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  • Originally posted by 1090 MHz View Post
    Remember the secret antenna design photos I showed you... it had a sorted top element.
    No offense - but now we have secret antennas on an open forum. Interesting.
    Here in Africa we need every trick in the book because we have very few aircraft and the distances between stations are long.
    Why not share the "secret".
    I have built just about every antenna design I could find - Some slightly better than others.
    Last edited by SBSer; 2013-12-10, 08:05.

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    • Originally posted by SBSer View Post
      No offense - but now we have secret antennas on an open forum. Interesting.
      Here in Africa we need every trick in the book because we have very few aircraft and the distances between stations are long.
      Why not share the "secret".
      I have built just about every antenna design I could find - Some slightly better than others.
      The "secret" antenna of 1090MHz is no more a secret, as I have built it and done a trial run, and then have posted it's details in this forum few weeks ago. I am again posting those pictures of "secret" antenna for your reference. Thanks to 1090MHz.
      DSC02846R.jpg .... DSC02845R.jpg
      Last edited by abcd567; 2013-12-10, 10:22.

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      • You're missing the Umbrella choke balun ... it might work even better with it. As for the 'secret' photos... email me at radar@ads-b.ca
        www.ADS-B.ca

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        • Thank you ! ! I have built those - up to 8 elements BUT without the "trick" at the top end.

          Will give it a shot

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          • Originally posted by 1090 MHz View Post
            You're missing the Umbrella choke balun ... it might work even better with it. As for the 'secret' photos... email me at radar@ads-b.ca
            I am missing the Umbrella choke balun intentionally. I want to test one thing at a time. This way it is easier, and more concluding results are obtained ...as they say...don't try to eat the whole of your elephant at once. Cut it into slices and eat a slice at a time....

            Determining the effect of De-coupler Sleeve / Balun will be my next step.

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            • Originally posted by SBSer View Post
              Thank you ! ! I have built those - up to 8 elements BUT without the "trick" at the top end.

              Will give it a shot
              In case you are using an in-Line Amplifier, the short at CoCo's top will cause short-circuiting your DC Power Supply, and may fry your power supply, or power injector, or amplifier, or all

              In case of Amplifier, insert a DC blocking capacitor between Amplifier and CoCo. See 3 pictures below which show how I have done that. I learned this lesson the hard way, after frying my power injector's inductor

              DSC02842R.jpg DSC02843R.jpg DSC02844R.jpg

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              • Thank for the warning but already done for testing other DC shorted designs like Slim Jim etc

                See http://www.m0ukd.com/Calculators/Slim_Jim/ - works amazingly well for such a compact design in 1090 MHz!!!
                Last edited by speedbird1960; 2013-12-10, 22:10. Reason: POST APPROVED AS ITS NOT SPAM.

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                • Originally posted by abcd567 View Post
                  In case you are using an in-Line Amplifier, the short at CoCo's top will cause short-circuiting your DC Power Supply, and may fry your power supply, or power injector, or amplifier, or all

                  In case of Amplifier, insert a DC blocking capacitor between Amplifier and CoCo. See 3 pictures below which show how I have done that. I learned this lesson the hard way, after frying my power injector's inductor

                  [ATTACH=CONFIG]3035[/ATTACH] [ATTACH=CONFIG]3034[/ATTACH] [ATTACH=CONFIG]3033[/ATTACH]
                  What is required to connect the DC power supply to the Power injector? I'm expecting my dongle tomorrow so should finally get some testing done. I will probably start out with the stock Antenna and get all the software working before trying any other Antenna.

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                  • Originally posted by mickopla View Post
                    What is required to connect the DC power supply to the Power injector? I'm expecting my dongle tomorrow so should finally get some testing done. I will probably start out with the stock Antenna and get all the software working before trying any other Antenna.
                    It all depends on the dc connection arrangement on your inserter and on your dc powe adaptor.

                    My inserter has an F-female connector and the dc adaptor has a barrel male pin. They dont match, so I prepared a pigtail from a small piece of coaxial with solderable braid (copper or tinned copper). On one end of pigtail, I fitted screw-on F-male connector, and on the other end soldered a dc barrel female socket. See photos of dc barrel pin & socket below .

                    Alternatively, you can cut the male barrel pin from adapter wire and solder adaptor dc wire to coaxial pigtail's center wire & braid. Check with voltmeter to ensure that you have connected +ve wire of dc adaptor to center wire & -ve wire to shield of coaxial pigtail.


                    Sent from my N762 using Tapatalk 2
                    Last edited by abcd567; 2013-12-11, 00:33.

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                    • This is a repeat of info already in this thread ...

                      Have a look at ebay.co.uk for "line power inserter" (ones like ebay item 161044085914) - then have a look at your local ebay for something similar if you don't want to construct it.

                      You can use two of these if you have a short circuit antenna (coco with a loop at the top), one yo inject power into the line to power the amp, then a second between the amp and the antenna (run this one un=powered) to remove the DC power still on the line.

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                      • Comparison of 2 CoCos:
                        1) Un-shorted top with a 1/4 wave whip.
                        2) Shorted top with no whip.

                        Conclusion: {CoCo with Shorted Top, No Whip} has a BETTER RANGE than {CoCo with un-shorted top and a 1/4 wave whip}, under both conditions i.e. no-amplifier & with-amplifier.
                        See Screen shots below:


                        Without Amplifier
                        CoCo-3-and-half+quarter-whip.jpg CoCo-3-and-half+shorted-top.jpg


                        With Amplifier
                        CoCo-three-and-half+quarter-whip+Amplifier.jpg CoCo-three-and-half+Amplifier.jpg
                        Last edited by abcd567; 2013-12-11, 18:23.

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                        • Originally posted by abcd567 View Post
                          Comparison of 2 CoCos:
                          1) Un-shorted top with a 1/4 wave whip.
                          2) Shorted top with no whip.

                          Conclusion: {CoCo with Shorted Top, No Whip} has a BETTER RANGE than {CoCo with un-shorted top and a 1/4 wave whip}, under both conditions i.e. no-amplifier & with-amplifier.
                          See Screen shots below:
                          Thanks for those detailed charts,
                          That's almost identicle to a collinear antenna I posted on another thread (http://forum.flightradar24.com/threa...linear-antenna) with a video (not mine) on how to construct it but without the 1/4 wave at the top- something I have since added but have not yet been able to test outdoors as I dont have any weatherproof tubing or conduit (strange thing to say for a former electrician).
                          I made it 8 elements. Does the number of elements make any real discernable difference? ( I may have been a sparky but antenna theory was not one of my strong points). Thanks in advance for anyone who may be able to answer.

                          Regards,
                          Gregg
                          Last edited by fungus; 2013-12-11, 21:55.
                          YSSY2/T-YSSY4 [SBS-1 Basestation w/- SSE-1090 SJ Mk2 Antenna (Thanks Delcomp) ] [Uniden UBCD996T w/- 16 element Wideband Discone VHF/UHF Antenna, and tuned 108MHz-137MHz Airband Antenna] [Trialing a home-brew 1090MHz collinear antenna]

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                          • Edited. Please see edited post below.
                            Last edited by abcd567; 2013-12-11, 23:00.

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                            • How about putting the 200pF capacitor where the shorting link is at the top of the coco?
                              (Simpler)

                              Sent from my GT-P5110 using Tapatalk

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                              • Originally posted by peterhr View Post
                                How about putting the 200pF capacitor where the shorting link is at the top of the coco?
                                (Simpler)

                                Sent from my GT-P5110 using Tapatalk
                                Seems a good idea. Let us give it a try.

                                Sent from my N762 using Tapatalk 2

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