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Saltwater Dummy Load

Discussion in 'Home Brew' started by HomerBB, Oct 30, 2010.

  1. HomerBB

    HomerBB Sr. Member

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    I know it's been done by a lot of people, but this is the first i decided to make. Pint sized, it used only 1/8 teaspoon of salt to bring it down from freshwater 3+ SWR to <1.1:1
    The needle barely moved on all frequencies. The photos show the dummy load, SWR meter, and the radio at the three frequencies of 25.605, 27.185, and 28.755.



    [​IMG] [​IMG] [​IMG]
     

  2. radiodawg259

    radiodawg259 Member

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    HomerBB can you send all the info. on building one of them,looks cool.
     
  3. tecnicoloco

    tecnicoloco Tweaknician in Training

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    Hello just follow this link

    Salt Water Dummy Load


    Have fun it works :D
     
  4. HomerBB

    HomerBB Sr. Member

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    Yep. That's the link I went to.
     
  5. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    So, what happens if you run high power into one? I mean after the water starts to boil or the water breaks down into components of hydrogen,oxygen,sodium, and chlorine, which it will do when an electrical current is passed through a solution? Do the electrodes become tarnished and if so does that affect anything?

    I don't know. I don't think I would want to trust my good HF rig or an amplifier to a bottle of briny water. I'll stick to my pile of carborundum in a stew pot of silicone load oil. :D

    Inside:

    [​IMG]


    Outside:

    [​IMG]
     
  6. HomerBB

    HomerBB Sr. Member

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    Captain KW, I think you pose some decent questions, answers to which I don't have. Seeing if I had a handle like yours it would be Buck Private Microwatt, I don't think I'll ever need to worry over it. With a maximum dead key through my little amp of 90 watts, I am not anticipating too much trouble. I key 2 watts from my radio.

    I held the 90 watts dead key for 3 minutes with barely any heat at the top of the water level, still cold elsewhere. I was unwilling to hold longer dead key for any longer seeing I could think of no good reason as the 3 minutes is well within any purpose I'd have for the pint-sized dummy load. The amp is a low drive 250 watt unit so I won't turn up the radio to raise the dead key.

    By the way, the SWR was a mere 1.3:1 with the 90w dead key. A tad more salt and I might get that down, too.

    If I make you one will you tell us how it goes? ;)

    BTW, that's a really nice dummy load you're showing us. Some guys have all the good stuff . . .
     
  7. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    It's a sad state of affairs when your tubes don't have handles but your dummy load does. :laugh:
     
  8. hookedon6

    hookedon6 W9WDX Amateur Radio Club Member

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    a TOOB with handles, HEY, i've got one of those too;);)

    BTW: i used to "saltbox" electrical generators for load tests, and yes the water WILL bubble and boil if you put enough megawatts through it
     
  9. HomerBB

    HomerBB Sr. Member

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    Okay, After Cap'n KW's photos these are dinky, but they are pretty self explanatory:

    [​IMG] [​IMG] [​IMG]
     
  10. Radio Tech

    Radio Tech Radio Operator

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    The salt water dummy load really works nice. Just be careful with it. They can be worse than a grenade going off.
     
  11. HomerBB

    HomerBB Sr. Member

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    I will use it with care.
     
  12. Beetle

    Beetle Sr. Member

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    Be extremely careful about adding more salt with the aim of lowering the indicated SWR. City water (in some cities) doesn't need any salt at all to be nicely conductive. Southern Nevada has some of the worst water in the country for drinking, but it's usable for projects like this one. I didn't see if you measured the DC resistance across the SO-239, but it should be pretty close to 50 ohms, and especially in a small container like a pint jar, it doesn't take much salt at all to get the resistance down. In some areas as I mentioned above, you might actually have to add distilled water to get the conductivity level where you want it!
     
  13. linearone

    linearone King of NY

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    if anyone wants to donate a big one for testing let me know. I can generate quite a bit of rf and would love to see a dummy load explode!
     

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