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SGC-237 relay unlatching every two seconds after tune

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  • stanza4u
    I ve used my SGC237 for a few years with a vertical loop 80ft. long of 14awg wire installed in my attic. It worked decent on 80-10. I recently removed the
    Message 1 of 3 , Apr 1, 2012
      I've used my SGC237 for a few years with a vertical loop 80ft. long of 14awg wire installed in my attic. It worked decent on 80-10.

      I recently removed the vertical loop to put a ~130ft. wire loop into my attic along the perimeter of 12awg wire to get more radiation resistance on 80 and 40 meters.

      Well, my SGC-237 won't tune the new loop on any band. It will tune for a few seconds, then a relay unlatches and the SWR skyrockets. A moment later the relay will latch again and sometimes the tuner retunes and sometimes it returns to the previous tune setting from memory.

      I can see the SWR get very low to 1.3:1 on 80m, for example. But then, every 2 seconds a relay unlatches and the SWR shoots up high enough to make the protection circuit in my radio (Flex-5000) throttle back the power. I am tuning with 10 watts.

      I removed the case and can see that none of the led lights come on when I apply 12v, so I think the diodes are fine. I added a mix-31 ferrite choke to the coax feed of the tuner and that did not help.

      The relays all look good with no discoloration. I think maybe my cpu is tripping the relay every two seconds or something strange. I will do the lightbulb test in the next day or two and post my results.

      Any ideas what could be wrong with my coupler?

      Paul KC2DLA
    • astro_maryland
      Hi Paul, There may be nothing wrong with the SGC autocoupler. It could be (IMHO) that by increasing the physical dimensions (size) of the loop and you are now
      Message 2 of 3 , Apr 2, 2012
        Hi Paul,

        There may be nothing wrong with the SGC autocoupler. It could be (IMHO) that by increasing the physical dimensions (size) of the loop and you are now in *close* proximity with materials that are significantly interacting with the antenna wire (that's why it's occuring on all bands). These could be, but are not limited to air conditioning duct work, standard household wiring (including security systems & safety [smoke detectors and the like]), metal window frames, metal plumbing fixtures (gas, water, waste [may be not so common]) cable TV, satellite wiring or telephone, and metal downspouts and gutter systems.

        I know that you probably invested lots of work in the new loop. As a test, remove it and replace it with the original working vertical loop.

        Let us know what happened. Others may have 'easier' solutions.

        GL, 73, Rich, K3VAT


        --- In Smartuners@yahoogroups.com, "stanza4u" <pkrzewin@...> wrote:
        >
        > I've used my SGC237 for a few years with a vertical loop 80ft. long of 14awg wire installed in my attic. It worked decent on 80-10.
        >
        > I recently removed the vertical loop to put a ~130ft. wire loop into my attic along the perimeter of 12awg wire to get more radiation resistance on 80 and 40 meters.
        >
        > Well, my SGC-237 won't tune the new loop on any band. It will tune for a few seconds, then a relay unlatches and the SWR skyrockets. A moment later the relay will latch again and sometimes the tuner retunes and sometimes it returns to the previous tune setting from memory.
        >
        > I can see the SWR get very low to 1.3:1 on 80m, for example. But then, every 2 seconds a relay unlatches and the SWR shoots up high enough to make the protection circuit in my radio (Flex-5000) throttle back the power. I am tuning with 10 watts.
        >
        > I removed the case and can see that none of the led lights come on when I apply 12v, so I think the diodes are fine. I added a mix-31 ferrite choke to the coax feed of the tuner and that did not help.
        >
        > The relays all look good with no discoloration. I think maybe my cpu is tripping the relay every two seconds or something strange. I will do the lightbulb test in the next day or two and post my results.
        >
        > Any ideas what could be wrong with my coupler?
        >
        > Paul KC2DLA
        >
      • stanza4u
        Rich, Thank you for your thoughtful reply. I think you re right about the new loop coupling with metallic conductors in the attic. The cable chase for my
        Message 3 of 3 , Apr 2, 2012
          Rich,

          Thank you for your thoughtful reply. I think you're right about the new loop coupling with metallic conductors in the attic. The cable chase for my feedline comes up very close to an HVAC unit, so guess where my feedpoint is? It's very close to that HVAC unit. The smaller loop had the feedpoint further away.

          I think I will move the feedpoint away from that thing first, only because it is very easy. I will be able to tell if the coupler works any differently from the current location. It could get worse or maybe (I hope) better.

          If it still behaves the same then I will alter the loop size and location away from the side of the attic with the heater.

          By the way, my SGC-237 more or less passed the light bulb test, although it kept retuning on 80m and had trouble getting below 2:1 every time but the first try.

          Hey, thanks again!

          73,

          Paul KC2DLA

          --- In Smartuners@yahoogroups.com, "astro_maryland" <astro_maryland@...> wrote:
          >
          >
          >
          >
          >
          >
          > Hi Paul,
          >
          > There may be nothing wrong with the SGC autocoupler. It could be (IMHO) that by increasing the physical dimensions (size) of the loop and you are now in *close* proximity with materials that are significantly interacting with the antenna wire (that's why it's occuring on all bands). These could be, but are not limited to air conditioning duct work, standard household wiring (including security systems & safety [smoke detectors and the like]), metal window frames, metal plumbing fixtures (gas, water, waste [may be not so common]) cable TV, satellite wiring or telephone, and metal downspouts and gutter systems.
          >
          > I know that you probably invested lots of work in the new loop. As a test, remove it and replace it with the original working vertical loop.
          >
          > Let us know what happened. Others may have 'easier' solutions.
          >
          > GL, 73, Rich, K3VAT
          >
          >
          > --- In Smartuners@yahoogroups.com, "stanza4u" <pkrzewin@> wrote:
          > >
          > > I've used my SGC237 for a few years with a vertical loop 80ft. long of 14awg wire installed in my attic. It worked decent on 80-10.
          > >
          > > I recently removed the vertical loop to put a ~130ft. wire loop into my attic along the perimeter of 12awg wire to get more radiation resistance on 80 and 40 meters.
          > >
          > > Well, my SGC-237 won't tune the new loop on any band. It will tune for a few seconds, then a relay unlatches and the SWR skyrockets. A moment later the relay will latch again and sometimes the tuner retunes and sometimes it returns to the previous tune setting from memory.
          > >
          > > I can see the SWR get very low to 1.3:1 on 80m, for example. But then, every 2 seconds a relay unlatches and the SWR shoots up high enough to make the protection circuit in my radio (Flex-5000) throttle back the power. I am tuning with 10 watts.
          > >
          > > I removed the case and can see that none of the led lights come on when I apply 12v, so I think the diodes are fine. I added a mix-31 ferrite choke to the coax feed of the tuner and that did not help.
          > >
          > > The relays all look good with no discoloration. I think maybe my cpu is tripping the relay every two seconds or something strange. I will do the lightbulb test in the next day or two and post my results.
          > >
          > > Any ideas what could be wrong with my coupler?
          > >
          > > Paul KC2DLA
          > >
          >
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