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Re: [GenesisRadio] Re: Questions related to G11 and adjustment

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  • Bruce KF1Z
    JMP1E is the ground connection for audio on the FM line out connector Removing that jumper can eliminate any ground loop between the audio cables. ( line-in
    Message 1 of 7 , Feb 4, 2013
      JMP1E is the ground connection for audio on the "FM line out connector" 
       
      Removing that jumper can eliminate any ground loop between the audio cables. ( line-in and line-out to soundcard.)
       
      However, there can still be a ground loop between USB cable and audio ground.
       
      in this case, a USB isolator is recommended.
       
      ( it is possible to remove 2 components from USB input to do this... but I have NOT tried it, and it could cause loos of connection, or instability)
       
      Bruce
      kf1z
       
      BTW, some USB soundcards such as the E-MU line, have ground lift switches on the bottom of the case
       
       
      From: Angel
      Sent: Monday, February 04, 2013 1:51 PM
      Subject: [GenesisRadio] Re: Questions related to G11 and adjustment
       
       

      Thank you Tasa.

      With regards to: ""Prevent unwanted ground loops! QSD (quadrature
      sampling detectors) SDR is 90% audio technique it is always good that we
      have ground star configuration instead several loops(audio in /out ,USB
      cables to sound card and PC). In G59 and G11 you can lift ground
      connection to prevent this problem type""

      Apologies if this is very basic or has been answered before.
      In practical terms, how do you lift ground connection on G11?

      73
      Angel
      M0HDF

      --- In mailto:GenesisRadio%40yahoogroups.com, Sinisa Tasic wrote:

      >
      > Hello group,
      >
      > I shall try to
      clarify several topics in last messages at Genesis
      group.
      >
      > 1.
      Hump in center of spectrum is normal thing. The source can be
      hardware
      > and software type. This problem exist in solution such as
      QSD Genesis
      > design but also in receivers with high speed AD converters
      such as
      > Perseus.... The big difference is that Perseus is not using
      spectrum
      close
      > to the 0Hz in QSD designs this part is always in the
      middle! That it
      is not
      > strange can you find me any spectrum analyzer
      which is without even a
      small
      > hump around 0 HZ?
      > It is
      important for practical use that this hump is small as possible.
      What
      >
      can we do to decrease hump?
      > - Prevent unwanted ground loops! QSD
      (quadrature sampling detectors)
      SDR is
      > 90% audio technique it is
      always good that we have ground star
      > configuration instead several
      loops(audio in /out ,USB cables to sound
      card
      > and PC). In G59 and G11
      you can lift ground connection to prevent this
      > problem type . Also some
      sound card like EMU202, EMU204 have switches
      for
      > lifting ground
      connection at one side. To finding optimum solution
      with
      > max
      rejection noises and interferences it is necessary make
      experiments
      >
      there is no universal receipt!!
      > - Use very good audio cables with
      perfect ground shield. Most of
      > commercial available cables have very
      poor quality and hot wire
      inside
      > cable is collecting unwanted noises,
      signals from surround and PC
      (USB
      > HUB, AC switches...). Very good
      quality audio cables(excellent with
      double
      > shied) with separate
      cables for L/R channels are good solution . To
      stop
      > collecting
      unwanted signals with cables shield add some ferrite tubes
      ,
      > cores
      and wind cable around cores or pass through it to prevent so
      call
      >
      common mode current ! You can use some ferrite tubes or cores from
      old
      > CRT display (cable for connection for PC was passing through
      it). It
      is
      > good practice to put all cables through the ferrite
      tubes-cores !
      Good
      > solution for reducing unwanted noise and
      interferences is small
      diameter
      > cables such as RG174 or some smaller
      one. It will enable very good
      > rejection unwanted signals but practically
      is not easy way to put 2
      cables
      > RG174 in one 3,5 male audio jack! It
      is good practice that all cables
      are
      > not longer than it is necessary
      !! Shorter will always give good
      results.
      > The RG174 is 50OHMs cable
      it is not good idea to have very long cable
      with
      > RG174 it is possible
      in some case unwanted oscillation audio or RF
      from
      > driving stage in
      SDR transceiver or audio card!
      > -Galvanic separation with audio
      transformer. Good audio transformers
      in
      > such wide range of almost
      0-96KHZ is not easy find and they are
      expensive.
      > One friend of mine
      use this proposal for galvanic isolation from
      article
      > down and this
      proposal is giving really very good results in his and
      my
      > tests! The
      author of this article is IW3AUT
      >
      href="http://www.rfsystem.it/shop/download/Audio_isolator.pdf">http://www.rfsystem.it/shop/download/Audio_isolator.pdf I like thank
      you
      > to my friend Lada OK1UNL for this link.
      > It
      is possible to try every solution separately or combine severals.
      I
      >
      am giving guarantee that if you use some of proposed technique you
      will
      > obtain improvement in some cases it will very dramatic
      improvement.
      There
      > is no universal receipt for this type of problems
      even if you are
      using
      > brand name PC and sound cards!
      > 2. The
      Genesis and I am using very effective way to carrier rejection
      in
      >
      transmit section. This type of solution can give carrier rejection
      even to
      > 70-80dB. It is necessary to be dome slowly in several iteration as
      it
      is
      > explained in all assembling mauals. Good results is around
      50-55dB
      you can
      > find results in .doc which I uploaded some times ago
      ! Here is
      important
      > that you have reference point (max output power )
      and than count dB to
      this
      > level. All HF receivers are very sensitive
      and they can receive very
      weak
      > signals typically for G11 from -114 to
      -116dBm to -7dBm basic setup
      > without additional RF and audio gain what
      is more than 107dB! Because
      of
      > that it not strange that you can heard
      carrier !!! IT is normal
      situatio
      > that if we increase frequency that
      balance for carrier rejection is
      not
      > good. It is not usual situation
      as it is described in message that
      it is
      > worse at lower
      frequencies.
      > 3. Unwanted image (opposite side band in classic design) it
      is
      possible
      > reject with hardware adjustment from 45-55dB or more.
      Please see my
      > results for G11 hardware adjustment measurements! With
      software
      adjustment
      > it is possible image reject to 60-80 dB! For both
      carrier and image
      > rejection please check in transmitter GSDR setup use
      DC block !
      > 4. It is not clear such kind of echo you are hearing ? As I
      explained
      many
      > times before to check full hardware functionality of
      G11 and G59 you
      do not
      > need PC after you setup frequency (of course I
      am expecting that Si570
      LO
      > is working what is situation i almost
      100%)! If you connect antenna
      you
      > will hear some signals from band
      sometime weak sometimes with low
      sometimes
      > with very high pitch
      frequency. The phones are connected to RX output
      > connector to sound card
      line in instead cable If you can hear this
      from
      > GSDR software that is
      problem related for PC and GSDR setup!
      > 5. If you plug in MIC in MIC G11
      jack or G59 mic jack and phones to
      line in
      > jack instead cable you
      will hear yourself as you start talking. The
      audio
      > quality need to be
      high. You can make choice with jumper between two
      mic
      > audio gain
      position. There is no delay ! But if you are listening
      signal
      > with
      phones which is goiung from souind card out to G11 or G50 line
      out
      >
      you will hav edelay and this will confuse you because it is like a
      echo !
      > If you use this test with external speaker instead phones you
      will
      have
      > microphonic effect what is normal situation because here is
      not VOX
      and
      > untivox control! Use minimum mic gain and all other
      adjustment make in
      GSDR
      > setup !
      > 6. Hardware high SWR
      protection . GPA10 and G11 output transistor
      RD16HHF1
      > are very robust
      . They are used in the majority commercial transceiver
      as
      > driver
      stage nowadays. First adjustment is to move control voltage for
      > control
      to +3.5V. Adjust direct and reflected power reading and than
      slowly
      >
      decrease this voltage to +2.2-+2.5 V.
      >
      > I hope that my explanation
      will help !
      > VY 73 GL in SDR homebrew Tasa
      YU1LM/QRP
      >

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