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Author Topic: What to do with the Rx wire?  (Read 3974 times)

RipSlider

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What to do with the Rx wire?
« on: October 23, 2007, 07:41:58 pm »

Hello all.

Quick question: when your building a scale ( or in my case Scale-ish...) model, what are the normal methods of hiding the antenna?

Many thanks

Steve
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Colin Bishop

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Re: What to do with the Rx wire?
« Reply #1 on: October 23, 2007, 07:53:32 pm »

Do a search on "Aerial". There is quite a lot of advice in other threads such as this one for example.

http://www.modelboatmayhem.co.uk/forum/index.php?topic=2866.0

The best setup will depend on your particular model.
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John W E

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Re: What to do with the Rx wire?
« Reply #2 on: October 23, 2007, 08:06:13 pm »

hi there Steve, really I think it depends on the type of model you are building - whether it be a ship, boat, fishing trawler or whatever.   On some models,  you may have masts and may be able to run the antenna/aerial up the inside of the mast.  

On my Fairmile B I have ran the aerial along the deck edge close to the railings.  Yet to be painted and camouflaged in.

On WW2 HMS Ajax, the aerial actually makes up part of the ant-magnetic mine cable (degausser) that runs around the stern of the ship.

On the MTB, its actually coiled in a loop underneath the forward Carley Float; that may give you some ideas of how to camouflage them in.

Your question Steve, actually opens up another topic.

In the instructions that come with your RC set, It should state that your RX, receiver (aerial) should be stretched out as full length and vertical as possible.  

However, on some models, this is not practical.    The main thing is though - try and keep your aerial wire away from electrical noise making equipment in your model (noise making i.e. electric motors/relay switches/any item really that does or can produce a spark.)

As a footnote; the aerial wire that is wrapped around the Carley float on the MTB, this is a Futaba 6-channel receiver and I know for a fact that this model has well over a quarter of a mile range.

Just some food for thought for you my friend.

Aye
John e
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Mankster

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Re: What to do with the Rx wire?
« Reply #3 on: October 23, 2007, 08:37:34 pm »

My rx wire is always sealed inside the water tight part of my subs which are usually under water  ;). Don't have any problems with reception.

John W E

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Re: What to do with the Rx wire?
« Reply #4 on: October 23, 2007, 09:49:50 pm »

Mankster, hi there

Quick question - as they say.

What is the depth you can take your submarine too?

How far out into the Lake from yourself can you take the sub submerged?

Its an interesting thought receiving radio signals under water, as in past days, real submarines had to surface before they could transmit any messages.  I wonder if they still have to?

Anyone out there know....

or are we all too 'DEEP' into the topic  :) to receive signals.

aye
john e
bluebird
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Bryan Young

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Re: What to do with the Rx wire?
« Reply #5 on: October 23, 2007, 10:12:00 pm »

Well, as a starting point can I assume you will not be driving your ship or boat out of visual range? OK. In my earlier models when I knew nothing from nothing I followed the instructions religiously. Idiot me. Tynemouth lake is pretty big, but I have a couple of models where the aerial is stuck onto the inside of the (fibreglass) hull and have had no problems. This probably would,nt work with a metal hull. As most of my later models have removeable "tops", I have taken to fitting a length of brass wire down through the funnelnad into an electrical 2 way connector. The 2nd bit is a length of "springy" brass strip which (when the deck is slotted in) impinges on a permanently fitted brass tube wired to the receiver. No plugs. Straightforward connection. Works all the time.
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Ghost in the shell

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Re: What to do with the Rx wire?
« Reply #6 on: October 23, 2007, 11:27:54 pm »

I tend to run the antenna just under the deck in most cases or if its a yacht run it up the mast
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Roger in France

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Re: What to do with the Rx wire?
« Reply #7 on: October 24, 2007, 06:36:24 am »

BLURBIRD,

I read somewhere that modern submarines tow a very, very long aerial. I mean  kilometers long.

Roger in France.
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Faraday's Cage

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Re: What to do with the Rx wire?
« Reply #8 on: October 24, 2007, 09:24:10 am »

Just a point that if you run the rx inside a metal mast you will run the risk of reduced range due the mast shielding the aerial. Much better to solder the wire to the base of the mast and use the mast as an extension to the aerial.  Some say that the tx lead should be trimmed back to allow for the extra length  of the mast,  if so then measure aerial length from rx and mark on the back of the rx the full length, then if you take the rx out of the model at a late stage then you can restore aerial to its full length. Its best to try set up and range before cutting down through.

I prefer to get the aerial as high as possible so solder to an antenna on the superstructure if possible and use a 1mm plug and socket to assist when removed upper works.

Of course with 2.4ghz there's no problem as the aerials are only a couple in inches in length.

Terry.
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Colin Bishop

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Re: What to do with the Rx wire?
« Reply #9 on: October 24, 2007, 09:38:18 am »

Quote
I read somewhere that modern submarines tow a very, very long aerial. I mean  kilometers long.

Yes, that is for VLF (Very Low Frequency) communications which can penetrate the ocean so the sub doesn't have to come to the surface. However the date transmission rate is also very low so it's awkward to use. The more common means of communications is to send pre prepared compressed messages to and from satellites which entails the sub stiicking it's comms mast above the surface for a matter of seconds only.
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Bryan Young

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Re: What to do with the Rx wire?
« Reply #10 on: October 24, 2007, 06:29:27 pm »

Just a point that if you run the rx inside a metal mast you will run the risk of reduced range due the mast shielding the aerial. Much better to solder the wire to the base of the mast and use the mast as an extension to the aerial.  Some say that the tx lead should be trimmed back to allow for the extra length  of the mast,  if so then measure aerial length from rx and mark on the back of the rx the full length, then if you take the rx out of the model at a late stage then you can restore aerial to its full length. Its best to try set up and range before cutting down through.

I prefer to get the aerial as high as possible so solder to an antenna on the superstructure if possible and use a 1mm plug and socket to assist when removed upper works.

Of course with 2.4ghz there's no problem as the aerials are only a couple in inches in length.

Terry.
Running the aerial wire along one side of a non-metal hull works best if the aerial is close to (and above) the waterline. The water seems to act as a conductor. I came across this when "based" in Loch Long" and no TV signal could be obtained. But by just chucking the co-axe aerial wire into the water like a fishing line, a signal could be obtained. Perhaps the more electrically orientated members of the forum could expound? BY.
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Mankster

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Re: What to do with the Rx wire?
« Reply #11 on: October 24, 2007, 08:29:18 pm »

Mankster, hi there

Quick question - as they say.

What is the depth you can take your submarine too?

How far out into the Lake from yourself can you take the sub submerged?

Its an interesting thought receiving radio signals under water, as in past days, real submarines had to surface before they could transmit any messages.  I wonder if they still have to?

Anyone out there know....

or are we all too 'DEEP' into the topic  :) to receive signals.

aye
john e
bluebird

Hi I have taken asub down to 4.5m, the bottom of a diving pool, but its normally a max of 2meter and about 30 meters out, usually less. To be honest, I don't think I have ever run out of range when operating.

Sub can recieve signals at their max operating depth, though these are at very low frequencies and wavelengths in the hundreds of thousand meter range. Obviusey this is not 2 way communication as you need full on power station to power the transmiter. Low frequencies while able to penerate deeper can only transmit small amounts of information very slowly ( minutes for a few characters?). At about ten meters down sub can have 2 way communication. Obiouvsly this is sea water. Our 40mhz stuff is only good for a few centimeters at close range in salt water.

Voyager

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Re: What to do with the Rx wire?
« Reply #12 on: October 24, 2007, 08:30:10 pm »

I had a boat built by another modeller who soldered a lead to his scale aerial, it looked the part and should improve reception O0 I never had any reception troubles with this set up and i'll be building all my models like this from now on.
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Mankster

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Re: What to do with the Rx wire?
« Reply #13 on: October 24, 2007, 09:10:38 pm »

I had a boat built by another modeller who soldered a lead to his scale aerial, it looked the part and should improve reception O0 I never had any reception troubles with this set up and i'll be building all my models like this from now on.

Wouldn't that be altering the length of the reciever aerial? Optimally the reciever aerial for a 40mhz rx need to be about 8m or about 2m for 1/4 wave. So the Rx will have an inductor to make up for the lost length. Thats why they say not to alter the length of the RX wire in the manual.

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Re: What to do with the Rx wire?
« Reply #14 on: October 24, 2007, 10:09:08 pm »

It would, yes! The scale looking aerial had the replacement EXPO aerial soldered onto it, that then fed down inside the superstructure to a male plug, that fitted into the female plug which had the untouched receiver aerial attached to it. Like i said i never had any issues with reception, range was unaffected also.
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malcolmfrary

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Re: What to do with the Rx wire?
« Reply #15 on: October 25, 2007, 10:46:07 am »

Underwater reception in fresh water by all accounts is not a great problem.  Salt water is another story - reception falls off very rapidly.

With surface vessels, straightest and as vertical as possible is best, but run around the deck edge, large diameter coil mounted vertically, loose bundle, have all worked well for me as long as the aerial is well away from the motor and its wiring, the wiring is twisted to cancel interference as far as possible, the motor is supressed and not itself in a condition that is producing interference.
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Guy Bagley

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Re: What to do with the Rx wire?
« Reply #16 on: October 25, 2007, 12:39:00 pm »

Mankster, hi there

Quick question - as they say.

What is the depth you can take your submarine too?

How far out into the Lake from yourself can you take the sub submerged?

Its an interesting thought receiving radio signals under water, as in past days, real submarines had to surface before they could transmit any messages.  I wonder if they still have to?

Anyone out there know....

or are we all too 'DEEP' into the topic  :) to receive signals.

aye
john e
bluebird

Hi I have taken asub down to 4.5m, the bottom of a diving pool, but its normally a max of 2meter and about 30 meters out, usually less. To be honest, I don't think I have ever run out of range when operating.

Sub can recieve signals at their max operating depth, though these are at very low frequencies and wavelengths in the hundreds of thousand meter range. Obviusey this is not 2 way communication as you need full on power station to power the transmiter. Low frequencies while able to penerate deeper can only transmit small amounts of information very slowly ( minutes for a few characters?). At about ten meters down sub can have 2 way communication. Obiouvsly this is sea water. Our 40mhz stuff is only good for a few centimeters at close range in salt water.

we did the filming for the supermodels II programme on discovery, we had about 20 model subs in the water,everything from fantasy subs, to a engel typhoon, a nautilus, a delta  the late steve webbs chariot and others,   the pool we used is freshwater outdoors and man made.... the water is cleaned and filtered but on the filming day was non chlorinated..... we had 2 models sat on the bottom of the pool under full control, that was a depth of 22 feet, 

alot of us did not try it that far down though !
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