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  • Originally posted by 1090 MHz View Post
    I went a bit over the top when I had that tower built but now I'm glad I did... it's a heavy duty reinforced design, and has an ice load rating, so it can take quite a large load.
    [ATTACH=CONFIG]3108[/ATTACH]
    You are wise & foresighted.

    Originally posted by 1090 MHz View Post
    ....
    . As for my birch tree it didn't do so well ... LOL!
    [ATTACH=CONFIG]3109[/ATTACH]
    Ahhh! The poor birch tree
    Many birch trees along our local road met the same fate.

    Sent from my N762 using Tapatalk 2
    Last edited by abcd567; 2013-12-24, 00:51.

    Comment


    • Originally posted by mickopla View Post
      ......With regards cable runs would reducing length from 30ft to 15ft make any noticeable difference to coverage with a whipped Coco that uses an amp?

      Mike
      Mike, at 1090 MHz, the attenuation (loss of signal) in normal RG6 coaxial cable used in homes is about 6.5 to 6.8 dB per 100 feet (depending on quality/manufacturer). Taking worst case of 6.8 dB/100feet, the attenuation for extra 15 feet will be 6.8x15/100 = 1 dB, which your 20dB amplifier will cover, and you should not notice any difference in coverage.


      Sent from my N762 using Tapatalk 2
      Last edited by abcd567; 2013-12-24, 00:43.

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      • Originally posted by abcd567 View Post
        MERRY CHRISTMAS & HAPPY NEW YEAR
        Same to you and your family... I see Santa bringing you some UHF radios on a very slow sleigh from China !
        www.ADS-B.ca

        Comment


        • Originally posted by 1090 MHz View Post
          Same to you and your family... I see Santa bringing you some UHF radios on a very slow sleigh from China !
          Hahaha...Santa was scheduled to deliver between 16 & 23 Dec, but it seems I will not get it on Chistmas, maybe new year's gift.

          Sent from my N762 using Tapatalk 2

          Comment


          • Originally posted by abcd567 View Post
            Hahaha...Santa was scheduled to deliver between 16 & 23 Dec, but it seems I will not get it on Chistmas, maybe new year's gift.
            Did they give you any tracking number?
            www.ADS-B.ca

            Comment


            • Originally posted by 1090 MHz View Post
              Did they give you any tracking number?
              Yes, but it is not full tracking. It tracks only up to dispatch. Anyway since their declared delivery date expired only today, and since I have lost my 'impulsive' interest in these radios, I am not anxious to receive then quickly.

              Sent from my N762 using Tapatalk 2
              Last edited by abcd567; 2013-12-24, 01:33.

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              • Originally posted by mickopla View Post
                Same to you abcd567

                I made a half wave dipole today and was impressed with the results. Max distance was 320km this without any amp. It does have a very short cable run but still impressive........

                Mike
                Half wave dipole has the beauty that its impedance (73 ohm) matches with coaxial cable's impedance (75 ohm) and DVB-T receiver's impedance (also 75 ohms). Another advantage is that there is no velocity factor involved in calculating length, hence no assumptions, and it can be cut to accurately 13.8 cm total height, tip-to-tip. That is why one can get a gain almost equal to it's theoretical gain of 2.15dBi. On the other hand, although 4-element CoCo has a theretical gain of 5 dBi, the CoCo cut to wrong dimensions (due to assumption of velocity factor), may actually have much less than 5 dBi, even less than 2 dBi of 1/2 wave dipole.


                Franklin half-over-half diploe has theoretical gain of 5 dBi and can be cut to precise dimensions like half wave dipole, but has a very high impedance (4000 ohms) and if proper matching method is not used, gives a low gain & poor coverage. I have covered loss of gain in Franklin by using 2 amplifiers, and got a very good coverage. But without amplifier and without impedance matching, Franklin gives poor performance.With Franklin, you must have at least one: either impedance matching or amplifier.


                Sent from my N762 using Tapatalk 2
                Last edited by abcd567; 2013-12-24, 04:17.

                Comment


                • For 'abcd567 and Rooster'.. Interesting article from 'AUSTRALIAN ANTARCTIC MAGAZINE"..

                  Moon bounce from Antarctica
                  Amateur radio operator Craig Hayhow has used the moon to bounce
                  a radio signal 742 000 km, from Mawson station in Antarctica to
                  Cornwall in England.
                  Proving the feat was no accident, two nights
                  later he performed another ‘moon bounce’ to
                  communicate with radio operators in Sweden
                  and New Zealand.
                  ‘The “Holy Grail” for many serious amateur radio
                  operators is bouncing a radio signal off the
                  moon and reflecting it back to Earth to have a
                  conversation with another station on the other
                  side of the world,’ Craig says.
                  ‘The technical challenges are immense, but
                  with modern high speed computers and
                  sophisticated software, it has become a lot
                  easier in recent years.’
                  Craig, who is wintering at Mawson station as a
                  Senior Communications Technical Officer, says
                  his first moon bounce on May 4 this year, was
                  the first time it had been achieved from an
                  Australian Antarctic station and only the third
                  time from the Antarctic continent.
                  Until recently, the technique was only possible
                  using the largest, most powerful and expensive
                  amateur radio stations. This is because of the
                  distance the signal has to travel, the amount of
                  power needed to send a strong signal and the
                  loss of signal as it travels through space.
                  ‘The moon has to be lined up perfectly between
                  the two stations to achieve an adequate
                  reflection, so we use computer programs
                  to find the optimum time to communicate,’
                  Craig explains.
                  ‘However, most of the transmitted signal is lost
                  into free space and only about seven per cent of
                  the signal that strikes the moon is reflected; the
                  rest is absorbed.
                  ‘The Earth’s atmosphere distorts and attenuates
                  the signal even further so that by the time
                  the signal reaches the receiving station
                  it is very weak.’
                  As Craig is operating from a small, ‘home-made’
                  station, he can only communicate with receiving
                  stations that use multiple, ‘high gain’ antennas
                  and vast amounts of power.
                  Craig built his own radio station using an
                  off-the-shelf antenna that is small enough
                  not to get blown away in a blizzard, but large
                  enough to generate a signal that can reach the
                  moon. He also built an amplifier to boost his
                  transmitting signal from 4 watts to 500 watts.
                  To bounce a signal off the moon he uses
                  customised software to target it. Objects other
                  than the moon can also be used and Craig has
                  targeted commercial aircraft and meteor trails.
                  ‘The software is tailored for each
                  application,’ he says.
                  ‘It takes around 2.7 seconds for a signal to
                  be bounced off the moon, while it is virtually
                  instantaneous from an aircraft. If a signal comes
                  back, you can be sure it’s reflected off the object
                  you are targeting.’
                  Moon bounce from Antarctica
                  Amateur radio operator Craig Hayhow has used the moon to bounce
                  a radio signal 742 000 km, from Mawson station in Antarctica to
                  Cornwall in England.
                  Craig passed the exams to become an amateur
                  radio operator when he was 17 and some
                  30 years later he still enjoys the surprise of
                  chatting to people from around the world,
                  sometimes in remote or unusual places.
                  As Antarctica is also considered ‘remote’ and
                  ‘unusual’, Craig says he is often bombarded by
                  operators clamouring to add his unique call sign
                  to their log books.
                  Craig’s moon bounce achievement comes
                  100 years after the first radio communication
                  between Antarctica and Australia, via Macquarie
                  Island, was established by the Australasian
                  Antarctic Expedition (AAE, 1911–1914), led by
                  Douglas Mawson. The AAE was the first Antarctic
                  expedition to use radio communications,
                  using ground waves (Very Low Frequency or
                  VLF). Sadly, Mawson’s first use of the radio,
                  on 24 February 1913, was to relay news of
                  the deaths of his companions, Xavier Mertz
                  and Belgrave Ninnis, during the Far Eastern
                  sledging journey.
                  Fortunately, Craig’s experiences are happier.
                  ‘Usually the talk is of a technical nature, but
                  we also talk about work, family and the places
                  we live,’ he says.
                  ‘However, amateur radio is mostly about
                  furthering the science of radio by testing,
                  research and development, and sharing ideas
                  within the radio community.’
                  WENDY PYPER
                  Australian Antarctic Division 1

                  F-CYQL1

                  Comment


                  • Originally posted by VE6CPP View Post
                    For 'abcd567 and Rooster'.. Interesting article from 'AUSTRALIAN ANTARCTIC MAGAZINE"..

                    Moon bounce from Antarctica
                    Amateur radio operator Craig Hayhow has used the moon to bounce
                    a radio signal 742 000 km, from Mawson station in Antarctica to
                    Cornwall in England. .............
                    F-CYQL1
                    Thank you Jerry for sharing such a useful info. 73

                    Sent from my N762 using Tapatalk 2

                    Comment


                    • Originally posted by abcd567 View Post
                      Half wave dipole has the beauty that its impedance (73 ohm) matches with coaxial cable's impedance (75 ohm) and DVB-T receiver's impedance (also 75 ohms). Another advantage is that there is no velocity factor involved in calculating length, hence no assumptions, and it can be cut to accurately 13.8 cm total height, tip-to-tip. That is why one can get a gain almost equal to it's theoretical gain of 2.15dBi. On the other hand, although 4-element CoCo has a theretical gain of 5 dBi, the CoCo cut to wrong dimensions (due to assumption of velocity factor), may actually have much less than 5 dBi, even less than 2 dBi of 1/2 wave dipole.


                      Franklin half-over-half diploe has theoretical gain of 5 dBi and can be cut to precise dimensions like half wave dipole, but has a very high impedance (4000 ohms) and if proper matching method is not used, gives a low gain & poor coverage. I have covered loss of gain in Franklin by using 2 amplifiers, and got a very good coverage. But without amplifier and without impedance matching, Franklin gives poor performance.With Franklin, you must have at least one: either impedance matching or amplifier.


                      Sent from my N762 using Tapatalk 2
                      Thanks abcd567 for the explanation. A very informative post.

                      Mike

                      Comment


                      • Impedance-Matched Franklin Dipole
                        With 1/4 wavelength Impedance matching Stub & adjustable sliding tap

                        400 km Range Without Amplifier!!!

                        franklin+impedance-matching-stub-2.jpg
                        .
                        DSC02985R.jpg
                        .
                        DSC02989R.jpg
                        .
                        DSC02990R.jpg
                        .
                        DSC03002.jpg

                        Best position of sliding tap is found by trial & error. In case of antenna shown in the pictures above, the best tap position was found at 18mm from shorted end of stub (i.e about 25% of stub's total length of 69mm), but this may vary from antenna to antenna. The position of sliding tap for each individual antenna is to be adjusted by trial & error method.
                        Last edited by abcd567; 2014-01-02, 18:54.

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                        • Impressive!

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                          • Great work. I'm lucky to get 340km with an amp and CoCo.
                            I finally got all the pieces together to test a shorted 3 part Coco but only have a spare 12v adapter. Would 12v be enough to run the power inserter and onto the amp?
                            Last edited by mickopla; 2014-01-01, 12:01. Reason: wrong quote

                            Comment


                            • Originally posted by mickopla View Post
                              Great work. I'm lucky to get 340km with an amp and CoCo.
                              I finally got all the pieces together to test a shorted 3 part Coco but only have a spare 12v adapter. Would 12v be enough to run the power inserter and onto the amp?
                              12v worked for me - I'm not sure going to 15v made much difference (could be dependent on the amp)

                              Comment


                              • Originally posted by mickopla View Post
                                Great work. I'm lucky to get 340km with an amp and CoCo.........
                                Originally posted by peterhr View Post
                                Impressive!
                                You can built a mechanically stronger version of Franklin, suitable for outdoor installation, as shown here:

                                http://www.lesaunier.com/htm/franklin1_eng.htm


                                Note: It will be easier to carry out the adjustment of tap with Antenna at location easily accessible without need of a ladder or climbing to roof (unless you want to burn some of your fat ). Ranges can be compared for various settings, and once the best one is found, the antenna can be moved to & installed at roof top.

                                I have tried half-a-dozen different settings of cable tap between 10mm and 40mm (from shorted end of stub).
                                For each of these 6 settings, I have run the antenna on adsbScope for 24 hrs


                                .
                                Last edited by abcd567; 2014-01-01, 21:31.

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