Static Bleeder

When you are in the middle of the desert, pretty much every solution to a mechanical or electrical problem is a hack. [Sgt.M] who was deployed in Iraq sought out the help of radio guru [H.P. Friedrichs] about a static problem he was having. When dust storms would blow in strange things would happen in camp. Humming and crackling could be heard and [Sgt. M] actually had an electrical arc from a lamp to his hand at a distance of about 2 feet.

[Friedrichs] helped him find the problem. Their antennae were acting as static electricity collectors in the dust. All that dust friction in the dry air constantly built up a charge. The solution was simple, discharge the electricity at the antenna when it isn’t in use. Several solutions are outlined on the page, so check them out.

31 thoughts on “Static Bleeder

  1. I’m pretty sure this isn’t a “hack”. It’s used by professional and ham radio operators quite a bit for this very reason. In fact, I’m looking at an old copy of the ARRL Handbookand and it has the plans for a static arrestor.

  2. I used to be a science tech at the south pole. We had the same problem with a really long antenna. No ground at the south pole as it’s on top of two miles of ice. Fried some equipment when an ice storm blew in. took a long time to figure out what was wrong. We really could have used a “hack” like this. Thanks

  3. DUX: Actually, Polyphaser makes a very nice DC Grounded protector, if you have a high impedance connection in parallel to your antenna feed, the radio will ignore the shunt to ground (or use a MOV). It’s easier to use a spark gap though, it works like when you touch a door knob ang get popped.

    The military guys can order polyphasers with an NSN, so this leads me to believe they just wanted to tinker.

  4. @Jim Foster:
    Pure water in its _liquid_ state is an insulator. Conductance comes from impurities. I would assume that the crystallization process of ice forces out these impurities or at least immobilizes them.

  5. You guys are collectively come to the right answer re: water conduction. It’s the mobility of charges on impurities in the water (think stuff like table salt, which breaks into Na+ and Cl- ions in solution) that make it conductive, and when the water freezes those charges can’t bridge the lattice, making it a decent insulator. Water itself is a craptacular conductor, and ice even worse.

    @Bjonnh: Presumably. I’m not an electrical engineer, but my understanding is that static electricity (via friction) is a relatively inefficient source of juice and you would be much better off planting fields of solar panels in those same deserts. What we should be doing is hooking caps up to people’s socks and make them shuffle everywhere in the winter; we’ll all generate our own power and maybe keep our cellphones charged!

    Also, I dig this post.

  6. Sure you could order it with by NSN, but then you get to wait for 6 months to (maybe) get something (oops, wrong part). This is why we made our own solutions in the sandbox. I love an elegant solution to a real life problem.

  7. @rd

    Yeah, you’re probably right as ice generally doesn’t have salt in it. I would have thought there would be at least some impurities left in it though. That being said – I can’t imagine that dirt is that great of a conductor.

  8. Dirt isn’t conducting in this scenario, it is insulating, sand contains glass and other minerals. What do billions of tiny sand particles moving through dry air with just a bit of glass and other minerals get you ? billions of tiny capacitors all looking to dump their voltage.

    Back when the only way to make a laser was a very high voltage source and we couldn’t get large capacitors cheap made them with a sheet of glass then a sheet of aluminum, sheet of glass, then sheet of aluminum, until we had enough layers. The scenario with the antenna is as if someone took one of our capacitors and shattered it into millions of pieces.

  9. @catzburg
    “Now, I’m no EE (yet) but if you ground an antennae it ceases to function as an antennae, and becomes a ground.”

    if you want to become EE study AC networks, they behave almost totally different from DC

  10. The radio equipment used by Sgt. M seems to be built by some french company.

    I didn’t expect the US army to get anything right, but why do they make it even harder by using french equipment?

  11. Re: Sparkgaps.
    Yes, spark gaps do shunt antenna systems to ground and are usually used on AM towers to guard against lightning strikes. Do note, however, that spark gaps must be exposed in the air to work and with a sandstorm you will may create a potential between the two halves that prevents them from shunting in the same manner as they do otherwise. Spark gaps also need to be ‘tuned’ as they are essentially two metal balls with a small gap between them.
    The solution given here is much more elegant and easier to ship around the world.

      1. I once used a “semi sealed” spark gap: two tungsten cylinders as electrodes in a steel tube with bakelite like end caps. One of them had a small hole for pressure equalization. But they were designed so that the discharge (up to 100kA during a lightning strike) increases the pressure what helps to extinguish the arc. The use was as lightning arrestors in the distribution cabinet of a building.

  12. I’m surprised the military hasn’t investigated this problem (static) as a source of power for recharging the batteries they use. (Of course I don’t know how much power they’d get, but some is better than none, right?)

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