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  • Originally posted by 747-8F View Post
    I made same antenna like you made it to see how far it works. With RadioShack in-line amplifier 950-2050Mhz...
    But it didn't work well, the longest range was 70nm!
    So what do you think, is it wrong with Amplifier or something else?
    I live in an apartment 8th floor so that's high enough.
    Did you try it without the Amp? An Amp like that has a wide broadband range and will amplify everything from 950-2050Mhz like cell phone towers @ 1700 & 1900MHz. If you're close to a cell tower the Amp could be getting overloaded.
    www.ADS-B.ca

    Comment


    • Originally posted by 1090 MHz View Post
      Did you try it without the Amp? An Amp like that has a wide broadband range and will amplify everything from 950-2050Mhz like cell phone towers @ 1700 & 1900MHz. If you're close to a cell tower the Amp could be getting overloaded.
      Agreed - I remember going on a time management course where they emphasized 'eat your elephant in slices - if you try to swallow it whole it'll choke you' - break the problem down, test a bit at a time.

      It could also be the the amplifier is not receiving power

      Comment


      • Originally posted by peterhr View Post
        Agreed - I remember going on a time management course where they emphasized 'eat your elephant in slices - if you try to swallow it whole it'll choke you' - break the problem down, test a bit at a time.

        It could also be the the amplifier is not receiving power
        You can check the availability of power to amplifier by measuring voltage across two tips of the Dipole. Please see image below.
        Alternatively voltage measurement can be done between Amplifier's metallic body (-ve) and the tip of Dipole's that leg which is connected to central conductor (+ve)

        Measurement.jpg

        .

        Comment


        • Looks like the RadioShack Amplifier needs power supply.

          Does RCA D903 inline amplifier need power supply? Because I saw it on ebay it says "Unit powers it self through RCA DBS system"
          Last edited by 747-8F; 2013-11-01, 02:18.

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          • Originally posted by 747-8F View Post
            Looks like the RadioShack Amplifier needs power supply.

            Does RCA D903 inline amplifier need power supply? Because I saw it on ebay it says "Unit powers it self through RCA DBS system"
            An RCA DBS system is a DirecTV Satellite system which will have 13 to 18 volts on the coax to power the LNB... the LNB is the round thing at the dish that picks up the satellite signals. In your case you need to add a power injector to add that DC voltage to the coax to power the amp.
            www.ADS-B.ca

            Comment


            • Originally posted by 747-8F View Post
              Looks like the RadioShack Amplifier needs power supply.

              Does RCA D903 inline amplifier need power supply? Because I saw it on ebay it says "Unit powers it self through RCA DBS system"
              Satellite Receivers supply power to LNB of the dish antenna through the coaxial cable. Any in-Line amplifier installed uses the DC available on the coaxial cable, and does not need a separate power supply, and hence the eBay statement "Unit powers it self through RCA DBS system"

              The ADS-B Receivers generally do not supply DC power to antenna. The in-Line amplifier therefore requires a power supply. This is done by installing a "power-inserter" + an AC-DC adaptor . These may be available from various suppliers like eBay, Amazon etc. Purchase the one which matches the frequency range and voltage of your in-Line amplifier.


              I have made my own power inserter. Please see attached images. If you decide to built one, you can omit the"Demuxer" part (the home-made coil + FM/AIR Band whip antenna) shown in the schematic.

              NOTE: I use 2 in-Line Amplifiers due to long length and poor quality of coaxial cable.

              BIAS-T-02.jpg tt0.gif DSC02675.gif DSC02576-R90c.jpg
              Last edited by abcd567; 2013-11-01, 03:57.

              Comment


              • Originally posted by abcd567 View Post
                Satellite Receivers supply power to LNB of the dish antenna through the coaxial cable. Any in-Line amplifier installed uses the DC available on the coaxial cable, and does not need a separate power supply, and hence the eBay statement "Unit powers it self through RCA DBS system"

                The ADS-B Receivers generally do not supply DC power to antenna. The in-Line amplifier therefore requires a power supply. This is done by installing a "power-inserter" or "bias-t" + an AC-DC adaptor . These may be available from various suppliers like eBay, Amazon etc. Purchase the one which matches the frequency range and voltage of your in-Line amplifier.


                I have made my own power inserter. Please see attached images. If you decide to built one, you can omit the"Demuxer" part (the home-made coil connecting FM/AIR Band whip antenna) shown in the schematic.

                [ATTACH=CONFIG]2836[/ATTACH] [ATTACH=CONFIG]2835[/ATTACH] [ATTACH=CONFIG]2834[/ATTACH] [ATTACH=CONFIG]2837[/ATTACH]
                Thanks,

                I see it, do you think this power injector will work with that inline amplifier I showed you instead of that one comes with the injector ?

                I can't wait to try it, but I am not sure because it says,

                Power Injector
                Input........12V DC
                Insertion Loss........Max. 3db
                AC/DC Adapter
                Input........120V AC, 60Hz
                Output.........12 DC, 200mA, Tip positive.

                The inline amplifier I have is power pass DC 14-18V 25-40mA, so ?
                Last edited by 747-8F; 2013-11-01, 04:42. Reason: I add more information

                Comment


                • I can't wait to try it, but I am not sure because it says,

                  Power Injector
                  Input........12V DC
                  Insertion Loss........Max. 3db
                  AC/DC Adapter
                  Input........120V AC, 60Hz
                  Output.........12 DC, 200mA, Tip positive.

                  The inline amplifier I have is power pass DC 14-18V 25-40mA, so ?

                  Comment


                  • Originally posted by 747-8F View Post
                    Thanks,

                    I see it, do you think this power injector will work with that inline amplifier I showed you instead of that one comes with the injector ?
                    The in-Line amplifier ( RadioShack® In-Line Signal Amplifier Catalog #: 15-369 | Model: 15-369 ), shown by clicking the link you provided, says "from 50MHz to 900MHz", while ADS-B is 1090 MHz, outside this range.

                    Comment


                    • Originally posted by 747-8F View Post
                      I can't wait to try it, but I am not sure because it says,

                      Power Injector
                      Input........12V DC
                      Insertion Loss........Max. 3db
                      AC/DC Adapter
                      Input........120V AC, 60Hz
                      Output.........12 DC, 200mA, Tip positive.

                      The inline amplifier I have is power pass DC 14-18V 25-40mA, so ?
                      (1) Current rating (200 mA) of AC/DC Adapter is OK, as the Amplifier needs only 25-40mA.
                      (2) The Voltage output of AC/DC Adapter is 12 Volts, slightly less than 14-18 Volts of the Amplifier. In most cases this will be OK, but in some cases it may cause lower gain or improper working of the Amplifier. If you have already purchased it, give it a try and see.
                      (3) What is the frequency range covered? Does it cover ADS-B frequency 1090 MHz?
                      (4) "Power Pass" Amplifier means DC applied at one terminal of amplifier is passed to the other terminal of Amplifier. DC will therefore reach the Antenna. This is not a problem as long as you do not short the two legs of the Antenna.
                      Last edited by abcd567; 2013-11-01, 05:34.

                      Comment


                      • Originally posted by abcd567 View Post
                        The in-Line amplifier ( RadioShack® In-Line Signal Amplifier Catalog #: 15-369 | Model: 15-369 ), shown by clicking the link you provided, says "from 50MHz to 900MHz", while ADS-B is 1090 MHz, outside this range.
                        You right that amplifier comes in that box is 50-900MHz, but I asked do you think it will work if I connect the amplifier I have 950-250MHz to that power injector instead of this amplifier 50-900Mhz.

                        Comment


                        • Did you try it without the amplifier connected? Right now that none-powered amp will act as a big attenuator, and amazingly you're still getting something... so that's telling me you have strong signals up there on the 8th floor. Remove the amp from the coax line and see what you then get... I bet it'll work a lot better.
                          www.ADS-B.ca

                          Comment


                          • Originally posted by 1090 MHz View Post
                            Did you try it without the amplifier connected? Right now that none-powered amp will act as a big attenuator, and amazingly you're still getting something... so that's telling me you have strong signals up there on the 8th floor. Remove the amp from the coax line and see what you then get... I bet it'll work a lot better.
                            I agree with you. Removing the un-powered amplifier is worth giving a try.
                            The reason I used Amplifier was not the low gain or poor performance of Antenna. It was mainly due to long length of cheap, high attenuation coaxial cable.
                            Last edited by abcd567; 2013-11-01, 05:47.

                            Comment


                            • I run my in line amp on 12v - it does work, but I do intend to change to a 15v supply when I find time (as well as make up the Franklin - from 3/16" copper car brake line - so it can go outside in the wind and rain)

                              I would think the power injector for to 50-900Mhz amp would be fine - we are only slightly out of the range on the kit and the limit in the kit is likely to be the amplifier, not the injector.

                              Do not try to just put 15v directly onto the coax cable without an injector ... doing so might just fry the dongle and the circuit in the power supply would certainly kill and signals coming down the wire.

                              Comment


                              • Originally posted by peterhr View Post
                                I run my in line amp on 12v - it does work, but I do intend to change to a 15v supply when I find time (as well as make up the Franklin - from 3/16" copper car brake line - so it can go outside in the wind and rain)

                                I would think the power injector for to 50-900Mhz amp would be fine - we are only slightly out of the range on the kit and the limit in the kit is likely to be the amplifier, not the injector.

                                Do not try to just put 15v directly onto the coax cable without an injector ... doing so might just fry the dongle and the circuit in the power supply would certainly kill and signals coming down the wire.

                                What you described is exactly the purpose of power-injector, i.e.
                                (1) to prevent DC 15 V reaching the Reveiver/Dongle.
                                (2) to prevent ADS-B signals short circuiting through the power supply.
                                Normally this is achieved by providing a DC blocking band-pass filter matching the frequency range of the Amplifier.

                                In our case, since only one frequency (1090 MHz) is involved, a band-pass filter is not required and the target can be achieved simply by only two components i.e.
                                (1) DC blocking is done by a capacitor connected on the receiver side,
                                (2) RF Signal short-circuiting is prevented by a RF Choke (inductor) connected to the power supply side.

                                This is so simple that I home made it using a simple coax cable splitter ($2.50). I removed all the components inside the splitter, used the housing only. I then soldered a 200 pF capacitor ($0.25) between the antenna and receiver terminals of the splitter, and soldered a 3.3 microHenry ($1.20) molded-case axial inductor between antenna & DC terminals of the splitter. I could not find a 15V AC-DC Adapter, but did find a 14V AC-DC Adapter which is working OK.

                                I also added a home-made air coil to hook-up FM/Air Band Whip antenna to enable me to use the Dongle as FM/Air Band Radio for occasionally listening Music or Air Band. This part (home-made coil & Whip Antenna ) are not required by ADS-B and can be omitted.

                                Please see attached pictures.

                                BIAS-T-02.jpg tt0.gif

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