    Richard(Admin)
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    Re: Preventing interference

    Post  Richard(Admin) on Wed Mar 30, 2011 4:49 pm

    In my little Kilo, the aerial wire is just(literally)tied around the rx and the esc in a big loop, with the motor right up against it...so far, so good.

    The Patrick Henry had the aerial wire just coiled up and tucked under the battery, Onondaga had the aerial outside the radio box and wrapped around itself, as did my U boat and my X craft.

    The Biber will have the aerial wire wrapped around itself and tucked away wherever it fits...I normally tie it all up in a trucker's knot and stuff it where it fits.

    If I remember correctly, you used to be able to buy a coiled aerial, around a couple of inches long, which was almost like a pcb board, you simply chopped off the main part of your aerial wire, soldered it to the end of the board, and away you went. I did have one once, fitted to my American .65cu.in engined 3 point hydro...it seemed to be ok as far as I can remember.


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    acrowot (Geof)

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    Re: Preventing interference

    Post  acrowot (Geof) on Thu Mar 31, 2011 12:17 am

    its funny how there is no hard and fast rule with interference but does keep the grey matter at bay at least with aircraft we have the space to move things about
    i have been told that you can wrap the areial around a peice of ply and will work never tryed it as i feel the range would be reduced.
    here are to links to stand alone ubecs that i use
    http://www.giantcod.co.uk/hobbywing-575a-ubec-lipoly-p-402620.html
    http://www.giantcod.co.uk/hobbywing-3amp-ubec-p-402342.html

    all the best geoff

    david f
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    Re: Preventing interference

    Post  david f on Fri Apr 01, 2011 11:54 am

    I have tried stringing the aerial around the WTC also but it gives inconsistent results in different models.

    The plywood former approach may sacrifice some range but at least it is consistent and stows in most WTCs.

    What we need is a little aerial unit for 40Mhz?

    david f
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    Re: Preventing interference

    Post  david f on Sat Sep 15, 2012 9:22 am

    I have had a long run problem with interference in at least 2 of my subs - Holland and Resurgam.

    At the last Haydock Park show I couldn't control the Holland even in a small pond. The usual way it showed itself was poor or no control of the speed controller.

    I have tried everything - new ESCs , ferrite rings everywhere etc. etc.

    The problem was solved finally by chucking out my single conversion receivers and going for DUAL conversion ones.

    If you want proof - have a look at the video of the Holland at Barrow.

    Sad to say that I have found this out just as it becomes more difficult to obtain 40Mhz receivers and crystals,in particular!

    David

    Hermann

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    Location: at home, near Bremen (Germany)

    Re: Preventing interference

    Post  Hermann on Fri Sep 28, 2012 6:50 am

    Hello again,

    please let me give also some remarks concerning receiving aerials in submarine models.

    In principle and independent of the model category routing of the receiving aerial has a major influence of the receiving quality and with bad routing the usable control range may be reduced dramatically ( just like on the transmitter side when the transmitter antenna is not expanded and only a stub).

    But which kind of routing is poor an which is most useful? To receive the control signal the receiver needs a signal voltage at its input, this signal voltage develops between the aerial wire as one pole and the residual wiring such as supply cable, servo cables, speed controler cable etc. ; that residual wiring serves as a "counterweight" to the aerial, the second pole. A voltage means always a difference between the electrical potentials of two poles, in this case the voltage occurs between the aerial wire and the "counterweight" given by the residual wiring. To pick up as much radio frequency energy of the signal from the electromagnetic field, aerial wire and counterweigth should be layed out as far as possible apart from each other. They shouldn't be routed together. You can explain this circumstance by yourself when you remember that the measurement unit for the electric field stregth is defined as Volt per metre (V/m), so if you have a certain fied strength at the location of your model you will get more voltage if you increase the distance between aerial and counterweight (well, when submerged the voltages will be very low, in the range of microvolts). Of course separating aerial wire from the other cabling may be problematic in some cases, especially for small models, but in general it is useful to follow that rule.

    It is not necessary to route the aerial inside the pressure hull, the aerial may be also in the flooded aeria. If your pressure hull contains additional conductive structures (e.g. thread rods of a technics rack) it is important to keep the aerial on distance to these elements and put it outside.

    Of course it is also important to have an effective suppression of interference generated by sources within the model (e.g. brush type motors or switchmode voltage regulators for power supply). For good signal reception a good signal to noise ratio is essential. That means if the field strength of the signal is low (due to attenuation in water) the noise level must be consequently low to maintain a sufficient good signal to noise ratio.

    Kind regards
    Hermann

    Giovanni LiCalsi

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    Aerial

    Post  Giovanni LiCalsi on Fri Sep 28, 2012 7:48 am

    Hermann,
    This is good information.
    I will be building a 1/12th scale 1898 USS Holland submarine fabricated out of copper, brass, bronze and stainless steel. I will need to route the aerial outside of the hull structure.
    I am also planning an all-metal 1/48th scale Skipjack submarine.

    Greetings,
    Giovanni


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