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Re: [Sangean803] DX440 Front End FET

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  • John Birkett
    Have you been using an external antennae ? These sets are prone to static build up when using external antennaes, there is something on here somwhere about a
    Message 1 of 7 , Aug 1, 2007
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      Have you been using an external antennae ?

      These sets are prone to static build up when using external antennaes, there is something on here somwhere about a bleed resistor or summat, that is mounted in the exernal antennae to earth path

      John in the N.W. UK



      > I'm the new guy - my '440 ate it's front-end FET,
      > but I have no schematic nor board layout. Could
      > somebody be so kind as to tell me WHERE the FET is
      > on the board, and how oriented, so that I can change
      > it out? I also need the value of R-06, as whatever
      > took out the FET, also ate the resistor.
      >
      > Thanks, as I use the heck out of this little
      > receiver for shop work. NOTE: Got a manual you'd
      > like to sell or copy for me? I'll pay for GOOD
      > copies.
      >
      > Tom
      >
      > [Non-text portions of this message have been
      > removed]
      >
      >

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    • Thomas C. Dailey - Dailey Services, LLC
      Oh, of course I used an external antenna... usually unhooked it when storm activity approached, but this apparently came on a calm, quiet day. Here in Denver,
      Message 2 of 7 , Aug 1, 2007
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        Oh, of course I used an external antenna... usually unhooked it when storm activity approached, but this apparently came on a calm, quiet day. Here in Denver, we have (usually) very low humidity, so static builds easily. I use an Alpha Delta on the ham station, but alas... my trusty '440 took it right on the chin. The resistor I inquired about (R-6), provides a nice ground-return for the excess voltage that came in, so it's explained too. Now, I just have to get an FET and stick it in, as well as the 1/8w resistor. I use this receiver in my shop for "monitoring". I work on a lot of tube-type gear, and it makes a great way to sample local oscillators and such.

        Tom

        [Non-text portions of this message have been removed]
      • John Birkett
        Ah well that explains that. I wonder if anyone with more knowlege than I ( or knows where it is written on this group ) could offer a simple fix for
        Message 3 of 7 , Aug 1, 2007
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          Ah well that explains that.

          I wonder if anyone with more knowlege than I ( or knows where it is written on this group ) could offer a simple fix for preventing static build up in simple external anntenas ?

          @ Thomas - A tube engineer - a rare breed indeed these days and much in demand I would bet !

          Shame yu could not use a tube reciever for your purpose - they don't suffer from a few KV of static do they !!!!

          John in the N.W. UK

          "Thomas C. Dailey - Dailey Services, LLC" <daileyservices@...> wrote: Oh, of course I used an external antenna... usually unhooked it when storm activity approached, but this apparently came on a calm, quiet day. Here in Denver, we have (usually) very low humidity, so static builds easily. I use an Alpha Delta on the ham station, but alas... my trusty '440 took it right on the chin. The resistor I inquired about (R-6), provides a nice ground-return for the excess voltage that came in, so it's explained too. Now, I just have to get an FET and stick it in, as well as the 1/8w resistor. I use this receiver in my shop for "monitoring". I work on a lot of tube-type gear, and it makes a great way to sample local oscillators and such.

          Tom

          [Non-text portions of this message have been removed]






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        • Jerry
          To protect the FET I use 2 1N914 Diodes Back to back. There is no loose when receiving.. That may occur with a resistor.. It conducts at I think 60mV So
          Message 4 of 7 , Aug 1, 2007
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            To protect the FET I use 2 1N914 Diodes Back to back. There is no loose when
            receiving.. That may occur with a resistor.. It conducts at I think 60mV So
            anything higher is sent to gnd.. I use my radio in a HIGH RF environment. I
            have the following radios working here at home 24/7 in a Packet Radio and
            other digital modes..



            4 HF rigs at 100 Watts each..

            3 VHF at 65 to 100 Watts

            2 UHF at 100 Watts

            % PC's and lots of other electronics.. And have not had any problems since
            replacing mine and adding the Diodes.



            73 Jerry N9LYA





            _____

            From: Sangean803@yahoogroups.com [mailto:Sangean803@yahoogroups.com] On
            Behalf Of John Birkett
            Sent: Wednesday, August 01, 2007 5:00 AM
            To: Sangean803@yahoogroups.com
            Subject: Re: [Sangean803] DX440 Front End FET



            Have you been using an external antennae ?

            These sets are prone to static build up when using external antennaes, there
            is something on here somwhere about a bleed resistor or summat, that is
            mounted in the exernal antennae to earth path

            John in the N.W. UK

            > I'm the new guy - my '440 ate it's front-end FET,
            > but I have no schematic nor board layout. Could
            > somebody be so kind as to tell me WHERE the FET is
            > on the board, and how oriented, so that I can change
            > it out? I also need the value of R-06, as whatever
            > took out the FET, also ate the resistor.
            >
            > Thanks, as I use the heck out of this little
            > receiver for shop work. NOTE: Got a manual you'd
            > like to sell or copy for me? I'll pay for GOOD
            > copies.
            >
            > Tom
            >
            > [Non-text portions of this message have been
            > removed]
            >
            >

            __________________________________________________________
            Luggage? GPS? Comic books?
            Check out fitting gifts for grads at Yahoo! Search
            http://search.
            <http://search.yahoo.com/search?fr=oni_on_mail&p=graduation+gifts&cs=bz>
            yahoo.com/search?fr=oni_on_mail&p=graduation+gifts&cs=bz




            ---------------------------------
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            [Non-text portions of this message have been removed]





            [Non-text portions of this message have been removed]
          • Thomas C. Dailey - Dailey Services, LLC
            Thanks to Jerry for the tip on the 1N914 diodes... never thought of using those, but yes, they re good switches. My 440 is out in the shop, where the other
            Message 5 of 7 , Aug 2, 2007
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              Thanks to Jerry for the tip on the 1N914 diodes... never thought of using those, but yes, they're good switches. My '440 is out in the shop, where the "other" rig is, a restored SWAN 350 using a long wire, through a homebrewed coupler, so the RF field can get high, but whenever I used the old '350, I'd disconnect the 440. I got the 440 from a dear friend who became a Silent Key some time ago, and was amazed at it's performance... he used it for a Novice receiver, and I can say, that it sure would have performed better than the BC-348 I got to use, all those years ago in 1962.

              Tom

              [Non-text portions of this message have been removed]
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