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  • To power the amplifier, you will also need:
    (1) DC adaptor 15v dc output
    (2) DC power Inserter.


    • This place died ? ;-(


      • Abandoned by all except me & you


        • Noooo Way ! Although it seems as if with all the good info given by abcd and others on other threads that some members think that the "dark" art of antenna building has been suitably enlightened.

          How wrong can you be ?


          • Its the way of the world, Im afraid... "nothing I build can be half as good as a commercial model, surely ? "
            When actually they often turn out BETTER.... and the art of making things seems to have died a death too :-(


            • It is not like this. Most have finally settled on an antenna which is good for them either DIY or commercial, and dont need this forum. Many have moved to other forums.


              • Definitely not dead!
                As you've said, it contains a lot of pertinent information that doesn't raise questions anymore.
                Thank you for your dedication to this subject!

                I've been an avid reader for the most part and since the forum has already some history, most of the problems are solved for me.
                Given that one can read and understand and doesn't need everything served on a platter.

                To keep on topic, I've put up my setup 2 weeks ago, with the antenna that came with the DVB-T card and today I plunged into making my first antenna. Tried already some wire collinears (without ground plane) and took a trip to a local store to buy a few parts.

                Settled on a 25x25cm aluminum plate for ground plane, centered on it 1 double female F type connector with a 68.8mm strip above and the original DVB-T card cable mounted in a male F connector on the underside.
                My reception is now a lot better and went up 10 fold on the number of planes (from 3 to 30) and 5-6 times the distance from 19nm to over 100nm. The antenna is still mounted outside my window, facing north so I only get about 180 degrees of view until I will mount it on the house, with a full sky view.
                I am waiting on some 8dB/1GHz cable and a 20dB amplifyer to be able to have a long run of cable to the roof.
                In the meantime I plan to build a spider and cantenna to test them compared to my current 25cm sqare groundplane.



                • Which design did you use CCZ ? Looking at a wire with coils next myself...


                  • Sorry, can't post links yet but google adsb sprut and it will take you to that page.
                    Then I have also tried the 2 small coils with 5/8 center, ripped from a wifi build, adapted for 1090MHz. Can't find the design anymore but I'm pretty sure both were discussed in this thread.
                    Played a little bit with a J pole today, probably still needs tuning since the results were worse than the original DVB-T stick antenna.

                    Both wires worked ok but spotted only planes above antenna and close ones on the ground (10-15nm). They both seemed very directional to me.

                    I have just mounted a cantenna and am comparing it to the 25cm flattenna i did before and it seems I gained a few nm, results are almost identical.

                    Grey background is cantenna, turquise is flattenna. Each circle is 50nm.
                    Please disregard the darker center, that's another RPI receiver sitting in a window that I forgot to take out of the pics.
                    Attached Files
                    Last edited by ccz; 2016-07-24, 22:26.


                    • My experience of wire collinears with stubs (hairpins) and coils:
                      I have tried a large number of wire collinears of different designs from internet as well as my own simulations.
                      Most design on internet, and also by my own simulation, show high gain, SWR<1.5.
                      When I built these and tried, ALL proved far inferior than 1/4 wavelength ground plane (Spider, Cantenna, Platetenna etc etc).
                      The designs are faulty, so are simulation software results!


                      • abcd567 why do you have such a downer on coco's? i know from posts else where you try to do everything as cheap as possible (with good reason) but when you are doing that you can't take the velocity factor of the cable as what they tell you, you have to work it out, i hate to think how far out you could be on section lengths. as for the velocity factor i know you have the equipment to work it out (think stub filter and the length of the piece of coax)

                        also did you solder any of your coco's together ? On the VNA you wouldn't believe how much they change in just moving them around.

                        you are right in the fact that a lot of the designs are floored (to simplistic, assumed values), but if you are accurate and don't rely on pushed together connections and know the velocity factor of your cable they are quite good.

                        All the FR24 aerials are coco's for example, also they are pretty easy to copy

                        Are spiders easier to make right first go yes, but there is nothing wrong with coco's. I have made plenty and all of them comparable to the spiders i have made.

                        Yes i do have equipment (VNA) available to me to check them, but any i have made and posted here (lord only know what page) i made a point of not adjusting them on it, what be the point if others couldn't make them.
                        Last edited by SpaxmoidJAm; 2016-07-25, 20:32. Reason: trieed to sort, my grammar and english out


                        • Originally posted by SpaxmoidJAm View Post
                          abcd567 why do you have such a downer on coco's?
                          My remarks in my last post were about "wire collinears", not about CoCo. Please see the very first sentece which I quote below:

                          "My experience of wire collinears with stubs (hairpins) and coils"

                          As regards professional antennas (wire collinear and coco), their prototypes as well as production units are tested and tuned with the help of test equipment, such as a VNA, and that is why these perform so good. How many of adsb hobbyists have acces to such equipment and have technical know how to use these test equipment properly?

                          The coco requires as a first step to use a coax of known VF , hence many hobyist who dont know or use correct VF end up in poor antenna. They have no way to find out what went wrong.

                          The wire collinears dont have any insulation & braid, just naked wire. There is no problem of using correct VF like coco, but still these cannot be made properly tuned without test equipment. Reason: their tuning is extremely sensetive to dimensions. Few mm error in dimension of a straight element, stub, or coil knocks down these antennas from good to poor.

                          To summerizs, Coco & Wire Collinears are both very good antennas if made & tuned by PROFESSIONALS, and a very disappointing experience if made by a hobbyist without test and tuning equipment & without enough technical know how.
                          Last edited by abcd567; 2016-07-25, 23:07.


                          • @SpaxmoidJAm

                            The latest case of poor Coco known to me is the one built by hobbyist FR24-BB8, who used a Coax of known VF (coax data from manufacturer's site), and is very skillful & crafty, but still he failed in making a good coco. Please click here to see his concluding remarks after making several versions of Coco:

                            Just to clarify, from my tests so far, ive got the best results with a spider.

                            You can also read his earlier posts in that thread about details of his attempts to make a Coco.
                            Last edited by abcd567; 2016-07-26, 03:15.


                            • Tried today SpaxmoidJAm Coco from the link posted above and realized that my RG6 cable that I had is copper covered steel center and steel braid.
                              Everything is fully magnetic. That's what you get for $0.05/meter. Considering the poor quality of the cable, it's a miracle I managed to do it, please read further.

                              Steel means that I couldn't solder the 5 Coco pieces together so I cut 5 more with the top one 6cm longer.
                              I searched the cable code and found a page that stated 85% velocity factor for this cable. I doubted that and still don't think it to be correct but assumed that value nevertheless. So my elements are 117mm long with about 3cm longer center wire on each side. Top element has 58mm whip on one side and 3cm for connecting to rest of Coco on the other side. Whip is not shorted and stripped to bare wire. Elements are force pushed into each other for about 25-30mm center wire length with tape insulator between them. Classic simple coco procedure.
                              Attached at the end about 30cm of the same wire, same connection style to coco and F connector on the other side continued to original cable of DVB-T (another 60cm).

                              Just installed it and from the looks of it reception is on par with my cantenna. Comparative number of planes, almost same distances (too soon to be sure) but I seem to get a lot more position fixes.
                              Will let it run for 24-48hours and report back.


                              • good to see you weren't put off from trying it. Experimenting is half the fun.

                                It was from in this mammoth series of posts that with a odd number of elements is was better to short the end (i think that was from simulations rather than practical experiments). Its been so long since i have actually made one, but i did have most success with even numbers especially if you go to eight elements.

                                Actually about to start making a directional yagi antenna just rounding up the parts, i will take pictures along the way and post them here when i am done.