Loading ...
Sorry, an error occurred while loading the content.
 

Ultra Cheap RX Dongle for monitor stations

Expand Messages
  • graham787
    All In support of requests for monitor stations , Listed are a set of links to enable the £5 usb dongle to be used as SDR-RX , it will benefit
    Message 1 of 5 , Aug 27, 2013
      All

      In support of requests for monitor stations ,

      Listed are a set of links to enable the £5 usb dongle to be used as SDR-RX , it will benefit from preselectors / filters / pre-amps etc , but the initial out lay of £5 is minimal compared to the results and quality of the supporting software is excellent , as well as the SDR )

      Performance on HF is 'good' and benefits from a ATU or better a pre-selector , The later dongle will cover 1500 MHz down to 24MHz directly

      A modification is needed to access the direct sample mode , attaching a wire and cap .. the video listed is using the wire+cap method , alternative is to use a transformer , taking care the core is rated at the band is question

      MF and down , the 'gain' falls off , I have good results using the 500k tx-atu , the Mini-whip Ae seem's to offer a reasonable solution , and can be seen operating > http://myweb.tiscali.co.uk/wgtaylor/grabber2.html

      73-Graham,


      SDR >>http://sdrsharp.com/


      Mods>>http://www.rtl-sdr.com/rtl-sdr-direct-sampling-mode/


      7MHz ssb>>http://www.youtube.com/watch?v=7Le-1aW9BR4


      Virtual audio cable >>http://vb-audio.pagesperso-orange.fr/Cable/index.htm
    • Andy Talbot
      Yes... Glad its not just me. I noticed gain fell off considerably at low frequencies - was begining to suspect my transformer at first. There s something
      Message 2 of 5 , Aug 27, 2013
        Yes...   Glad its not just me.   I noticed gain fell off considerably at low frequencies - was begining to suspect my transformer at first.  There's something very odd going on with those dongles.  The main chip doesn't seem to take in baseband - it is as if it does an IF sampling job on a 28MHz input, since input at higher HF works OK, and an input at 28MHz behaves as if it were at zero frequency - classic alliasing in fact.
         
        Could it have in internal high pass filter specifically for first allias sampling ?
         
        I've been unable to lay my hands on a full data sheet for the Realtek chip so have no explanation for what its actually doing  
         
        All pointers / data sheets greatfully received :-)
         
        Andy
        G4JNT


        On 27 August 2013 14:24, graham787 <g0nbd@...> wrote:
         

        All

        In support of requests for monitor stations ,

        Listed are a set of links to enable the £5 usb dongle to be used as SDR-RX , it will benefit from preselectors / filters / pre-amps etc , but the initial out lay of £5 is minimal compared to the results and quality of the supporting software is excellent , as well as the SDR )

        Performance on HF is 'good' and benefits from a ATU or better a pre-selector , The later dongle will cover 1500 MHz down to 24MHz directly

        A modification is needed to access the direct sample mode , attaching a wire and cap .. the video listed is using the wire+cap method , alternative is to use a transformer , taking care the core is rated at the band is question

        MF and down , the 'gain' falls off , I have good results using the 500k tx-atu , the Mini-whip Ae seem's to offer a reasonable solution , and can be seen operating > http://myweb.tiscali.co.uk/wgtaylor/grabber2.html

        73-Graham,

        SDR >>http://sdrsharp.com/

        Mods>>http://www.rtl-sdr.com/rtl-sdr-direct-sampling-mode/

        7MHz ssb>>http://www.youtube.com/watch?v=7Le-1aW9BR4

        Virtual audio cable >>http://vb-audio.pagesperso-orange.fr/Cable/index.htm


      • siegfried jackstien
        I do not know if that is the case (so just a guessing!!) ... what if the sampling chip has an internal pll that is locked to the 28.8 external clock but
        Message 3 of 5 , Aug 27, 2013
          I do not know if that is the case (so just a guessing!!) ... what if the
          sampling chip has an internal pll that is "locked" to the 28.8 external
          clock but works with a higher clock rate (maybe 57.6 mhz or even higher)

          On the realtek hp they CLAIM that the chip can also work with an if of 36
          megs .... so I am guessing that there is some "magical clock divider" in the
          chip ... otherwise the chip could not work with input of 36 megs (or only
          with lots of ghost signals)

          Sadly realtek gives no further info about whats going on in that chip

          Dg9bfc

          Sigi

          Ps a friend found a preamp ... 50ohms in and 200 ohms symmetrical out ...
          and uses that for direct sampling instead using a balun



          > -----Ursprüngliche Nachricht-----
          > Von: O_P_E_R_A_@yahoogroups.com [mailto:O_P_E_R_A_@yahoogroups.com] Im
          > Auftrag von Andy Talbot
          > Gesendet: Dienstag, 27. August 2013 13:34
          > An: O_P_E_R_A_@yahoogroups.com
          > Betreff: Re: [O_P_E_R_A_] Ultra Cheap RX Dongle for monitor stations
          >
          >
          >
          > Yes... Glad its not just me. I noticed gain fell off considerably at
          > low frequencies - was begining to suspect my transformer at first.
          > There's something very odd going on with those dongles. The main chip
          > doesn't seem to take in baseband - it is as if it does an IF sampling job
          > on a 28MHz input, since input at higher HF works OK, and an input at 28MHz
          > behaves as if it were at zero frequency - classic alliasing in fact.
          >
          > Could it have in internal high pass filter specifically for first allias
          > sampling ?
          >
          > I've been unable to lay my hands on a full data sheet for the Realtek chip
          > so have no explanation for what its actually doing
          >
          > All pointers / data sheets greatfully received :-)
          >
          > Andy
          > G4JNT
          >
          >
          >
          > On 27 August 2013 14:24, graham787 <g0nbd@...> wrote:
          >
          >
          >
          >
          >
          > All
          >
          > In support of requests for monitor stations ,
          >
          > Listed are a set of links to enable the £5 usb dongle to be used as
          > SDR-RX , it will benefit from preselectors / filters / pre-amps etc , but
          > the initial out lay of £5 is minimal compared to the results and quality
          > of the supporting software is excellent , as well as the SDR )
          >
          > Performance on HF is 'good' and benefits from a ATU or better a pre-
          > selector , The later dongle will cover 1500 MHz down to 24MHz directly
          >
          > A modification is needed to access the direct sample mode ,
          > attaching a wire and cap .. the video listed is using the wire+cap method
          > , alternative is to use a transformer , taking care the core is rated at
          > the band is question
          >
          > MF and down , the 'gain' falls off , I have good results using the
          > 500k tx-atu , the Mini-whip Ae seem's to offer a reasonable solution , and
          > can be seen operating > http://myweb.tiscali.co.uk/wgtaylor/grabber2.html
          >
          > 73-Graham,
          >
          > SDR >>http://sdrsharp.com/
          >
          > Mods>>http://www.rtl-sdr.com/rtl-sdr-direct-sampling-mode/
          >
          > 7MHz ssb>>http://www.youtube.com/watch?v=7Le-1aW9BR4
          >
          > Virtual audio cable >>http://vb-audio.pagesperso-
          > orange.fr/Cable/index.htm
          >
          >
          >
          >
          >
        • graham787
          Yes , there not quite as expected , the fall off was mentioned some time ago in the google group, I just used the wire+cap method , that produces
          Message 4 of 5 , Aug 27, 2013
            Yes , there not quite as expected , the fall off was mentioned some time ago in the google group, I just used the wire+cap method , that produces acceptable results and for £4,50p very hi

            Sigi uses a balanced input , problem there could be the core working from 5/10KH to 22 Mhz , but as long as you have some form of tuner/filter etc results are quite acceptable , adding all those mixers and oscillators , never did strike me as being the best way to the low bands

            Main thing is , with the on set of winter , one of these and a small pc or old lap top and you have a monitor , there not locked and 100% stable , but , the AFC in Opera ( and Ros MF ) is more than a match ..

            G,



            --- In O_P_E_R_A_@yahoogroups.com, Andy Talbot <andy.g4jnt@...> wrote:
            >
            > Yes... Glad its not just me. I noticed gain fell off considerably at
            > low frequencies - was begining to suspect my transformer at first. There's
            > something very odd going on with those dongles. The main chip doesn't seem
            > to take in baseband - it is as if it does an IF sampling job on a 28MHz
            > input, since input at higher HF works OK, and an input at 28MHz behaves as
            > if it were at zero frequency - classic alliasing in fact.
            >
            > Could it have in internal high pass filter specifically for first allias
            > sampling ?
            >
            > I've been unable to lay my hands on a full data sheet for the Realtek chip
            > so have no explanation for what its actually doing
            >
            > All pointers / data sheets greatfully received :-)
            >
            > Andy
            > G4JNT
            >
            >
            > On 27 August 2013 14:24, graham787 <g0nbd@...> wrote:
            >
            > > **
            > >
            > >
            > > All
            > >
            > > In support of requests for monitor stations ,
            > >
            > > Listed are a set of links to enable the £5 usb dongle to be used as SDR-RX
            > > , it will benefit from preselectors / filters / pre-amps etc , but the
            > > initial out lay of £5 is minimal compared to the results and quality of the
            > > supporting software is excellent , as well as the SDR )
            > >
            > > Performance on HF is 'good' and benefits from a ATU or better a
            > > pre-selector , The later dongle will cover 1500 MHz down to 24MHz directly
            > >
            > > A modification is needed to access the direct sample mode , attaching a
            > > wire and cap .. the video listed is using the wire+cap method , alternative
            > > is to use a transformer , taking care the core is rated at the band is
            > > question
            > >
            > > MF and down , the 'gain' falls off , I have good results using the 500k
            > > tx-atu , the Mini-whip Ae seem's to offer a reasonable solution , and can
            > > be seen operating > http://myweb.tiscali.co.uk/wgtaylor/grabber2.html
            > >
            > > 73-Graham,
            > >
            > > SDR >>http://sdrsharp.com/
            > >
            > > Mods>>http://www.rtl-sdr.com/rtl-sdr-direct-sampling-mode/
            > >
            > > 7MHz ssb>>http://www.youtube.com/watch?v=7Le-1aW9BR4
            > >
            > > Virtual audio cable >>http://vb-audio.pagesperso-orange.fr/Cable/index.htm
            > >
            > >
            > >
            >
          • graham787
            Sigi You could ask on the google sdr site , some there seem to have the details of the chips
            Message 5 of 5 , Aug 27, 2013
              Sigi

              You could ask on the google sdr site , some there seem to have the details of the chips

              https://groups.google.com/forum/?fromgroups#!forum/ultra-cheap-sdr

              Have you details for this ?:-

              Ps a friend found a preamp ... 50ohms in and 200 ohms symmetrical out ...> and uses that for direct sampling instead using a balun

              Tnx-G,


              --- In O_P_E_R_A_@yahoogroups.com, "siegfried jackstien" <siegfried.jackstien@...> wrote:
              >
              > I do not know if that is the case (so just a guessing!!) ... what if the
              > sampling chip has an internal pll that is "locked" to the 28.8 external
              > clock but works with a higher clock rate (maybe 57.6 mhz or even higher)
              >
              > On the realtek hp they CLAIM that the chip can also work with an if of 36
              > megs .... so I am guessing that there is some "magical clock divider" in the
              > chip ... otherwise the chip could not work with input of 36 megs (or only
              > with lots of ghost signals)
              >
              > Sadly realtek gives no further info about whats going on in that chip
              >
              > Dg9bfc
              >
              > Sigi
              >
              > Ps a friend found a preamp ... 50ohms in and 200 ohms symmetrical out ...
              > and uses that for direct sampling instead using a balun
              >
              >
              >
              > > -----Ursprüngliche Nachricht-----
              > > Von: O_P_E_R_A_@yahoogroups.com [mailto:O_P_E_R_A_@yahoogroups.com] Im
              > > Auftrag von Andy Talbot
              > > Gesendet: Dienstag, 27. August 2013 13:34
              > > An: O_P_E_R_A_@yahoogroups.com
              > > Betreff: Re: [O_P_E_R_A_] Ultra Cheap RX Dongle for monitor stations
              > >
              > >
              > >
              > > Yes... Glad its not just me. I noticed gain fell off considerably at
              > > low frequencies - was begining to suspect my transformer at first.
              > > There's something very odd going on with those dongles. The main chip
              > > doesn't seem to take in baseband - it is as if it does an IF sampling job
              > > on a 28MHz input, since input at higher HF works OK, and an input at 28MHz
              > > behaves as if it were at zero frequency - classic alliasing in fact.
              > >
              > > Could it have in internal high pass filter specifically for first allias
              > > sampling ?
              > >
              > > I've been unable to lay my hands on a full data sheet for the Realtek chip
              > > so have no explanation for what its actually doing
              > >
              > > All pointers / data sheets greatfully received :-)
              > >
              > > Andy
              > > G4JNT
              > >
              > >
              > >
              > > On 27 August 2013 14:24, graham787 <g0nbd@...> wrote:
              > >
              > >
              > >
              > >
              > >
              > > All
              > >
              > > In support of requests for monitor stations ,
              > >
              > > Listed are a set of links to enable the £5 usb dongle to be used as
              > > SDR-RX , it will benefit from preselectors / filters / pre-amps etc , but
              > > the initial out lay of £5 is minimal compared to the results and quality
              > > of the supporting software is excellent , as well as the SDR )
              > >
              > > Performance on HF is 'good' and benefits from a ATU or better a pre-
              > > selector , The later dongle will cover 1500 MHz down to 24MHz directly
              > >
              > > A modification is needed to access the direct sample mode ,
              > > attaching a wire and cap .. the video listed is using the wire+cap method
              > > , alternative is to use a transformer , taking care the core is rated at
              > > the band is question
              > >
              > > MF and down , the 'gain' falls off , I have good results using the
              > > 500k tx-atu , the Mini-whip Ae seem's to offer a reasonable solution , and
              > > can be seen operating > http://myweb.tiscali.co.uk/wgtaylor/grabber2.html
              > >
              > > 73-Graham,
              > >
              > > SDR >>http://sdrsharp.com/
              > >
              > > Mods>>http://www.rtl-sdr.com/rtl-sdr-direct-sampling-mode/
              > >
              > > 7MHz ssb>>http://www.youtube.com/watch?v=7Le-1aW9BR4
              > >
              > > Virtual audio cable >>http://vb-audio.pagesperso-
              > > orange.fr/Cable/index.htm
              > >
              > >
              > >
              > >
              > >
              >
            Your message has been successfully submitted and would be delivered to recipients shortly.