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Changing the antenna input impedance DX-440

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  • Lawrence
    Thanks Bob and Andy for your last posts. (Zener diode & the DOS inductance calc). I typed a reply that day, but apparently Yahoo had a seizure & it never went
    Message 1 of 33 , Jan 3, 2010
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      Thanks Bob and Andy for your last posts. (Zener diode & the DOS inductance calc). I typed a reply that day, but apparently Yahoo had a seizure & it never went through. But thanks, both of those will be useful.

      For now I've decided to order more Flex-weave wire, to add many more turns to my large longwave receiving loop. I sort of feel like a fool for 'downgrading' to a single-turn like I had. But, would you believe that, the other night, I got a 36 mile-per-watt beacon catch on that, on the DX-440? A 25 watt beacon 900 mi from here.

      I have another question that you may be able to help with:

      The DX-440's antenna input jack is 75-ohm I believe. Or 50-ohm; either way its low impedance. IF I were to simply bypass that jack internally, would that alone give my a Hi-Z connection?

      Thanks.


      Larry Lanberg

      Richmond VA
    • Lawrence D Lanberg/FS/VCU
      It s good that you re stirring-up hornets, Bob. I experiment a lot on my own, but you & Andy give some really valuable insight. I appreciate it. Btw... I
      Message 33 of 33 , Jan 11, 2010
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        It's good that you're stirring-up hornets, Bob. I experiment a lot on my
        own, but you & Andy give some really valuable insight. I appreciate it.
        Btw...

        I finally got my 'extra' wire, increasing the windings on my large loop.
        (See pictures section of this group for view of the loop). From 1 winding
        to, now, 4 winds. This gives a calculated inductance of 82.8 uH. Well, my
        HF utility reception is fantastic! RAF in England no problem. Also I can
        better copy 60 WWVB and 100 LORAN. - Keep in mind I have an LF upconverter
        for these low frequencies - So the extra windings really boosted 10-100
        kHz and 530-20000 kHz. BUT the strange thing is, my 'middle' reception has
        taken a dive. That is, I'm getting worse reception from 100-530 kHz. Which
        is my area of interest.

        I THINK I need to get lower-value caps for 100-530 kHz, because my
        inductance has now increased 8x. But still, if that was the case, I don't
        understand why the really low stuff (60 & 100 kHz) has improved.



        Larry Lanberg



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