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564RE: [stationpro] The hum problem

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  • Jim Garland
    Apr 7, 2014
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      Hi Wayne,

      I’m puzzled by the relay in the Amp keying line to reduce hum. The StationPro already uses an optically isolated relay to key the amplifier, and I don't see how another relay would add any benefit unless the hum is coming in on the ground lead from the amplifier.


      Jim W8ZR


      From: stationpro@yahoogroups.com [mailto:stationpro@yahoogroups.com] On Behalf Of k4elo@...
      Sent: Monday, April 07, 2014 8:54 AM
      To: stationpro@yahoogroups.com
      Subject: [stationpro] The hum problem



      After many frustrating days, the problem has not been eliminated
      completely, but brought down to an acceptable level.

      Now with only the Kenwood pod connected, there is zero hum. With the
      Flex pod also connected, it is there when transmitting from either rig,
      but at a very low level.

      The goal was to reduce the number of ground connections from the SPII to
      the rigs to as few as possible.

      Steps taken:
      Power the SPII from an isolated power supply.
      Add an isolation relay in the tx relay line to the amp.
      Remove all ground connections at the pods except the mic cable shield.

      Hopefully this may help someone else if they have hum problems.


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