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Internal Sound Card Problems?

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  • Ulf Holt
    I have now tested my SoftRock RX Ensemble II for some time. I still don t have access to an antenna I can be proud of, my only antenna so far is a short line
    Message 1 of 15 , Nov 25, 2012
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      I have now tested my SoftRock RX Ensemble II for some time. I still don't have access to an antenna I can be proud of, my only antenna so far is a short line on the balcony, surrounded with concrete walls on 3 sides.
       
      I have tried the following software:
       
      PowerSDR-iq, HDSDR, Winrad and Rocky. All seem to work, but I wonder if I need a better sound card. I can observe the following:
       
      PowerSDR-iq shows a 50 dB peak at a frequency ca 12 khz below the center frequency, and a lot of smaller peaks at frequencies higher than the center frequency.
       
      HDSDR does not have the same quality on the Spectrum as the Panadapter in PowerSDR, but indicates a +50 dB peak at the center frequency and some smaller peaks at higher frequencies. It also shows that the signal is + 10 - 15 dB over S9, without an antenna hooked up.
       
      Rocky shows the same kind of information, but is harder to evaluate.
       
      I have screenshots of these things, but I don't know if it is possible to attach pictures to this group.
       
      Does this inidcate I should go for a better sound card?
       
      73 de LA2SL
       
      Ulf
    • rifkum
      I have had the best luck with HDSDR. I also have a signal spike at the center frequency. That is fairly normal. It is actually zero hertz, the spectrum
      Message 2 of 15 , Nov 25, 2012
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        I have had the best luck with HDSDR. I also have a "signal" spike at the center frequency. That is fairly normal. It is actually zero hertz, the spectrum spreads out left and right +/- of zero and most sound cards apparently show some noise at that very low freq.

        I have not calibrated my "s" meter yet and really ignore the values it displays, for now.

        I found that I had mirroring of stronger signals and was able to greatly reduce the mirroring by going into the "options" "channel skew calibreation" and making adjustments there.

        You should try and find a fairly constant signal, like wwv at 5, 10, 15 mhz, etc. or a strong broadcast AM signal so I could observe the carrier spike while making the adjustment to reduce the mirroring.

        First though I calibrated the Si570 chip using these instructions...

        https://sites.google.com/site/g4zfqradio/calibrating-the-softrock-si570-usb-controller

        there is a lot of good info here ...
        https://sites.google.com/site/g4zfqradio/home

        good luck
        dwight
        N7KBC
      • MIKE DURKIN
        Why? You you re self said your antenna is below sub standard ... If the spikes are still obstructive .... with a good antenna, that s a good time to deal with
        Message 3 of 15 , Nov 25, 2012
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          Why?

          You you're self said your antenna is below sub standard ...

          If the spikes are still obstructive .... with a good antenna, that's a good time to deal with the soundcard....

          I only have 2 spikes above my local noisefloor (besides the center)... lots with no antenna .... I work around the spikes if I realy need to ... ie shift lo some and copy away!! But not usually needed.

          KC7NOA



          To: softrock40@yahoogroups.com
          From: ulf.holt@...
          Date: Mon, 26 Nov 2012 08:21:53 +0700
          Subject: [softrock40] Internal Sound Card Problems?

           
          I have now tested my SoftRock RX Ensemble II for some time. I still don't have access to an antenna I can be proud of, my only antenna so far is a short line on the balcony, surrounded with concrete walls on 3 sides.
           
          I have tried the following software:
           
          PowerSDR-iq, HDSDR, Winrad and Rocky. All seem to work, but I wonder if I need a better sound card. I can observe the following:
           
          PowerSDR-iq shows a 50 dB peak at a frequency ca 12 khz below the center frequency, and a lot of smaller peaks at frequencies higher than the center frequency.
           
          HDSDR does not have the same quality on the Spectrum as the Panadapter in PowerSDR, but indicates a +50 dB peak at the center frequency and some smaller peaks at higher frequencies. It also shows that the signal is + 10 - 15 dB over S9, without an antenna hooked up.
           
          Rocky shows the same kind of information, but is harder to evaluate.
           
          I have screenshots of these things, but I don't know if it is possible to attach pictures to this group.
           
          Does this inidcate I should go for a better sound card?
           
          73 de LA2SL
           
          Ulf

        • Ulf Holt Gmail
          Mike, you always ask the right questions! Well, below sub standard is an understatement, and I will try to fix the problem before going any further. Main
          Message 4 of 15 , Nov 25, 2012
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            Mike, you always ask the right questions!

            Well, below sub standard is an understatement, and I will try to fix the problem before going any further. Main problem is to find parts for an antenna, since my Thai is none existing, and it's hard to find a shop when you cannot ask people for directions. I think I will go for a magnetic loop, and got a description where I need 32" of 1" aluminum tube, bent to form a circle, and a coax inside. I will be able to get a coax, but here in Pattaya I have no ideas where to get the aluminum, but I'll be going to BKK next week, and I'm sure I can find what I need in Chinatown. Only problem with this construction is that the aluminum tube should be grounded, and ground is non-existing in the building where we live. 

            73 de LA2SL
            Ulf
             

            Why?

            You you're self said your antenna is below sub standard ...

            If the spikes are still obstructive .... with a good antenna, that's a good time to deal with the soundcard....

            I only have 2 spikes above my local noisefloor (besides the center)... lots with no antenna .... I work around the spikes if I realy need to ... ie shift lo some and copy away!! But not usually needed.

            KC7NOA



            To: softrock40@yahoogroups.com
            From: ulf.holt@...
            Date: Mon, 26 Nov 2012 08:21:53 +0700
            Subject: [softrock40] Internal Sound Card Problems?

             
            I have now tested my SoftRock RX Ensemble II for some time. I still don't have access to an antenna I can be proud of, my only antenna so far is a short line on the balcony, surrounded with concrete walls on 3 sides.
             
            I have tried the following software:
             
            PowerSDR-iq, HDSDR, Winrad and Rocky. All seem to work, but I wonder if I need a better sound card. I can observe the following:
             
            PowerSDR-iq shows a 50 dB peak at a frequency ca 12 khz below the center frequency, and a lot of smaller peaks at frequencies higher than the center frequency.
             
            HDSDR does not have the same quality on the Spectrum as the Panadapter in PowerSDR, but indicates a +50 dB peak at the center frequency and some smaller peaks at higher frequencies. It also shows that the signal is + 10 - 15 dB over S9, without an antenna hooked up.
             
            Rocky shows the same kind of information, but is harder to evaluate.
             
            I have screenshots of these things, but I don't know if it is possible to attach pictures to this group.
             
            Does this inidcate I should go for a better sound card?
             
            73 de LA2SL
             
            Ulf

          • MIKE DURKIN
            Build a tuned loop .... need an air capacitor (vacume prefered- but that s MONEY!!) And bamboo for suports ...( so it ll be square/rectangle- so what! !!
            Message 5 of 15 , Nov 25, 2012
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              Build a tuned loop .... need an air capacitor (vacume prefered- but that's MONEY!!) And bamboo for suports ...( so it'll be square/rectangle- so what! !! You're gona tune it anyway)
              Mag loops are cool too ... but coax .... I don't think it matters what coax ... its knowing the velocity of the dielectric more important (!I think) ....

              KC7NOA


              To: softrock40@yahoogroups.com
              From: ulf.holt@...
              Date: Mon, 26 Nov 2012 09:54:51 +0700
              Subject: Re: [softrock40] Internal Sound Card Problems?

               
              Mike, you always ask the right questions!

              Well, below sub standard is an understatement, and I will try to fix the problem before going any further. Main problem is to find parts for an antenna, since my Thai is none existing, and it's hard to find a shop when you cannot ask people for directions. I think I will go for a magnetic loop, and got a description where I need 32" of 1" aluminum tube, bent to form a circle, and a coax inside. I will be able to get a coax, but here in Pattaya I have no ideas where to get the aluminum, but I'll be going to BKK next week, and I'm sure I can find what I need in Chinatown. Only problem with this construction is that the aluminum tube should be grounded, and ground is non-existing in the building where we live. 

              73 de LA2SL
              Ulf
               


              Why?

              You you're self said your antenna is below sub standard ...

              If the spikes are still obstructive .... with a good antenna, that's a good time to deal with the soundcard....

              I only have 2 spikes above my local noisefloor (besides the center)... lots with no antenna .... I work around the spikes if I realy need to ... ie shift lo some and copy away!! But not usually needed.

              KC7NOA



              To: softrock40@yahoogroups.com
              From: ulf.holt@...
              Date: Mon, 26 Nov 2012 08:21:53 +0700
              Subject: [softrock40] Internal Sound Card Problems?

               
              I have now tested my SoftRock RX Ensemble II for some time. I still don't have access to an antenna I can be proud of, my only antenna so far is a short line on the balcony, surrounded with concrete walls on 3 sides.
               
              I have tried the following software:
               
              PowerSDR-iq, HDSDR, Winrad and Rocky. All seem to work, but I wonder if I need a better sound card. I can observe the following:
               
              PowerSDR-iq shows a 50 dB peak at a frequency ca 12 khz below the center frequency, and a lot of smaller peaks at frequencies higher than the center frequency.
               
              HDSDR does not have the same quality on the Spectrum as the Panadapter in PowerSDR, but indicates a +50 dB peak at the center frequency and some smaller peaks at higher frequencies. It also shows that the signal is + 10 - 15 dB over S9, without an antenna hooked up.
               
              Rocky shows the same kind of information, but is harder to evaluate.
               
              I have screenshots of these things, but I don't know if it is possible to attach pictures to this group.
               
              Does this inidcate I should go for a better sound card?
               
              73 de LA2SL
               
              Ulf


            • Jasmine Strong
              ... Use 1/2 thin copper pipe; it s easy to bend by hand (and is more conductive anyway). -J.
              Message 6 of 15 , Nov 25, 2012
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                On 25 Nov 2012, at 18:54, Ulf Holt Gmail <ulf.holt@...> wrote:
                > I think I will go for a magnetic loop, and got a description where I need 32" of 1" aluminum tube, bent to form a circle, and a coax inside. I will be able to get a coax, but here in Pattaya I have no ideas where to get the aluminium,

                Use 1/2" thin copper pipe; it's easy to bend by hand (and is more conductive anyway).

                -J.
              • Ulf Holt Gmail
                That s a good idea, but what about the dimension. Mike do I really need a variable capacitor when it s only RX? I know the signals will be stronger if I tune
                Message 7 of 15 , Nov 25, 2012
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                  That's a good idea, but what about the dimension.

                  Mike do I really need a variable capacitor when it's only RX? I know the signals will be stronger if I tune the antenna, but again to your suggestion, what about values and dimension. I know next to nothing about antennas, feeding etc.




                   


                  On 25 Nov 2012, at 18:54, Ulf Holt Gmail <ulf.holt@...> wrote:
                  > I think I will go for a magnetic loop, and got a description where I need 32" of 1" aluminum tube, bent to form a circle, and a coax inside. I will be able to get a coax, but here in Pattaya I have no ideas where to get the aluminium,

                  Use 1/2" thin copper pipe; it's easy to bend by hand (and is more conductive anyway).

                  -J.

                • MIKE DURKIN
                  That kinda depends on the area you have to use ... but a dipole is easy ... a horizontal loop (on the ceiling or higher) is less prone to local electrical
                  Message 8 of 15 , Nov 25, 2012
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                    That kinda depends on the area you have to use ... but a dipole is easy ... a horizontal loop (on the ceiling or higher) is less prone to local electrical noise. You can use a binocular core to make a 4:1 or 9:1 balun .... I get them from CB linear's here in the states.

                    Lots of info on the net about antennas ... its easyer then building the sdr by far ....

                    KC7NOA



                    To: softrock40@yahoogroups.com
                    From: ulf.holt@...
                    Date: Mon, 26 Nov 2012 10:27:06 +0700
                    Subject: Re: [softrock40] Internal Sound Card Problems?

                     
                    That's a good idea, but what about the dimension.

                    Mike do I really need a variable capacitor when it's only RX? I know the signals will be stronger if I tune the antenna, but again to your suggestion, what about values and dimension. I know next to nothing about antennas, feeding etc.




                     


                    On 25 Nov 2012, at 18:54, Ulf Holt Gmail <ulf.holt@...> wrote:
                    > I think I will go for a magnetic loop, and got a description where I need 32" of 1" aluminum tube, bent to form a circle, and a coax inside. I will be able to get a coax, but here in Pattaya I have no ideas where to get the aluminium,

                    Use 1/2" thin copper pipe; it's easy to bend by hand (and is more conductive anyway).

                    -J.

                  • Ulf Holt Gmail
                    Well, I live on second floor in a block that is 18 floors high. Dipole is an impossible task, we are facing the swimming pool, an the opening to free air at
                    Message 9 of 15 , Nov 25, 2012
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                      Well, I live on second floor in a block that is 18 floors high. Dipole is an impossible task, we are facing the swimming pool, an the opening to free air at the balcony is 5 x 12 feet, that's what I have to deal with.

                      Sendt fra min iPad

                      Den 26. nov. 2012 kl. 10:41 skrev MIKE DURKIN <Patriot121@...>:

                       

                      That kinda depends on the area you have to use ... but a dipole is easy ... a horizontal loop (on the ceiling or higher) is less prone to local electrical noise. You can use a binocular core to make a 4:1 or 9:1 balun .... I get them from CB linear's here in the states.

                      Lots of info on the net about antennas ... its easyer then building the sdr by far ....

                      KC7NOA



                      To: softrock40@yahoogroups.com
                      From: ulf.holt@...
                      Date: Mon, 26 Nov 2012 10:27:06 +0700
                      Subject: Re: [softrock40] Internal Sound Card Problems?

                       
                      That's a good idea, but what about the dimension.

                      Mike do I really need a variable capacitor when it's only RX? I know the signals will be stronger if I tune the antenna, but again to your suggestion, what about values and dimension. I know next to nothing about antennas, feeding etc.




                       


                      On 25 Nov 2012, at 18:54, Ulf Holt Gmail <ulf.holt@...> wrote:
                      > I think I will go for a magnetic loop, and got a description where I need 32" of 1" aluminum tube, bent to form a circle, and a coax inside. I will be able to get a coax, but here in Pattaya I have no ideas where to get the aluminium,

                      Use 1/2" thin copper pipe; it's easy to bend by hand (and is more conductive anyway).

                      -J.

                    • Alan
                      ... Sent: Monday, November 26, 2012 1:21 AM Subject: [softrock40] Internal Sound Card Problems? ... Ulf, Many soundcards show a single sharp spike at zero Hz.
                      Message 10 of 15 , Nov 25, 2012
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                        ----- Original Message -----
                        Sent: Monday, November 26, 2012 1:21 AM
                        Subject: [softrock40] Internal Sound Card Problems?


                        > I wonder if I
                        > need a better sound card. I can observe the following:
                        >
                        > PowerSDR-iq shows a 50 dB peak at a frequency ca 12 khz below the center
                        > frequency, and a lot of smaller peaks at frequencies higher than the center
                        > frequency.
                        >
                        > HDSDR does not have the same quality on the Spectrum as the Panadapter in
                        > PowerSDR, but indicates a +50 dB peak at the center frequency and some
                        > smaller peaks at higher frequencies.

                        Ulf,

                        Many soundcards show a single sharp spike at zero Hz. This is seen at the centre of the HDSDR display. PSDR has an offset so that
                        area is avoided. 12KHz, or whatever the IF is set.

                        If the spike is the only "fault" you observe with the soundcard then I say the spike helps you know where the centre is so you can
                        avoid it.
                        In your particular situation I doubt you will see any difference with an expensive card except that it will most likely have a much
                        smaller spike.
                        When you get home if you have a quiet radio location you may think differently.

                        Any "signals" each side of the spike will be due to ground loops or noise pickup. Normally nothing to do with the quality of the
                        card.

                        It also shows that the signal is + 10
                        > - 15 dB over S9, without an antenna hooked up.
                        >

                        Like PSDR HDSDR has a calibration facility needing a calibrated generator. Hover mouse on meter or look in Options - Misc. In your
                        situation I expect the noise will be high.

                        >
                        > I have screenshots of these things, but I don't know if it is possible to
                        > attach pictures to this group.
                        >

                        If you use email just attach. If you use the web interface then I think you have to use the Photos area of the group.

                        73 Alan G4ZFQ
                      • Lawrence Galea
                        I don t know if you are able to do this, but anyway here is a suggestion. A very thin winding wire protected by winding it a few turns every foot and perhaps
                        Message 11 of 15 , Nov 26, 2012
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                          I don't know if you are able to do this, but anyway here is a suggestion.
                          A very thin winding wire protected by winding it a few turns every foot and perhaps tying it every foot or so to a very thin nylon fishing line will be nearly invisible. As floors are normally about 3 metres high, taking it up from your balcony to the roof will be about 45 metres or more if you extend it horizontally on the roof which will be a good antenna to play with. During the night you can extend its separation from the walls by using a fibreglass fishing rod attached horizontally to your balcony.
                          Regards
                          Lawrence


                          Da: Ulf Holt Gmail <ulf.holt@...>
                          A: "softrock40@yahoogroups.com" <softrock40@yahoogroups.com>
                          Inviato: Lunedì 26 Novembre 2012 6:26
                          Oggetto: Re: [softrock40] Internal Sound Card Problems?

                           
                          Well, I live on second floor in a block that is 18 floors high. Dipole is an impossible task, we are facing the swimming pool, an the opening to free air at the balcony is 5 x 12 feet, that's what I have to deal with.

                          Sendt fra min iPad

                          Den 26. nov. 2012 kl. 10:41 skrev MIKE DURKIN <Patriot121@...>:

                           
                          That kinda depends on the area you have to use ... but a dipole is easy ... a horizontal loop (on the ceiling or higher) is less prone to local electrical noise. You can use a binocular core to make a 4:1 or 9:1 balun .... I get them from CB linear's here in the states.

                          Lots of info on the net about antennas ... its easyer then building the sdr by far ....

                          KC7NOA



                          To: softrock40@yahoogroups.com
                          From: ulf.holt@...
                          Date: Mon, 26 Nov 2012 10:27:06 +0700
                          Subject: Re: [softrock40] Internal Sound Card Problems?

                           
                          That's a good idea, but what about the dimension.

                          Mike do I really need a variable capacitor when it's only RX? I know the signals will be stronger if I tune the antenna, but again to your suggestion, what about values and dimension. I know next to nothing about antennas, feeding etc.




                           

                          On 25 Nov 2012, at 18:54, Ulf Holt Gmail <ulf.holt@...> wrote:
                          > I think I will go for a magnetic loop, and got a description where I need 32" of 1" aluminum tube, bent to form a circle, and a coax inside. I will be able to get a coax, but here in Pattaya I have no ideas where to get the aluminium,

                          Use 1/2" thin copper pipe; it's easy to bend by hand (and is more conductive anyway).

                          -J.


                        • Lawrence Galea
                          Vehicles parts shops are usually a good source for copper tuning as it s usually used in brakes systems. Other sources may be air conditioning,
                          Message 12 of 15 , Nov 26, 2012
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                            Vehicles parts shops are usually a good source for copper tuning as it's usually used in brakes systems.
                            Other sources may be air conditioning, refrigerator/freezer repair shops and gas shops.
                            Regards
                            Lawrence


                            Da: Ulf Holt Gmail <ulf.holt@...>
                            A: "softrock40@yahoogroups.com" <softrock40@yahoogroups.com>
                            Inviato: Lunedì 26 Novembre 2012 3:54
                            Oggetto: Re: [softrock40] Internal Sound Card Problems?

                             
                            Mike, you always ask the right questions!

                            Well, below sub standard is an understatement, and I will try to fix the problem before going any further. Main problem is to find parts for an antenna, since my Thai is none existing, and it's hard to find a shop when you cannot ask people for directions. I think I will go for a magnetic loop, and got a description where I need 32" of 1" aluminum tube, bent to form a circle, and a coax inside. I will be able to get a coax, but here in Pattaya I have no ideas where to get the aluminum, but I'll be going to BKK next week, and I'm sure I can find what I need in Chinatown. Only problem with this construction is that the aluminum tube should be grounded, and ground is non-existing in the building where we live. 

                            73 de LA2SL
                            Ulf
                             
                            Why?

                            You you're self said your antenna is below sub standard ...

                            If the spikes are still obstructive .... with a good antenna, that's a good time to deal with the soundcard....

                            I only have 2 spikes above my local noisefloor (besides the center)... lots with no antenna .... I work around the spikes if I realy need to ... ie shift lo some and copy away!! But not usually needed.

                            KC7NOA



                            To: softrock40@yahoogroups.com
                            From: ulf.holt@...
                            Date: Mon, 26 Nov 2012 08:21:53 +0700
                            Subject: [softrock40] Internal Sound Card Problems?

                             
                            I have now tested my SoftRock RX Ensemble II for some time. I still don't have access to an antenna I can be proud of, my only antenna so far is a short line on the balcony, surrounded with concrete walls on 3 sides.
                             
                            I have tried the following software:
                             
                            PowerSDR-iq, HDSDR, Winrad and Rocky. All seem to work, but I wonder if I need a better sound card. I can observe the following:
                             
                            PowerSDR-iq shows a 50 dB peak at a frequency ca 12 khz below the center frequency, and a lot of smaller peaks at frequencies higher than the center frequency.
                             
                            HDSDR does not have the same quality on the Spectrum as the Panadapter in PowerSDR, but indicates a +50 dB peak at the center frequency and some smaller peaks at higher frequencies. It also shows that the signal is + 10 - 15 dB over S9, without an antenna hooked up.
                             
                            Rocky shows the same kind of information, but is harder to evaluate.
                             
                            I have screenshots of these things, but I don't know if it is possible to attach pictures to this group.
                             
                            Does this inidcate I should go for a better sound card?
                             
                            73 de LA2SL
                             
                            Ulf



                          • warrenallgyer
                            Similar to Lawrence s suggestion: I live on the 18th floor and the space at the ground level below is a parking lot. I used #24 hookup wire, 130 or so feet on
                            Message 13 of 15 , Nov 26, 2012
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                              Similar to Lawrence's suggestion: I live on the 18th floor and the space at the ground level below is a parking lot. I used #24 hookup wire, 130 or so feet on a side, in an inverted vee with the apex on my balcony. the ends are tied to some 15 pound test fishing line which is tied off on the security fence on the far side of the parking lot (tied off at about 4A on a dark night :-) ), as far to the left and right as I could do it. The angle of separation is about 90 degrees. I use an inexpensive MFJ tuner and a very short length of twin lead to connect the antenna to my various RXTX and Peaberry. There is nothing magic about the length but I wanted it to be long enough that I could tune it for 160. The antenna is absolutely invisible and works great.... check my WSPR spot logs.

                              Many folks swear by the mag loop and I have no evidence to rebut them. But I like wire.... a lot of wire!

                              Where there is a will there is a way!

                              Warren Allgyer
                              W8TOD/BG1
                              Stealth Amateur Radio from Beijing
                              CW, BPSK31, and WSPR on 160 - 10 Meters

                              --- In softrock40@yahoogroups.com, Lawrence Galea <galea_lawrence@...> wrote:
                              >
                              > I don't know if you are able to do this, but anyway here is a suggestion.
                              >
                              > A very thin winding wire protected by winding it a few turns every foot and perhaps tying it every foot or so to a very thin nylon fishing line will be nearly invisible. As floors are normally about 3 metres high, taking it up from your balcony to the roof will be about 45 metres or more if you extend it horizontally on the roof which will be a good antenna to play with. During the night you can extend its separation from the walls by using a fibreglass fishing rod attached horizontally to your balcony.
                              > Regards
                              > Lawrence
                            • Tom Clifton
                              ... A bicycle wheel rim is also suitable. While aluminum is preferable, steel will work as well.   Take out the spokes and away you go.
                              Message 14 of 15 , Nov 26, 2012
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                                > On 25 Nov 2012, at 18:54, Ulf Holt Gmail <ulf.holt@gmail. com> wrote:
                                > > I think I will go for a magnetic loop, and got a description where I need 32" of 1" aluminum tube, bent to form a circle, and a coax inside. I will be able to get a coax, but here in Pattaya I have no ideas where to get the aluminium,

                                A bicycle wheel rim is also suitable. While aluminum is preferable, steel will work as well.   Take out the spokes and away you go.

                                http://www.aa5tb.com/loop.html
                              • Sid Boyce
                                ... Many guys seem to shy away from magnetic loops. I don t why as they are easy to make, they don t need height and they work splendidly. Repeating myself, my
                                Message 15 of 15 , Nov 26, 2012
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                                  On 26/11/12 14:21, Tom Clifton wrote:
                                   
                                  > On 25 Nov 2012, at 18:54, Ulf Holt Gmail <ulf.holt@gmail. com> wrote:
                                  > > I think I will go for a magnetic loop, and got a description where I need 32" of 1" aluminum tube, bent to form a circle, and a coax inside. I will be able to get a coax, but here in Pattaya I have no ideas where to get the aluminium,

                                  A bicycle wheel rim is also suitable. While aluminum is preferable, steel will work as well.   Take out the spokes and away you go.

                                  Many guys seem to shy away from magnetic loops. I don't why as they are easy to make, they don't need height and they work splendidly.

                                  Repeating myself, my first was made of 3/8" diameter soft copper tuned with a variable capacitor that was only capable of 7W before it would arc over and placed indoors on the upstairs landing I worked all over Europe with it on 40m. Within less than an hour this loop was built and working. I used the small coupling loop with this one.

                                  My present loop is 8' diameter octal with 22mm copper pipe and 45 degree copper elbows tuned with a vacuum capacitor that takes the full 100W.

                                  The one being rebuilt after it crashed in 60+ mph winds is a 13' diameter of 28mm copper tube constructed with 45 degree elbows as the current one. With this one and 100W all my 80m contacts Stateside have been made with good reports both ways.

                                  The aa5tb loop page also has pointers to many more magnetic loop information sources.

                                  BTW I have found gamma matching for me has been easier than trying to adjust the small coupling loop.

                                  You can't beat magnetic loops for ease of construction and operating.
                                  73 ... Sid.
                                  -- 
                                  Sid Boyce ... Hamradio License G3VBV, Licensed Private Pilot
                                  Emeritus IBM/Amdahl Mainframes and Sun/Fujitsu Servers Tech Support
                                  Senior Staff Specialist, Cricket Coach
                                  Microsoft Windows Free Zone - Linux used for all Computing Tasks
                                  
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