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HEEELLLLLLLLLLLLLLLPPPPP!!!!!!!!!!!!!!!!!!!!!! and Oh ,yes Hello!

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  • rifleman336
    Hello, everyone. My name is Alex Kaminski, I am a military monitoring hobbist. I am licensed amature radio operator(N8UCN). I ve a no code tech for the last 13
    Message 1 of 6 , Dec 3, 2005
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      Hello, everyone. My name is Alex Kaminski, I am a military

      monitoring hobbist. I am licensed amature radio operator(N8UCN). I've

      a no code tech for the last 13 years.

      I was wondering if anyone could help me. I picked up a Dx-394 at

      Hamvention two years ago. It had a both a users and service manuals

      included with it.


      The problem is is the audio in sigle sideband is very distorted.

      When my father ( an Avionics tech for an airlines) traced the problem

      down to the Ceramic resonators both upper and lower sideband sibes

      were bad.


      I tried calling Radio Shack and Radio Shack Iternational with no

      luck. Then I called GRE in California, they didn't have any staff that

      was very fluant in english and they more or less refused to help. Now

      I know that the radio is still being sold in Europe. One british radio

      outlet still advertises it in SWM magazine. Unfortunatly, they don't

      have a web site in which to contact them. I then tried to find some

      ceramic resonators from electronic componates suppliers and as usual I

      struck out.

      So does anyone know where I can find replacment parts, or any way

      that GRE in Japan can be contacted for parts? Is there a sevicing

      facility that would service it?


      I think it would be a tragdy if this unit can't be fix not

      alone modified like I would like to do.



      Thank you,

      Alex N8UCN
    • Tom Holden
      ... Hi Alex, Before you write off the SSB filter as being faulty, it would be wise to check the alignment of the radio. Please describe the distortion.
      Message 2 of 6 , Dec 3, 2005
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        > ----- Original Message -----
        > From: "rifleman336" <rifleman336@...>
        > The problem is is the audio in sigle sideband is very distorted.
        >
        > When my father ( an Avionics tech for an airlines) traced the problem
        >
        > down to the Ceramic resonators both upper and lower sideband sibes
        >
        > were bad.

        Hi Alex,

        Before you write off the SSB filter as being faulty, it would be wise to
        check the alignment of the radio. Please describe the distortion.

        Replacement parts are hard to find. You could get a filter from Kiwa - its
        narrow AM filter for the DX-394 is pretty close to the stock SSB filter.

        The stock SSB filter is twice as wide as we would like for SSB; if it is
        replaced by a sharper filter, other mods are required to the BFO to change
        its frequencies for SSB demod to work.

        73, Tom
      • rifleman336
        ... distorted. ... problem ... sibes ... wise to ... Kiwa - its ... filter. ... it is ... to change ... Hi Tom, My father being the experianced tech he is
        Message 3 of 6 , Dec 4, 2005
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          --- In RADIOSHACKDX394@yahoogroups.com, "Tom Holden"
          <holden_family@s...> wrote:
          >
          > > ----- Original Message -----
          > > From: "rifleman336" <rifleman336@y...>
          > > The problem is is the audio in sigle sideband is very
          distorted.
          > >
          > > When my father ( an Avionics tech for an airlines) traced the
          problem
          > >
          > > down to the Ceramic resonators both upper and lower sideband
          sibes
          > >
          > > were bad.
          >
          > Hi Alex,
          >
          > Before you write off the SSB filter as being faulty, it would be
          wise to
          > check the alignment of the radio. Please describe the distortion.
          >
          > Replacement parts are hard to find. You could get a filter from
          Kiwa - its
          > narrow AM filter for the DX-394 is pretty close to the stock SSB
          filter.
          >
          > The stock SSB filter is twice as wide as we would like for SSB; if
          it is
          > replaced by a sharper filter, other mods are required to the BFO
          to change
          > its frequencies for SSB demod to work.
          >
          > 73, Tom
          >



          Hi Tom,


          My father being the experianced tech he is checked the
          alignement first thing, and it was perfectly fine. The distortion
          sounded like a blown speaker. In fact, I replaced it(the speaker)
          first thing. Now in AM mode it sounds great, flip to SSB especially
          upper sideband (Where all the action is at)was unintellagable. Lower
          side was better but, not by much. Now you refer to a filter/BFO mod.
          What mod are you refering to and where does one get the KIWA
          filters.

          Again thank you for your help,
          Alex
        • mikemaghakian
          I don t think he means the IF filter, I think he is talking about the BFO crystal s. the two blue items near the front of the radio. by the way, alex, if you
          Message 4 of 6 , Dec 5, 2005
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            I don't think he means the IF filter, I think he is talking about the
            BFO crystal's. the two blue items near the front of the radio.

            by the way, alex, if you want to sell it let me know. I don't care
            about SSB on the 394. my public stance is that the 394 is a poor
            choice for SSB work.





            --- In RADIOSHACKDX394@yahoogroups.com, "Tom Holden"
            <holden_family@s...> wrote:
            >
            > > ----- Original Message -----
            > > From: "rifleman336" <rifleman336@y...>
            > > The problem is is the audio in sigle sideband is very
            distorted.
            > >
            > > When my father ( an Avionics tech for an airlines) traced the
            problem
            > >
            > > down to the Ceramic resonators both upper and lower sideband sibes
            > >
            > > were bad.
            >
            > Hi Alex,
            >
            > Before you write off the SSB filter as being faulty, it would be
            wise to
            > check the alignment of the radio. Please describe the distortion.
            >
            > Replacement parts are hard to find. You could get a filter from
            Kiwa - its
            > narrow AM filter for the DX-394 is pretty close to the stock SSB
            filter.
            >
            > The stock SSB filter is twice as wide as we would like for SSB; if
            it is
            > replaced by a sharper filter, other mods are required to the BFO to
            change
            > its frequencies for SSB demod to work.
            >
            > 73, Tom
            >
          • Paul Hurm
            I have listed my DX-394 on ebay as auction number 5838921520 for anyone who may be interested. Thanks. Paul Hurm N8OT
            Message 5 of 6 , Dec 5, 2005
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              I have listed my DX-394 on ebay as auction number 5838921520 for anyone who
              may be interested.

              Thanks.

              Paul Hurm
              N8OT
            • Tom Holden
              ... Hi Alex, Below 10 MHz, most ham SSB is LSB. That you find LSB and USB to sound pretty much the same and like a blown speaker may suggest some problem with
              Message 6 of 6 , Dec 7, 2005
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                >     My father being the experianced tech he is checked the
                > alignement first thing, and it was
                perfectly fine. The distortion
                > sounded like a blown speaker. In fact, I
                replaced it(the speaker)
                > first thing. Now in AM mode it sounds great,
                flip to SSB especially
                > upper sideband (Where all the action is at)was
                unintellagable. Lower
                > side was better but, not by much. Now you refer
                to a filter/BFO mod.
                > What mod are you refering to and where does one
                get the KIWA
                > filters.
                Hi Alex,
                 
                Below 10 MHz, most ham SSB is LSB.
                 
                That you find LSB and USB to sound pretty much the same and like a blown speaker may suggest some problem with the product detector, noise blanker or AGC. Does it clear up if you switch in the RF attenuator or back off on the RF Gain?
                 
                By blown speaker-like, do you mean it is like the cone is flopping around really badly with lots of bass or that it is thin, tinny and weak compared to AM? The former was what I had in mind in the previous paragraph. The latter relates to the following paragraph.
                 
                The critical alignment for SSB quality is that the BFO frequencies should be very close to 451.5 kHz (LSB) and 458.5 kHz (USB), on the sides of the filter skirts. Too far below 451.5 or above 458.5 will cause the thin sound. If the error is too much the other way, it will sound very full to the point of being woofy and adjacent interference will also be woofy.
                 
                The alignment of the 1st and 2nd local oscillators sets the accuracy of tuning and uniformity of fine tuning steps - the latter is also critical to being able to tune in all SSB frequencies - gross misalignment can result in some fine tuning steps very much larger than 100 Hz so it is not possible to tune close enough. If you want to better understand how the DX-394 actually tunes, have a look at my rather dense article:

                OSC/IF: PRINCIPLES OF TUNING
                (Holden)
                03.01.18

                Understand the Principles of DX-394 Frequency Tuning.

                Description, block diagram, explanation, graphs, ideas for mods for improved fine tuning linearity.

                RADIOSHACKDX394
                www.mods.dk

                msg# 318 2368 2422ff

                 
                Then explore the list of mods sorted under OSC in the Master Index of Mods for tips on aligning.
                 
                If your SSB/CW modes filter is really duff, replacing it with the one normally sold by Kiwa as an improvement on the AM filter should work:
                 

                IF: KIWA AM FILTER
                (Kiwa Electronics)
                03.01.18

                Better selectivity in AM mode

                Unsolder 4-pin AM filter and replace it with US$18 Kiwa Electronics DX-394 filter kit.

                http://www.kiwa.com/rsdx.html

                 
                You'll also find many more mods and tips about the IF filters in the Master Index. If you go the route of a really narrow filter for SSB, you will also find this useful:
                 

                IF: NARROWER SSB/CW FILTER
                (Wayne)
                03.01.21

                Better selectivity in SSB/CW modes but introduces error of up to 3 kHz in frequency displayed.

                Remove SSB/CW filter, replace with sharper filter (may need a daughter pcb to adapt to DX-394); remove BFO ceramic resonators, replace with modified 455 kHz transformers and retune; provide regulated voltage to BFO.

                msg# 687

                Also see 2465 for a discussion of the effects of poor selectivity and the remedies

                 
                73,
                 
                Tom VE3MEO
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