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  • Originally posted by abcd567 View Post
    (3) Coax cable between antenna & receiver: 75 ohm RG6 - Very short length (11 feet / 3.5 meters).
    (4) In-Line Amplifier RCA D903 (13-18dB, 950 to 2050 MHz)

    There is a vast difference between ranges with & without in-Line amplifier.
    The quality of any radio tuner design is based on 2 things ... 'Sensitivity & Selectivity'

    In your experiment we can rule out that there is any significant line loss in the coax because it's very short.

    The first stage of the DVB-T Dongle's tuner will be a built in preamp. The gain set on this preamp is probably set lower then optimum for ADS-B reception as its real purpose is to be used as a ATSC TV receiver.

    It would be interesting if you could repeat the same experiment with various other tuners including a Mode-S Beast http://www.modesbeast.com/radarcape.html
    Last edited by 1090 MHz; 2013-11-21, 22:34.
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    • NO IN-LNE AMPLIFIER
      Trial run of CoCo (Coaxial Collinear) Antenna, comprising of three-and-half, 1/2-wavelength sections

      Cable length between antenna & DVB-T USB Receiver = 11 feet (3.5 meters)

      Cable used for Antenna as well as the feed line is RG6, which is commonly available at all cable/satellite TV stores.
      This commonly available cable has FPE (Foamed Polyeathylene) insulation of the core, which has a velocity factor of 0.8.
      The impedance of this cable is 75 ohms, which matches with the input impedance of DVB-T USB Dongle (75 ohms input).

      NO IN-LNE AMPLIFIER

      DSC02845R.jpg CoCo-No Amplifier-Coverage-48hr-trial run.jpg DSC02846R.jpg DSC02847R.jpg
      Last edited by abcd567; 2013-11-21, 18:24.

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      • WITH IN-LNE AMPLIFIER
        Trial run of CoCo (Coaxial Collinear) Antenna, comprising of three-and-half, 1/2-wavelength sections

        Cable length between antenna & DVB-T USB Receiver = 11 feet (3.5 meters)

        Cable used for Antenna as well as the feed line is RG6, which is commonly available at all cable/satellite TV stores.
        This commonly available cable has FPE (Foamed Polyeathylene) insulation of the core, which has a velocity factor of 0.8.
        The impedance of this cable is 75 ohms, which matches with the input impedance of in-Line Amplifier (75 ohms) as well as impedance of DVB-T USB Dongle (75 ohms input).

        WITH IN-LNE AMPLIFIER

        DSC02845R.jpg CoCo+Amplifier-Coverage-48hrs trial run.jpg DSC02842R.jpg DSC02843R.jpg DSC02844R.jpg
        Last edited by abcd567; 2013-11-21, 18:25.

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        • Remove the short at the top, and replace with a 1/4 whip.... You can then remove the dc blocking cap, and associated losses...
          LOVE the recycled splitter idea, ill be stealing that! ;-)

          Nice to see homebrew projects in detail... Kudos to you.

          Any idea if the amp will run on 12vdc?
          Thanks

          Sent using Tapatalk from my ZX81

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          • Originally posted by Rooster View Post
            Remove the short at the top, and replace with a 1/4 whip.... You can then remove the dc blocking cap, and associated losses...
            LOVE the recycled splitter idea, ill be stealing that! ;-)

            Nice to see homebrew projects in detail... Kudos to you.

            Any idea if the amp will run on 12vdc?
            Thanks

            Sent using Tapatalk from my ZX81
            Mine does, but I'll be changing to a 15v supply when I get around to it (might get a bit more gain)

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            • Great thanks.. Im a radio amateur, and have 13.8vdc next to the pc! Guess im going shopping tomorrow!

              Sent using Tapatalk from my ZX81

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              • Originally posted by Rooster View Post
                ... LOVE the recycled splitter idea, ill be stealing that! ;-)
                ...Nice to see homebrew projects in detail... Kudos to you.
                ....Any idea if the amp will run on 12vdc? .....
                Thanks for the compliments.
                It should work on 12V DC. These amplifiers have some tolerance limits. May be the Gain is a bit reduced due to lower voltage. I remember someone ( I think peterhr) stating in this forum that he is using 12V DC and it is working OK, but he said he will change to 14V when he finds time.
                Last edited by abcd567; 2013-11-26, 03:37.

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                • If u r going to shop for in-line amplifier and live in GTA (Toronto, Mississauga etcc) I can give u the address of store from where I purchased it for $4 only.

                  Sent from my N762 using Tapatalk 2

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                  • Bit of a drive from the uk! Lol

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                    • If the RCA D903 is ordered from Amazon or eBay, cost+shipment is between $10 & $20. One living in Greater Toronto Area can benefit in terms of cost & shipping time, but will have to visit the store as they dont sell on line.

                      Sent from my N762 using Tapatalk 2

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                      • Originally posted by Rooster View Post
                        Bit of a drive from the uk!
                        Lol

                        Sent from my N762 using Tapatalk 2

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                        • Originally posted by abcd567 View Post
                          If u r going to shop for in-line amplifier and live in GTA (Toronto, Mississauga etcc) I can give u the address of store from where I purchased it for $4 only.
                          Is that A&A Electronics in Mississauga @ Matheson Blvd,? aa-e.com

                          They always have amazing prices .... I always pop in this place when I'm in the area.. and there is also a bunch of other competitors in the same plaza.
                          Last edited by 1090 MHz; 2013-11-22, 00:35.
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                          • Originally posted by 1090 MHz View Post
                            Is that A&A Electronics in Mississauga @ Matheson Blvd,? aa-e.com

                            They always have amazing prices .... I always pop in this place when I'm in the area.. and there is also a bunch of other competitors in the same plaza.
                            You guessed very close. It is "Sayyal Electronics" next door to AA Electronics, in the same building. I do visit both AA Electronics & Sayyal when I need stuff like that.

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                            • Sorry, I misspelled. It is with onr y not two y
                              http://www.sayal.com

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                              • Originally posted by abcd567 View Post
                                You guessed very close. It is "Sayyal Electronics" next door to AA Electronics, in the same building. I do visit both AA Electronics & Sayyal when I need stuff like that.
                                Yes and there is another called RTC all in the same building @ 1350 Matheson Blvd

                                AA Electronics, 1350 Matheson Blvd. Unit 8
                                Sayal Electronics, 1350 Matheson Blvd. Units 3-4
                                RTC Electronics, 1350 Matheson Blvd. Unit 10A

                                It's a candy shop of electronics !!!

                                And when your done there, if you have any money left, you can head on over to Matheson's Exotic Bar.
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                                Last edited by 1090 MHz; 2013-11-22, 01:41.
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