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#42
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![]() Cecil Moore wrote: wrote: J. Mc Laughlin wrote: Moving dust particles can carry charge and become charged. The noise does follow the "pattern of the particle rate." I've never seen it do that. But I'll keep watching for it. In Arizona, the harder the wind blew on a clear day, the shorter the length of time between arcs on my coax connector. In a high wind, it sounded something like the rat-a-tat of a machine gun. Let's see if I can explain this in 200 words or less. :-) One popular supposition is what Reg indictated, that P-static is caused by charged droplets hitting the antenna. As each little drop hits the antenna, it makes a noise from the transfer of charges. I always thought that also until I started working on antenna systems on tall towers and buildings. Trying to make them not "noise up" when the weather was bad turned out to be impossible when the antenna was near the top of a structure. Shielding the antennas from moisture with insulation didn't help. The only thing I found that helped was making another object the tallest sharpest point on the structure, or insulating or "rounding" the ends. One of the things I did with a fiberglass Super StationMaster was to drop a large plastic bucket over the sharp lightning spike at the top, and the noise all virtually vanished. Another was placing a copper toilet tank float ball on the top to make it smooth and round. Worked almost as well as the bucket. So did putting up a taller mast on a roof away from the VHF or UHF antenna. On one bank roof with a radio staion's remote brodcast pickup antenna and two way radio antenna, we just installed a metal flagpole about 50 feet away (they wouldn't let us have a pipe that protruded above the roofline as seen from the street, but they accepted and used the flagpole). I started listening to my antennas at home, and noticed the same thing. Lower antennas were always much more immune to what people call P-static. Now I'm not saying wind, dust, and moisture blowing across a well-insulated antenna won't charge it faster, and make an antenna without a ground path leak arc over some close gap more rapidly. I'm only saying I never have seen the noise pitch of what people commonly call P-static track the actual number of droplets or dust hitting the antenna, and everything else I've seen indicates the rapid popping that turns to a sizzle and then an almost musical pitch seems to be tied only to charge gradient between the antenna and the surrounding air. I've been on the top of very tall well-grounded BC towers on days with a stiff stready wind, no dust or rain, and seen a sharp bracket or sharp strand of guyline poking out hissing with corona streamers. That noise sounds just like what everyone I know calls "P-static". 73 Tom |
#44
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Cecil Moore wrote:
wrote: J. Mc Laughlin wrote: P-noise is observed when there is no rain nor thunderstorms, but plenty of wind. This is suggestive of moving charge discharging into the antenna. So how does it get there? How does it build up? Where is the spark arc or sizzle? This is a well known phenomenon in Arizona. What else, besides charged dust particles, could cause arcing at coax connectors on a perfectly clear windy day? A large scale demo of this effect can be seen during volcanic eruptions, when large amounts of dust are thrown into the atmosphere at high speeds. Lightning happens. http://www.guardian.co.uk/life/featu...368962,00.html It is not certainty, but particles rubbing against each other do a pretty good job of building up static. - 73 de Mike KB3EIA - |
#45
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![]() "Mike Coslo" wrote in message ... Cecil Moore wrote: wrote: J. Mc Laughlin wrote: P-noise is observed when there is no rain nor thunderstorms, but plenty of wind. This is suggestive of moving charge discharging into the antenna. So how does it get there? How does it build up? Where is the spark arc or sizzle? This is a well known phenomenon in Arizona. What else, besides charged dust particles, could cause arcing at coax connectors on a perfectly clear windy day? A large scale demo of this effect can be seen during volcanic eruptions, when large amounts of dust are thrown into the atmosphere at high speeds. Lightning happens. http://www.guardian.co.uk/life/featu...368962,00.html It is not certainty, but particles rubbing against each other do a pretty good job of building up static. - 73 de Mike KB3EIA - perfect example. a large scale dry example of colliding dust particles building an electric field, without need for them hitting a metalic conductor. dust particles pick up charge by bouncing off each other and the ground, there can actually be quite a high electric field built up. |
#46
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Dave wrote:
perfect example. a large scale dry example of colliding dust particles building an electric field, without need for them hitting a metalic conductor. dust particles pick up charge by bouncing off each other and the ground, there can actually be quite a high electric field built up. Is the charge on those dust particles electron based? When cave men rubbed amber on wool to charge it up, was that electrons? One time at a hotel in Odessa, TX, I walked across a wool carpet with leather shoes, went potty, and drew a two inch arc. OUCH! -- 73, Cecil http://www.qsl.net/w5dxp |
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