How To Adapt The 'New' 2.4gHz Gear To R/C Submarines

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  • coryhenry
    replied
    I took the stock receiver and removed one antenna and replaced with a long coax as detailed in the instructions. It worked perfectly. Here is the link to the transmitter and receiver.

    https://hobbyking.com/en_us/turnigy-...-receiver.html

    Here is the type of cable I used;
    ​​​​​​Mini RG59 Coax Cable - BC- Black - Per FT SKU: 80-523-910 BK from showmecables

    The wire was a little thicker than I thought but worked very well.
    Last edited by coryhenry; 10-05-2021, 01:50 PM.

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  • redboat219
    replied
    Cory,

    Are you using a stock 2.4gHz rx or one that has been modifified?

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  • coryhenry
    replied
    Well, I have been having issues with my 75mHz Kilo and it prevented me from running for multiple meets. I decided to try 2.4 and I have to say I really like it. I have no issues with control from very long distances and I even get control from 20m away a couple of centimeters under the surface. The boat has a slightly positive buoyancy anyway so I think its an ideal solution.

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  • Davidh
    replied
    Hi David and Bob.

    Yes I admit The Tx was right on the side of the pool and probably about half a meter from the cylinder. I then pushed the cylinder half a meter down, tip of antenna in a piece of foam floating. Walked to other side of pool and tested, Works really well, Thankyou David for writing up the instructions. Bob I remember you mentioned a while back that when your boat dips beneath PD you hardly notice and have solid reception. I am really looking forward to seeing how this runs in U 23 early next year and excited about the extra functionality of the receiver, ( dialing in failsafe functions).

    Dave H

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  • RCSubGuy
    replied
    The air/water interface is the biggest challenge. High frequency "skips" off the surface. Get more than a few dozen feet away and I'll bet you don't get more than an inch of water penetration (if that).

    I set up my high frequency boats to automatically command 1/3 throttle and full rise on planes with loss of signal. In most runs if I accidentally dip the antenna, I don't even notice as the boat simply rises until the antenna pops out again.

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  • He Who Shall Not Be Named
    replied
    Originally posted by Davidh
    Hello all,

    I spent yesterday afternoon, desoldering a 2.4 ghz receiver , and slowly followed the above instructions to attach a new longer lead and make the small antenna at the end of the coax. Put it inside a cylinder with a servo and small battery and antenna coming out endcap sealed, and then tested it. IT WORKS PERFECTLY.

    But, I then pushed the antenna down underwater to a depth of about 50 mm and it kept working. Below that and there was no reception. I raised the antenna once again to within the 50 mm range and my tx beeped and the servo started moving again.

    Then this morning I used a standard 2.4 ghz rx of the same model ( with no modification ) and did the same thing, just to check that it would not work at all with the cylinder slightly below water level. Well it worked fine to a depth of 50mm.

    I am very surprised, but delighted at the same time. I intend to run my upcoming U -23 with 2.4 Ghz

    I thought 2.4ghz does not work with an antenna underwater? Have I missed something?

    David H
    The inverse square law is your friend. How close was the transmitter antenna to the receiver antenna during this 'test'? Did you try it with at leas a 50' cross-range between the two?

    David

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  • Davidh
    replied
    Hello all,

    I spent yesterday afternoon, desoldering a 2.4 ghz receiver , and slowly followed the above instructions to attach a new longer lead and make the small antenna at the end of the coax. Put it inside a cylinder with a servo and small battery and antenna coming out endcap sealed, and then tested it. IT WORKS PERFECTLY.

    But, I then pushed the antenna down underwater to a depth of about 50 mm and it kept working. Below that and there was no reception. I raised the antenna once again to within the 50 mm range and my tx beeped and the servo started moving again.

    Then this morning I used a standard 2.4 ghz rx of the same model ( with no modification ) and did the same thing, just to check that it would not work at all with the cylinder slightly below water level. Well it worked fine to a depth of 50mm.

    I am very surprised, but delighted at the same time. I intend to run my upcoming U -23 with 2.4 Ghz

    I thought 2.4ghz does not work with an antenna underwater? Have I missed something?

    David H

    Leave a comment:


  • SubDude
    replied
    I have found that personally I like the simplicity of 2.4 GHz and radio programming capability. PD is fine for me.

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  • SteveNeill
    replied
    Thanks David for making simple sense of this. My radios are slowly dieing and it's time I went 2.4 ghz.

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  • redboat219
    replied
    Click image for larger version

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  • He Who Shall Not Be Named
    replied
    Originally posted by redboat219
    I read somewhere that if you are using a 2.4 ghz system with a brushed motor drive you don't need to install noise suppression capacitors. Is this true?
    Don't know. But, why take the chance of finding out in the middle of the lake while in submerged trim. Two ounces of prevention... and all that happy horse-****.

    A truly Dumb question!

    Why not get underway with a leaking WTC? Why bother with post-mission checks? Why not yank out that transmitter antenna in the middle of a lightning storm? Why not make moves on Harley Quinn in front of Mr. J?

    Dumb...DUMB.. DUMB!

    David

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  • redboat219
    replied
    I read somewhere that if you are using a 2.4 ghz system with a brushed motor drive you don't need to install noise suppression capacitors. Is this true?

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  • He Who Shall Not Be Named
    replied
    You got it right. And that antenna exposure at the up-in-the-air end of coax core (antenna) should be exactly 1.25" in length. Which makes it a full-wave 2.4gHz antenna.

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    David

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  • Davidh
    replied
    Hello David and all,

    I have been reading all the comments and posts regarding adding an extension to a 2.4 ghz antenna. The questions that I am going to be asking have already been covered, I am asking them for the sake of clarity and to make sure that I am on the right track. I have a receiver , a Turnigy iA6C. It has twin antennas.

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    It does not have IPX connectors. I took it apart and found this.

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    I presume that the first blob of solder is the shield pad and the second is the antenna pad. Does that look right? I have done a drawing to clarify my thinking.


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    So in a nutshell at the receiver end it is about grounding the outer sheath / shield and connecting the inner core cable to the antenna connection and then exposing the other end however far at precisely the right length of exposed core?

    Thanks for the clarification

    Davidh

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  • Bob Gato
    replied
    Well that's not going to work...my friend... it's model submarines and you are in over your head..I strongly suggest that you reread the many threads on extending 2.4 antennas.

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