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Re: [softrock40] Antenna problems?

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  • Alan
    Ulf, http://websdr.ewi.utwente.nl:8901/ ? This is mounted on top of the building. A quick search:- When you place this tiny antenna outside the house (!), it
    Message 1 of 12 , Nov 19, 2012
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      Ulf,

      http://websdr.ewi.utwente.nl:8901/ ?

      This is mounted on top of the building.
      A quick search:- "When you place this tiny antenna outside the house (!), it will perform like a full-sized antenna for the VLF and
      shortwave bands."

      It is , as far as I can see, dependent on being placed away from interference sources. Then the amplified signal fed to the
      receiver.
      I find antennas like this work well on LF. But mine are 30m away from any building. Mounted close they are ineffective, picking up
      noise from many sources.

      You need something with minimal response to interference.

      73 Alan G4ZFQ


      ----- Original Message -----
      From: "Ulf Holt Gmail" <ulf.holt@...>
      To: <softrock40@yahoogroups.com>
      Sent: Monday, November 19, 2012 6:18 AM
      Subject: Re: [softrock40] Antenna problems?


      I have been informed by a Norwegian Amateur about a mini antenna Pa0rdt-mini-whip, which sounds interesting, there is an URL to a
      SDR radio using this antenna? Http://Webster.ewi.utwente.nl:8901 and it was impressing what this little mini antenna could do. This
      is, of course, an antenna for RX only, so I will give it a go. Anyone out there with experience?


      > There are a number of DOS and Windows loop calculation applications like mloop31, loopcalc.exe, RJELOOP1, etc. available via a
      > search engine.
      > With the programs you can model a loop - by providing loop size (total length), diameter of coax and frequency it will give values
      > of capacitors, etc.
      >
      > Online loop calculator http://www.66pacific.com/calculators/small_tx_loop_calc.aspx
      >
      > RG213 is best as the self capacitance is much less than RG58 and higher Q.
      >
      > Also practical articles - so many as to make your head spin.
      > http://www.rsars.org.uk/ELIBRARY/ANTENNAS%20DOCS/Portable%20HF%20Loop%20%2040-10m%20-%20G8ODE%20iss%201.3%20.pdf
      >
      > http://newsgroups.derkeiler.com/Archive/Rec/rec.radio.amateur.antenna/2006-08/msg00069.html
      >
      > I am sure you can build a loop that's easily transportable to cover all HF bands 40m - 10m.
      >
    • vbifyz
      My tuned loop is a hula-hoop about 1m diameter with 14ga wire threaded through it. You don t have to use coax, any round wire will do. The variable capacitor
      Message 2 of 12 , Nov 19, 2012
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        My tuned loop is a hula-hoop about 1m diameter with 14ga wire threaded through it. You don't have to use coax, any round wire will do. The variable capacitor is from an old radio, 2 sections about 400pF max each. I tied it with cable ties to the loop and added a switch to flip between a single section and 2 sections in parallel. The coupling loop is about 20cm diameter.
        It does not give the optimum signal level for the Softrock, but in a high noise situation such loop allows to hear many more signals than any wire contraption. The tuning range is from 3.5MHz to about 15-16MHz.
        I tried PA0RDT mini-whip as well and didn't see any noise rejecting properties compared to a random wire.

        73, Mike

        --- In softrock40@yahoogroups.com, Ulf Holt Gmail <ulf.holt@...> wrote:
        >
        > I will try this construction, but I have a few questions.
        > 1) what dimensions are we talking about?
        > 2) how large capacitor and do I have to pick a frequency on the receiver and then go back to the antenna and tune the capacitor, for the optimal signal? As it is now, I can't hear any signals at all.
        > 3) what kind of coax? The only coax I could get my hands on here is 60 ohm coax for surveillance cameras, which i had to use for feeding the receiver,but off course when I go to Bangkok later this week, I can get whatever I want. I suppose RG213 would be a possible choice. RG58 is too soft if the ring has a diameter larger 20 - 30 cm. maybe I should replace the feeder, using RG58 instead?
        >
        > Ulf
        >
        >
        >
        > Sendt fra min iPad
        >
        > Den 19. nov. 2012 kl. 04:29 skrev "junius fox" <jfox05@...>:
        >
        > > Hello, You can construct a nice receiving antenna out of coax and a inexpensive plastic variable that are used in cheap radios.
        > > the antenna is shown below:
        > >
        > >
        > > ----- Original Message -----
        > > From: Ulf Holt
        > > To: softrock40@yahoogroups.com
        > > Sent: Sunday, November 18, 2012 2:44 AM
        > > Subject: [softrock40] Antenna problems?
        > >
        > >
        > > As I have mentioned in my request for Software (I have now choosen to use PowerSDR-iq) I have problems reveiving anything. I got a Chinese AM station the other day, so I suppose the RX Ensemble II receiver is working in some way or another, but I am not very impressed of the sensivity. My problem is how to put up an antenna to test this radio.
        > >
        > > I am on a long vaccation in Thailand, and we live on second flor in a building that is 18 flors, and the only chanse for me is a balcony which is not very large and east bound. To make things even worse, both sides are shielded with concrete, so I only have an free opening that is about 1.8 m x 4 m. I tried to put up a simple wire about 4 meter long, and connected it to the inner cord of a coax, which I connected to the receiver. A really bad solution, but I still would expect to pick up something, but I cannot get anything at all. If I remove the antenna, I can heare a difference, the noise level is falling, but that's about it.
        > >
        > > Any bright ideas out there?
        > >
        > > 73 de LA2SL
        > >
        > > Ulf
        > >
        >
      • Zack Widup
        This looks like the AMRAD E-probe antenna. It s a great antenna used extensively by the LOWFer community. The only thing is that in order to get the best
        Message 3 of 12 , Nov 19, 2012
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          This looks like the AMRAD E-probe antenna. It's a great antenna used extensively by the LOWFer community. The only thing is that in order to get the best performance from it, it has to be mounted higher than any objects nearby, including trees. It receives the E-field which is a function of elevation and is greatly attenuated by higher objects such as buildings, towers and trees.

          http://tinyurl.com/cj8eday

          Also, there are modifications of this circuit to replace the CP666 FET with a J310.

          73, Zack W9SZ


          On Mon, Nov 19, 2012 at 2:00 AM, Alan <alan4alan@...> wrote:
           

          Ulf,

          http://websdr.ewi.utwente.nl:8901/ ?

          This is mounted on top of the building.
          A quick search:- "When you place this tiny antenna outside the house (!), it will perform like a full-sized antenna for the VLF and
          shortwave bands."

          It is , as far as I can see, dependent on being placed away from interference sources. Then the amplified signal fed to the
          receiver.
          I find antennas like this work well on LF. But mine are 30m away from any building. Mounted close they are ineffective, picking up
          noise from many sources.

          You need something with minimal response to interference.

          73 Alan G4ZFQ



          ----- Original Message -----
          From: "Ulf Holt Gmail" <ulf.holt@...>
          To: <softrock40@yahoogroups.com>
          Sent: Monday, November 19, 2012 6:18 AM
          Subject: Re: [softrock40] Antenna problems?

          I have been informed by a Norwegian Amateur about a mini antenna Pa0rdt-mini-whip, which sounds interesting, there is an URL to a
          SDR radio using this antenna? Http://Webster.ewi.utwente.nl:8901 and it was impressing what this little mini antenna could do. This
          is, of course, an antenna for RX only, so I will give it a go. Anyone out there with experience?

          > There are a number of DOS and Windows loop calculation applications like mloop31, loopcalc.exe, RJELOOP1, etc. available via a
          > search engine.
          > With the programs you can model a loop - by providing loop size (total length), diameter of coax and frequency it will give values
          > of capacitors, etc.
          >
          > Online loop calculator http://www.66pacific.com/calculators/small_tx_loop_calc.aspx
          >
          > RG213 is best as the self capacitance is much less than RG58 and higher Q.
          >
          > Also practical articles - so many as to make your head spin.
          > http://www.rsars.org.uk/ELIBRARY/ANTENNAS%20DOCS/Portable%20HF%20Loop%20%2040-10m%20-%20G8ODE%20iss%201.3%20.pdf
          >
          > http://newsgroups.derkeiler.com/Archive/Rec/rec.radio.amateur.antenna/2006-08/msg00069.html
          >
          > I am sure you can build a loop that's easily transportable to cover all HF bands 40m - 10m.
          >


        • cbayona
          Even better is a shielded loop like suggested a few days ago, the noise fighting capabilities on the low bands is fantastic. I have one and the noise from
          Message 4 of 12 , Nov 19, 2012
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            Even better is a shielded loop like suggested a few days ago, the
            noise fighting capabilities on the low bands is fantastic.

            I have one and the noise from computers and related items
            went better than S9+10dB to .5 dB, I have 8 PCs and related gear
            and live next to a very noisy mid-voltage line and they bother me not one bit.

            Mine is an untuned loop so no tuning when you change frequency but a
            tuned one has it's advantages, if helps keep other frequencies from
            overloading your SoftRock, but no signals on the panadapter.



            At 09:54 AM 11/19/2012, you wrote:
            >My tuned loop is a hula-hoop about 1m diameter with 14ga wire
            >threaded through it. You don't have to use coax, any round wire will
            >do. The variable capacitor is from an old radio, 2 sections about
            >400pF max each. I tied it with cable ties to the loop and added a
            >switch to flip between a single section and 2 sections in parallel.
            >The coupling loop is about 20cm diameter.
            >It does not give the optimum signal level for the Softrock, but in a
            >high noise situation such loop allows to hear many more signals than
            >any wire contraption. The tuning range is from 3.5MHz to about 15-16MHz.
            >I tried PA0RDT mini-whip as well and didn't see any noise rejecting
            >properties compared to a random wire.
            >
            >73, Mike
            >
            >--- In softrock40@yahoogroups.com, Ulf Holt Gmail <ulf.holt@...> wrote:
            > >
            > > I will try this construction, but I have a few questions.
            > > 1) what dimensions are we talking about?
            > > 2) how large capacitor and do I have to pick a frequency on the
            > receiver and then go back to the antenna and tune the capacitor,
            > for the optimal signal? As it is now, I can't hear any signals at all.
            > > 3) what kind of coax? The only coax I could get my hands on here
            > is 60 ohm coax for surveillance cameras, which i had to use for
            > feeding the receiver,but off course when I go to Bangkok later this
            > week, I can get whatever I want. I suppose RG213 would be a
            > possible choice. RG58 is too soft if the ring has a diameter larger
            > 20 - 30 cm. maybe I should replace the feeder, using RG58 instead?
            > >
            > > Ulf
            > >
            > >
            > >
            > > Sendt fra min iPad
            > >
            > > Den 19. nov. 2012 kl. 04:29 skrev "junius fox" <jfox05@...>:
            > >
            > > > Hello, You can construct a nice receiving antenna out of coax
            > and a inexpensive plastic variable that are used in cheap radios.
            > > > the antenna is shown below:
            > > >
            > > >
            > > > ----- Original Message -----
            > > > From: Ulf Holt
            > > > To: softrock40@yahoogroups.com
            > > > Sent: Sunday, November 18, 2012 2:44 AM
            > > > Subject: [softrock40] Antenna problems?
            > > >
            > > >
            > > > As I have mentioned in my request for Software (I have now
            > choosen to use PowerSDR-iq) I have problems reveiving anything. I
            > got a Chinese AM station the other day, so I suppose the RX
            > Ensemble II receiver is working in some way or another, but I am
            > not very impressed of the sensivity. My problem is how to put up an
            > antenna to test this radio.
            > > >
            > > > I am on a long vaccation in Thailand, and we live on second
            > flor in a building that is 18 flors, and the only chanse for me is
            > a balcony which is not very large and east bound. To make things
            > even worse, both sides are shielded with concrete, so I only have
            > an free opening that is about 1.8 m x 4 m. I tried to put up a
            > simple wire about 4 meter long, and connected it to the inner cord
            > of a coax, which I connected to the receiver. A really bad
            > solution, but I still would expect to pick up something, but I
            > cannot get anything at all. If I remove the antenna, I can heare a
            > difference, the noise level is falling, but that's about it.
            > > >
            > > > Any bright ideas out there?
            > > >
            > > > 73 de LA2SL
            > > >
            > > > Ulf
            > > >
            > >

            --
            Cecil - k5nwa
            http://www.softrockradio.org/ http://thepartsplace.k5nwa.com/

            Never take life seriously. Nobody gets out alive anyway.
          • Sid Boyce
            The mini-whip seems excellent covering all HF bands. I ve tuned in to a number on the internet connected to Softrocks and other rigs using QtRadio on PC s and
            Message 5 of 12 , Nov 19, 2012
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              The mini-whip seems excellent covering all HF bands.
              I've tuned in to a number on the internet connected to Softrocks and other rigs using QtRadio on PC's and ARM boxes and glSDR on my Android phone.
              73 ... Sid.

              On 19/11/12 06:18, Ulf Holt Gmail wrote:
               
              I have been informed by a Norwegian Amateur about a mini antenna Pa0rdt-mini-whip, which sounds interesting, there is an URL to a SDR radio using this antenna? Http://Webster.ewi.utwente.nl:8901 and it was impressing what this little mini antenna could do. This is, of course, an antenna for RX only, so I will give it a go. Anyone out there with experience?

              Ulf

              Sendt fra min iPad

              Den 19. nov. 2012 kl. 07:45 skrev Sid Boyce <sboyce@...>:

               

              There are a number of DOS and Windows loop calculation applications like mloop31, loopcalc.exe, RJELOOP1,  etc. available via a search engine.
              With the programs you can model a loop - by providing loop size (total length), diameter of coax and frequency it will give values of capacitors, etc.

              Online loop calculator http://www.66pacific.com/calculators/small_tx_loop_calc.aspx

              RG213 is best as the self capacitance is much less than RG58 and higher Q.  

              Also practical articles - so many as to make your head spin.
              http://www.rsars.org.uk/ELIBRARY/ANTENNAS%20DOCS/Portable%20HF%20Loop%20%2040-10m%20-%20G8ODE%20iss%201.3%20.pdf

              http://newsgroups.derkeiler.com/Archive/Rec/rec.radio.amateur.antenna/2006-08/msg00069.html

              I am sure you can build a loop that's easily transportable to cover all HF bands 40m - 10m.

              If you are using the loop only for RX you can ignore the voltage in the results - the programs ask for TX power and returns the voltage (KV) across the capacitor for the amount of power. The plate spacing for the capacitor is not relevant if RX only.

              My first loop was made from 1m of 3/8" soft copper and I used a capacitor that limited my TX power to 7W SSB and I worked all over Europe on 40m with excellent results with the loop indoors on the upstairs landing.

              You can lean the loop up against a wall or erected in any convenient spot and it doesn't need height.

              Using a gamma match is easier to adjust than a coupling loop and lessens what you have to take with you. I use gamma matching on all my loops from the 1m diameter to the 13 feet diameter.
              73 ... Sid.

              On 18/11/12 23:27, Ulf Holt Gmail wrote:
               
              I will try this construction, but I have a few questions.
              1) what dimensions are we talking about?
              2) how large capacitor and do I have to pick a frequency on the receiver and then go back to the antenna and tune the capacitor, for the optimal signal? As it is now, I can't hear any signals at all.
              3) what kind of coax? The only coax I could get my hands on here is 60 ohm coax for surveillance cameras,  which i had to use for feeding the receiver,but off course when I go to Bangkok later this week, I can get whatever I want. I suppose RG213 would be a possible choice. RG58 is too soft if the ring has a diameter larger 20 - 30 cm. maybe I should replace the feeder, using RG58 instead?

              Ulf



              Sendt fra min iPad

              Den 19. nov. 2012 kl. 04:29 skrev "junius fox" <jfox05@...>:

               

              Hello,  You can construct a nice receiving antenna out of coax and a inexpensive plastic variable that are used in cheap radios.
              the antenna is shown below:
               
              ----- Original Message -----
              From: Ulf Holt
              Sent: Sunday, November 18, 2012 2:44 AM
              Subject: [softrock40] Antenna problems?

               

              As I have mentioned in my request for Software (I have now choosen to use PowerSDR-iq) I have problems reveiving anything. I got a Chinese AM station the other day, so I suppose the RX Ensemble II receiver is working in some way or another, but I am not very impressed of the sensivity. My problem is how to put up an antenna to test this radio.
               
              I am on a long vaccation in Thailand, and we live on second flor in a building that is 18 flors, and the only chanse for me is a balcony which is not very large and east bound. To make things even worse, both sides are shielded with concrete, so I only have an free opening that is about 1.8 m x 4 m.  I tried to put up a simple wire about 4 meter long, and connected it to the inner cord of a coax, which I connected to the receiver. A really bad solution, but I still would expect to pick up something, but I cannot get anything at all. If I remove the antenna, I can heare a difference, the noise level is falling, but that's about it.
               
              Any bright ideas out there?
               
              73 de LA2SL
               
              Ulf


              -- 
              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
              


              -- 
              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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