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USB galvanic isolator

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  • e12bf134c86b4469fbc839a30223405d
    Good afternoon ! Has anyone in use a usb galvanic isolator - in line between receiver and computer? Will it decrease noise level or its unuseful?
    Message 1 of 15 , Jan 30, 2014
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      Good afternoon !


      Has anyone in  use a "usb galvanic isolator" - in line between receiver and computer? Will it decrease noise level or its unuseful? 
    • andrea montefusco
      Topic already discussed many times, for example here: https://groups.yahoo.com/neo/groups/perseus_SDR/conversations/topics/18814 ... -- Andrea Montefusco
      Message 2 of 15 , Mar 19, 2014
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        Topic already discussed many times, for example here:

        https://groups.yahoo.com/neo/groups/perseus_SDR/conversations/topics/18814


        On Thu, Jan 30, 2014 at 10:41 PM, <astaroth120@...> wrote:

        Has anyone in  use a "usb galvanic isolator" - in line between receiver and computer? Will it decrease noise level or its unuseful? 

         

        --
        Andrea Montefusco IW0HDV
        ------------------------------------------
        As my old boss, an Apollo veteran, would often remind us “It’s good to be smart, but it’s better to be lucky.”
           Wayne Hale, Space Shuttle Flight Director
      • Karel Honzík
        A strange thing happened with my Perseus this morning. Perhaps, first of all, I should put a question: is there a device in the Perseus box which can
        Message 3 of 15 , Apr 9, 2014
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          A strange thing happened with my Perseus this morning. Perhaps, first of all, I should put a question: is there a device in the Perseus box which can disconnect the ground in certain (dangerous?) situations?
           
          This morning, under strong and constant windy conditions (perhaps it was important) unusual in this location I was observing signals suddenly disappearing in noise. It was not a faulty antenna connection, the S-meter was showing the same strength, it was asuddenly increasing noise level. Exactly like there was no ground at the moment – the same level and character of noise. To reduce a number of places where it could occur I changed connectors, adapters, I even cut a short piece of coax cable and screwed a new F-connector on it. Nothing helped and time to time the ground was disappearing again and again.
           
          It was interesting that it was happening on my Longwire antenna with a balun only. No such problem on the MiniWhip active antenna.
           
          Then I found out what helps: when I pull the antenna off and plug in again. Then the signal is OK ... until it falls off again after a minute or so (this OK period was never longer than 5 minutes).
           
          So I was wondering – was the strange behaviour of Perseus in connection with the 70m longwire antenna, a strong and constant wind, statics, balun...?
           
          But I must repeat: Perseus works with the MiniWhip antenna without problems and is excellent as ever!
           
          Just before this happened I was observing another unusual behaviour of Perseus: during my recording the spectrum curves started to statter and after a while they completely stopped. There was no sound heard at that moment. Never saw this before on my Intel i7 2.90GHz laptop.
           
          Unfortunately, what I miss is the theoretical technical knowledge in this field but there is surely a number of people in this Perseus community with similar experience or knowledge.
           
          Thank you very much,
          Karel
        • Roberto Zinelli
          Hello Karel, when the problem occur you notice the clip led on? 73 Roberto ... Hello Karel, when the problem occur you notice the clip led on? 73 Roberto On
          Message 4 of 15 , Apr 9, 2014
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            Hello Karel,  when the problem occur you notice the clip led on? 

            73 Roberto


            On Wed, Apr 9, 2014 at 10:34 PM, Karel Honzík <RadioRevue@...> wrote:
             

            A strange thing happened with my Perseus this morning. Perhaps, first of all, I should put a question: is there a device in the Perseus box which can disconnect the ground in certain (dangerous?) situations?
             
            This morning, under strong and constant windy conditions (perhaps it was important) unusual in this location I was observing signals suddenly disappearing in noise. It was not a faulty antenna connection, the S-meter was showing the same strength, it was asuddenly increasing noise level. Exactly like there was no ground at the moment – the same level and character of noise. To reduce a number of places where it could occur I changed connectors, adapters, I even cut a short piece of coax cable and screwed a new F-connector on it. Nothing helped and time to time the ground was disappearing again and again.
             
            It was interesting that it was happening on my Longwire antenna with a balun only. No such problem on the MiniWhip active antenna.
             
            Then I found out what helps: when I pull the antenna off and plug in again. Then the signal is OK ... until it falls off again after a minute or so (this OK period was never longer than 5 minutes).
             
            So I was wondering – was the strange behaviour of Perseus in connection with the 70m longwire antenna, a strong and constant wind, statics, balun...?
             
            But I must repeat: Perseus works with the MiniWhip antenna without problems and is excellent as ever!
             
            Just before this happened I was observing another unusual behaviour of Perseus: during my recording the spectrum curves started to statter and after a while they completely stopped. There was no sound heard at that moment. Never saw this before on my Intel i7 2.90GHz laptop.
             
            Unfortunately, what I miss is the theoretical technical knowledge in this field but there is surely a number of people in this Perseus community with similar experience or knowledge.
             
            Thank you very much,
            Karel


          • Jurgen Bartels
            ... Karel, it seems you have the noise-blanker still on with its level set too high. Turn it off. Jurgen Bartels Suellwarden, N. Germany Ant. hor: 29-45MHz
            Message 5 of 15 , Apr 9, 2014
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              > A strange thing happened with my Perseus this morning. Perhaps, first of all,
              > I should put a question: is there a device in the Perseus box which can
              > disconnect the ground in certain (dangerous?) situations?
              > This morning, under strong and constant windy conditions (perhaps it was
              > important) unusual in this location I was observing signals suddenly
              > disappearing in noise. It was not a faulty antenna connection, the S-meter was
              > showing the same strength, it was asuddenly increasing noise level. Exactly
              > like there was no ground at the moment - the same level and character of

              Karel, it seems you have the noise-blanker still on with its level set too
              high. Turn it off.



              Jurgen Bartels Suellwarden, N. Germany
              Ant. hor: 29-45MHz 7-el, 45-87MHz 11-el, FM 15.11, Band-3:13-el, UHF:48-el
              TV: Winradio G305 / Fly2000 + video noise filter & variable IF BW
              FM: Downconverter + Perseus + Speclab as WFM demod.
              MW: 30 x 4m EWE 320° with JB-terminator, Winradio & Perseus
              http://zeiterfassung.3sdesign.de/station_list.htm
              http://dx.3sdesign.de/tv_offset_list.htm
            • Karel Honzík
              Roberto, I did not notice the Clip LED on. I cannot reproduce it this morning, the longwire antenna works OK. The strong wind is over (if it was important in
              Message 6 of 15 , Apr 9, 2014
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                Roberto,
                I did not notice the Clip LED on. I cannot reproduce it this morning, the longwire antenna works OK. The strong wind is over (if it was important in this case).
                 
                Thanks,
                Karel
                 
                 
                Sent: Wednesday, April 09, 2014 10:41 PM
                Subject: Re: [perseus_SDR] Strange behaviour of Perseus
                 
                 

                Hello Karel,  when the problem occur you notice the clip led on? 
                 
                73 Roberto


                On Wed, Apr 9, 2014 at 10:34 PM, Karel Honzík <RadioRevue@...> wrote:
                 
                A strange thing happened with my Perseus this morning. Perhaps, first of all, I should put a question: is there a device in the Perseus box which can disconnect the ground in certain (dangerous?) situations?
                 
                This morning, under strong and constant windy conditions (perhaps it was important) unusual in this location I was observing signals suddenly disappearing in noise. It was not a faulty antenna connection, the S-meter was showing the same strength, it was asuddenly increasing noise level. Exactly like there was no ground at the moment – the same level and character of noise. To reduce a number of places where it could occur I changed connectors, adapters, I even cut a short piece of coax cable and screwed a new F-connector on it. Nothing helped and time to time the ground was disappearing again and again.
                 
                It was interesting that it was happening on my Longwire antenna with a balun only. No such problem on the MiniWhip active antenna.
                 
                Then I found out what helps: when I pull the antenna off and plug in again. Then the signal is OK ... until it falls off again after a minute or so (this OK period was never longer than 5 minutes).
                 
                So I was wondering – was the strange behaviour of Perseus in connection with the 70m longwire antenna, a strong and constant wind, statics, balun...?
                 
                But I must repeat: Perseus works with the MiniWhip antenna without problems and is excellent as ever!
                 
                Just before this happened I was observing another unusual behaviour of Perseus: during my recording the spectrum curves started to statter and after a while they completely stopped. There was no sound heard at that moment. Never saw this before on my Intel i7 2.90GHz laptop.
                 
                Unfortunately, what I miss is the theoretical technical knowledge in this field but there is surely a number of people in this Perseus community with similar experience or knowledge.
                 
                Thank you very much,
                Karel
                 
              • Karel Honzík
                Jürgen, the NB was not on. I checked all settings during my troubleshooting. Thanks, Karel From: Jurgen Bartels Sent: Thursday, April 10, 2014 1:05 AM To:
                Message 7 of 15 , Apr 9, 2014
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                  Jürgen,
                  the NB was not on. I checked all settings during my troubleshooting.
                   
                  Thanks,
                  Karel
                   
                   
                  Sent: Thursday, April 10, 2014 1:05 AM
                  Subject: Re: [perseus_SDR] Strange behaviour of Perseus
                   
                   


                  > A strange thing happened with my Perseus this morning. Perhaps,
                  first of all,
                  > I should put a question: is there a device in the Perseus
                  box which can
                  > disconnect the ground in certain (dangerous?)
                  situations?
                  > This morning, under strong and constant windy conditions
                  (perhaps it was
                  > important) unusual in this location I was observing
                  signals suddenly
                  > disappearing in noise. It was not a faulty antenna
                  connection, the S-meter was
                  > showing the same strength, it was asuddenly
                  increasing noise level. Exactly
                  > like there was no ground at the moment -
                  the same level and character of

                  Karel, it seems you have the noise-blanker still on with its level set too
                  high. Turn it off.

                  Jurgen Bartels Suellwarden, N. Germany
                  Ant. hor: 29-45MHz 7-el, 45-87MHz 11-el, FM 15.11, Band-3:13-el, UHF:48-el
                  TV: Winradio G305 / Fly2000 + video noise filter & variable IF BW
                  FM: Downconverter + Perseus + Speclab as WFM demod.
                  MW: 30 x 4m EWE 320° with JB-terminator, Winradio & Perseus
                  http://zeiterfassung.3sdesign.de/station_list.htm
                  http://dx.3sdesign.de/tv_offset_list.htm

                • Roelof Bakker
                  Hello Karel, There might have been static build up on the long wire. You can use a bleed resistor of say 100.000 ohm between the longwire and (radio) ground.
                  Message 8 of 15 , Apr 10, 2014
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                    Hello Karel,

                    There might have been static build up on the long wire.
                    You can use a bleed resistor of say 100.000 ohm between the longwire and
                    (radio) ground.
                    This will prevent voltage build up without effecting reception.

                    What happens inside the PERSEUS is difficult to say.
                    I believe that the input has a rf isolating transformer.

                    Best regards,
                    Roelof Bakker
                  • Roelof Bakker
                    Hello all, An even more modest log! 20140409 1925 518 $01U ESA Talinn,EST 1560 20140409 1952 518 $01X TFA Grindavik,ISL 2045
                    Message 9 of 15 , Apr 10, 2014
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                      Hello all,

                      An even more modest log!

                      20140409 1925 518 $01U ESA Talinn,EST 1560
                      20140409 1952 518 $01X TFA Grindavik,ISL 2045
                      20140409 2015 518 $19B LGP Bodo,NOR 1839
                      20140409 2145 518 $03K SVK Kerkyra,GRC 1821
                      20140409 2216 518 $03M 5BA Cyprus,CYP 2970
                      20140409 2235 518 $03P 4XO Haifa,ISR 3307
                      20140409 2335 518 $03V ICI Sellia Marina,ITA 1737
                      20140409 2350 518 $03X EAV Valencia,ESP 1497
                      20140410 0019 518 $19C LGV Vardo,NOR 2527
                      20140410 0036 518 $03D TAH Istanbul,TUR 2205
                      20140410 0046 518 $03E TAF Samsun,TUR 2727
                      20140410 0058 518 $02F CTH Sao Miguel,AZR 2736
                      20140410 0131 518 $03J LZW Varna,BUL 1997
                      20140410 0216 518 $03O 9HD Malta,MLT 1977


                      Best regards,
                      Roelof
                      ============================================
                      From: Roelof Bakker, pa0rdt
                      Location: Middelburg, Zealand SW Netherlands
                      51 30 02 N, 03 36 02 E, Locator: JO11tm
                      Receiver 1:
                      Afedri SDR, running under SDRconsole V2
                      Bandwidth 400 Hz, AGC slow, IF 1.6, RF 20 dB
                      Decoder: YaND 6.4 #1
                      Antenna refurbished ALA1530
                      Receiver 2:
                      AR7030plus, bandwidth 2100 Hz, AGC slow,
                      Mode CW, pitch 1300 Hz, YaND 6.4 #2
                      Antenna pa0rdt-Mini-Whip, 5 m up the stem
                      of a magnolia tree
                      Computer: Intell E8200 CPU, 4 GB RAM
                      =============================================
                    • Roelof Bakker
                      Hello all, My apologies for the wrong posting! 73, Roelof Bakker
                      Message 10 of 15 , Apr 10, 2014
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                        Hello all,

                        My apologies for the wrong posting!

                        73,
                        Roelof Bakker
                      • Karel Honzík
                        Hello Roelof, thanks for your comment and advice. I am a bit disappointed that very few people responded to this issue, maybe they never came across it. It
                        Message 11 of 15 , Apr 10, 2014
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                          Hello Roelof,
                          thanks for your comment and advice. I am a bit disappointed that very few
                          people responded to this issue, maybe they never came across it. It seems
                          everyone is well protected but for me :-)

                          Karel


                          -----Původní zpráva-----
                          From: Roelof Bakker
                          Sent: Thursday, April 10, 2014 12:02 PM
                          To: perseus_SDR@yahoogroups.com
                          Subject: Re: [perseus_SDR] Strange behaviour of Perseus

                          Hello Karel,

                          There might have been static build up on the long wire.
                          You can use a bleed resistor of say 100.000 ohm between the longwire and
                          (radio) ground.
                          This will prevent voltage build up without effecting reception.

                          What happens inside the PERSEUS is difficult to say.
                          I believe that the input has a rf isolating transformer.

                          Best regards,
                          Roelof Bakker


                          ------------------------------------

                          Yahoo Groups Links
                        • Dave
                          Hi Karel, I did not reply because I did not have anything useful to add, because as you said, this has not happened to me as yet. I did read your request and
                          Message 12 of 15 , Apr 10, 2014
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                            Hi Karel,

                            I did not reply because I did not have anything useful to add, because as
                            you said, this has not happened to me as yet.

                            I did read your request and the replies in case it happened to me, but I
                            thought that replying that I had no idea what was wrong, nor how to cure the
                            problem, would not have helped you and would have meant that you had to read
                            a message that did not help your situation.

                            Dave (G0DJA)

                            ----- Original Message -----
                            From: "Karel Honzík" <
                            To: <perseus_SDR@yahoogroups.com>
                            Sent: Thursday, April 10, 2014 6:30 PM
                            Subject: Re: [perseus_SDR] Strange behaviour of Perseus


                            > Hello Roelof,
                            > thanks for your comment and advice. I am a bit disappointed that very few
                            > people responded to this issue, maybe they never came across it. It seems
                            > everyone is well protected but for me :-)
                            >
                            > Karel
                          • Wolfgang
                            Hello Karel, Did not answer too, because I never had this problem. But it really seems to as Roelof said. Strong winds cause static effects. I have mesured
                            Message 13 of 15 , Apr 11, 2014
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                              Hello Karel,

                              Did not answer too, because I never had this problem. But it really
                              seems to as Roelof said. Strong winds cause static effects. I have
                              mesured some 100 Volts at a long wire (app. 80 m long) and I did the
                              mistake to touch the wire. I can tell you it really has power, hi

                              When you connect the antenna to ground it goes down to 0 Volts and then
                              increases again depending to the wind.

                              So it explains your problem quite well.

                              You connct to the long wire and voltage on the wire goes to 0 Volts (or
                              a bit above) when voltage increases you get exactly that effect.

                              Do as Roelof suggested: Add a 100kOhm resistor to ground and things will
                              be ok, as there is no real high current to be handled.
                              You could also add a neon lamp (as used inside the electric
                              screwdrivers) to discharge the antenna at around 60 Volts (where the
                              neon lamp will fire).

                              73 Wolfgang, dl7nb
                            • Roelof Bakker
                              Hello Wolfgang, ... This will also make a nice thunderstorm detector. I used to have a double spark gap of about 2 mm over the open feeders of my HF doublet.
                              Message 14 of 15 , Apr 11, 2014
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                                Hello Wolfgang,

                                > You could also add a neon lamp (as used inside the electric
                                > screwdrivers) to discharge the antenna at around 60 Volts (where the
                                > neon lamp will fire).

                                This will also make a nice thunderstorm detector.
                                I used to have a double spark gap of about 2 mm over the open feeders of
                                my HF doublet.
                                Often a "tick tick tick" could be observed on my receiver when a storm was
                                nowhere to be seen or heard.
                                With an approaching storm the flash overs could be detected by ear!

                                73,
                                Roelof, PAoRDT


                                --
                                Gemaakt met Opera's e-mailprogramma: http://www.opera.com/mail/
                              • Jurgen Bartels
                                ... AFAIR Karel uses an impedance transformer. If that s the case he does not have the static charge problem. ... I still vividly remember this event: In
                                Message 15 of 15 , Apr 11, 2014
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                                  > Did not answer too, because I never had this problem. But it really
                                  > seems to as Roelof said. Strong winds cause static effects. I have
                                  > mesured some 100 Volts at a long wire (app. 80 m long) and I did the
                                  > mistake to touch the wire. I can tell you it really has power, hi

                                  AFAIR Karel uses an impedance transformer. If that's the case he does not have
                                  the static charge problem.

                                  ----
                                  I still vividly remember this event:
                                  In November 1981 at work I used a 10m wire on a roof connected to a Rhode &
                                  Schwartz Rx. Suddenly its input relays attenuator started to switch wildly. We
                                  were clueless about what was going on. So a coworker pulled off the antenna
                                  cable and then yelled "ouch" and threw the cable away. We then held the cable
                                  against the waterpipe and saw 5mm sparks!!
                                  It stopped after 5 minutes when the cloud outside had moved on. There was no
                                  T-storm at all. That tells you what voltages can develop even on a dreadful
                                  grey & cold November afternoon.






                                  Jurgen Bartels Suellwarden, N. Germany
                                  Ant. hor: 29-45MHz 7-el, 45-87MHz 11-el, FM 15.11, Band-3:13-el, UHF:48-el
                                  TV: Winradio G305 / Fly2000 + video noise filter & variable IF BW
                                  FM: Downconverter + Perseus + Speclab as WFM demod.
                                  MW: 30 x 4m EWE 320° with JB-terminator, Winradio & Perseus
                                  http://zeiterfassung.3sdesign.de/station_list.htm
                                  http://dx.3sdesign.de/tv_offset_list.htm
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