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  1. #1
    Join Date
    13th June 2017
    Location
    Colorado
    Posts
    2

    Quesstion for Communications Specialists users

    I'm wondering how those who use the Communications Specialists tracker units deal with the 20" transmitter antenna length. I'm considering using one in a nose cone mount but I'm not sure how to route the antenna. It seems to me that any configuration other than straight will decrease the range. Any suggestions welcome. Thanks.




    Bob
    (First post)


  2. #2
    Join Date
    31st May 2011
    Location
    San Diego, CA
    Posts
    2,553
    Quote Originally Posted by milehighrkts View Post
    I'm wondering how those who use the Communications Specialists tracker units deal with the 20" transmitter antenna length. I'm considering using one in a nose cone mount but I'm not sure how to route the antenna. It seems to me that any configuration other than straight will decrease the range. Any suggestions welcome. Thanks.




    Bob
    (First post)
    Welcome to the TRF Bob !

    In my use of the tracker i have just taped to the shock cord with electrical tape.

    Two of our greats have shared what they have done in the past .. CJ would drill small hole in nosecone bulkhead and feed the antenna through it ...then seal hole with a bit of putty.

    John Coker has 'arced' or softly bent the antenna around the interior wall of the nc..or loop around the antenna into a self holding circle I believe..YMMV he was not using that technique on a small nc

    Kenny

    Last edited by KenRico; 9th June 2018 at 04:51 AM.
    Fiesta Area Rocket Team - San Diego, CA

    TRA# 01113 L3, NAR # 38484 -DART, NAR Section #317
    GHS 2011 PB-X ROCstock XXXV GHS 2012 PB XI ROCstock XXXVII PBXII SPRINGFEST 2014 ROCstock XXXIX Oktoberfest 2014 LASTER Blaster ROCstock XL SPRINGFEST 2015 ROCstock XL1 ROCtober Oktoberfest 2015 LDRS XXXV ROCstock XLIII Holtville HAVOC Springfest 2017 Octoberfest 2017 --> Holtville HAVOC 2 :dark:

  3. #3
    Join Date
    9th May 2009
    Posts
    1,698
    I've wound the antenna on an older CSI tracker (which I replaced with more flexible wire) in a spiral form and put it inside a 38mm nose cone. I'm sure I degraded the range substantially but it's still more than adequate for most recoveries.

    I've also looped the antenna once when I couldn't use the hole in bulkhead technique that Kenny mentions.

    You've got a fair amount of margin with these units -- at least the older higher-power AT2B (I haven't tried the newer one yet.)

  4. #4
    Join Date
    13th June 2014
    Location
    Cocoa Beach, FL
    Posts
    3,842
    I have found that over time & use, my antenna has curled up quite a bit. Still find my rocket. & like KenRico, I just tape it to shock cord with electrical tape.
    Tim
    L3 NAR 98225

  5. #5
    Join Date
    25th January 2009
    Location
    Glennville, GA
    Posts
    17,997
    Quote Originally Posted by timbucktoo View Post
    I have found that over time & use, my antenna has curled up quite a bit. Still find my rocket. & like KenRico, I just tape it to shock cord with electrical tape.
    Me too.
    -----------------------
    Chuck Haislip
    NAR/Tripoli Level 3
    Formerly a Prefect of ICBM - TRA #60

    Level 1 - LOC Minie Magg; Level 2 - PR Broken Arrow;
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    2015 Ns for Year: 1315 Newtons
    My rockets usually fly naked. If they survive, they earn their paint.

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  6. #6
    Join Date
    23rd March 2011
    Location
    Goodyear, AZ
    Posts
    3,003
    Putting it in a N/C is not the best method, and you are right, anything less than straight will reduce it's effectiveness. One of the advantages of mounting it on the shock cord is when the rocket reaches apogee and separates, the signal dramatically increases, indicating the event.
    Just to clarify, don't tape the antenna, tape the button to the shock cord. I roll the antenna up with the button and put it in a nomex pouch, along with the drogue and shock cord.When the drogue deploys, the antenna straightens out.
    NAR 92675 L-3 TRA 14800 KG7IUN
    I may be getting older, but I refuse to grow up.

  7. #7
    Join Date
    10th July 2007
    Location
    Melbourne, Australia
    Posts
    1,496
    Not sure what altitude you are tracking to and what the frequency/power/data rate/many other factors are. As others have said, keep it straight for the most effective transmission.

    How much bend you can get away with depends on who much spare signal you have in your link budget. As long as you are above the minimum signal at the Rx for the decoding you will likely not notice any difference. You generally only see a difference on the edge of detection. Many factors reduce the signal and the ability of the system to maintain the link. Some ground testing might give you an inkling of what to expect if you curl/shorten/whatever to the Tx system. Probably won't give you an absolute limit on the distance but you could get a feel for the amount of degradation you can induce by curling etc.

    The best indication would probably be what others' flights have achieved and maintained the link.
    TRA 13430, Level 3

    "Everybody's simulation model is guilty until proven innocent" (Thomas H. Lawrence 1994)

  8. #8
    Join Date
    13th June 2017
    Location
    Colorado
    Posts
    2
    Thanks for all the replies and suggestions. For the foreseeable future, my altitude will remain under 20K. I like the ideas of running the antenna thru the bulkhead and also taping the button to the shock cord. I will also do some range testing with winding the antenna versus straight. The forum is THE place to go to learn how things are done. Thanks again.


    Bob


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