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Noise level between two ant types
Take 2 antennas on 6m - one is an inverted V and the
other a 3el quad. Both are mounted at near the same height and fed with about the same length of coax. Is it normal for the quad to be quieter? Signals are louder on the quad - it's just the background noise is higher on the V. Just curious..... -- 73's de Ken KG0WX - Kadiddlehopper #11808, Flying Pigs #-1055, Grid EM17io, FT-857D, AL-84, Elecraft XG2, 4SQRP Tenna Dipper, Heath GD-1B |
Noise level between two ant types
Ken Bessler wrote: Take 2 antennas on 6m - one is an inverted V and the other a 3el quad. Both are mounted at near the same height and fed with about the same length of coax. Is it normal for the quad to be quieter? Noise almost always arrives from multiple directions and from different directions than the desired signal. It is normal for ANY antenna to be quieter when it is more directional. As a matter of fact, it is expected that S/N ratio is a direct function of directivity of the antenna as long as the noise and signal are not coming from the same direction. To answer your question, it would be very abnormal if your quad (or Yagi or any other directional antenna) was noisier than a broad pattern antenna like your Inverted Vee dipole. By the way, a real Inverted V is a longwire array fed at one end. I'm assuming you really have an Inverted Vee dipole, and not a true Inverted V. 73 Tom |
Noise level between two ant types
Jim - NN7K wrote:
Not to mention that noise is normally a phenonmen of the Vertical Plane (which , depending on how steep your inverted "vee" is, will contain some vertical component, while the yagi/quad is Horizontal to the plane. Quads are a lot less noisy than Yagis when the wind is blowing in the Arizona desert. Quads have a DC short across the feedpoint that reduces noise from static buildup. -- 73, Cecil http://www.qsl.net/w5dxp |
Noise level between two ant types
Cecil Moore wrote: Quads are a lot less noisy than Yagis when the wind is blowing in the Arizona desert. Quads have a DC short across the feedpoint that reduces noise from static buildup. Virtually all Yagi's have dc paths to discharge the elements. The primary reason a quad is quiter is it has no sharp protruding ends that are sticking way out in the air. As a matter of fact if you research the quad, it was initially used to eliminate corona at radio station HCJB. Try this test, wire a small 2.5 MHh RF choke across your antenna and check the before and after noise levels. They will not change. 73 Tom |
Noise level between two ant types
wrote:
As a matter of fact if you research the quad, it was initially used to eliminate corona at radio station HCJB. Yep, designed by my distant cousin, BTW. Try this test, wire a small 2.5 MHh RF choke across your antenna and check the before and after noise levels. They will not change. Obviously a false statement based on limited knowledge and experience. Any ham living around Phoenix will be glad to enlighten you. That's exactly how I eliminated the noise and arcing on my first bare-wire G5RV installed in Arizona. I didn't measure the change in noise level but it went from arcing at the coax connector to not arcing at the coax connector which was acceptable to me. If the driven element on a Yagi is an uninsulated dipole, it is susceptible to wind driven noise on the driven element just like my G5RV was. Just because you have never experienced that type of noise in Georgia doesn't mean it doesn't exist in Arizona. I dare say you haven't experienced a lot of things that exist in reality. Mary G. comes to mind. :-) -- 73, Cecil http://www.qsl.net/w5dxp |
Noise level between two ant types
Cecil Moore wrote: Try this test, wire a small 2.5 MHh RF choke across your antenna and check the before and after noise levels. They will not change. Obviously a false statement based on limited knowledge and experience. When did you do that test? When did you compare other antennas, like noise on plummer's delight antennas? How many Yagi's have floating driven elements without ground paths? |
Noise level between two ant types
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Noise level between two ant types
Tom Ring wrote:
wrote: How many Yagi's have floating driven elements without ground paths? None on VHF/UHF/SHF that I build and anyone I know builds. Maybe on HF it's different. I don't know why it should be, though. Although normally all the other elements float on anything but 6 meters. You're both over-generalizing. In VHF/UHF/SHF yagi construction it's quite common to find driven elements connected to the boom or floating. The same choice or a different choice may be made for the parasitic elements. There are many different reasons for these choices, including: * size of elements and boom * mechanical strength requirements * effect of boom on element resonance (depends on mounting method) * long-term effect stability of element resonance * feed impedance of driven element (affects choice of feed method) * number of elements involved * perceived or actual effects of "static". This makes the choices quite complex, and makes generalization impossible. Quote an example, and someone else will quote you a counter-example. Just one other thing: PLEASE let's not talk about elements being "grounded", way up there at the top of a tower. -- 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
Noise level between two ant types
Ian White GM3SEK wrote: This makes the choices quite complex, and makes generalization impossible. Quote an example, and someone else will quote you a counter-example. Just one other thing: PLEASE let's not talk about elements being "grounded", way up there at the top of a tower. The entire topic and people's reactions about precepitation noise is fascinating. People actually seem to think the little particles voving through the air charge the antenna to a different potential than the air around the antenna, and that a "dc" path to earth or "dc" path around an element somehow magically stops RF noise. Certainly it is possible for a conductor very well insulated from earth to charge to the potential of the static field around the antenna, and flash over to "ground" through some path that breaks down. Of course only a fool would have equipment that allows that to happen while large antennas are being used or connected. This is an entirely different thing than the corona discharge that makes what people typically call "P-static". 73 Tom |
Noise level between two ant types
wrote:
Try this test, wire a small 2.5 MHh RF choke across your antenna and check the before and after noise levels. They will not change. Cecil Moore wrote: Obviously a false statement based on limited knowledge and experience. When did you do that test? Around 1990 to cure the arcing at the coax connector during clear-sky high-wind conditions in the Arizona desert. When I got rid of the coax and used ladder-line all the way to the tuner, I discovered that the 4:1 balun in the MFJ tuner accomplished the same anti-arcing function so hams using ordinary 4:1 voltage baluns are equalizing that charge before it can arc. When did you compare other antennas, like noise on plummer's delight antennas? The noise was the arcing of the coax connector at the input to my IC-745 which woke me up at night and scorched my rug after I disconnected it and laid it on the floor. Seems obvious that going from arcing to not arcing changes the noise level. I was afraid to turn the transceiver on during the arcing process. If I had known I was ever going to have this conversation with a doubting Thomas, I would have hung an o'scope on it. The condition is well known to most desert hams but I had just moved there from Silicon Valley. I never experienced the condition in Silicon Valley or East Texas. Installing the RF choke across the antenna feedpoint cured the problem. I'm not talking about plumber's delight antennas here. I am discussing Yagis and other antennas whose driven elements are center-fed dipoles where there is no DC path between the driven elements. How many Yagi's have floating driven elements without ground paths? It only takes one red car to disprove the assertion that all cars are white. All the Yagis that I have built used isolated dipole elements and it only takes one to demonstrate the clear- sky high-wind noise problems in the Arizona desert. Every Arizona desert ham running bare isolated HF elements with no DC path to ground will encounter the problem sooner or later. The problem has been discussed here on this newsgroup in the past, possibly while you weren't reading it. As I remember, one ham solved the problem with a 10K 3 watt carbon resistor across the feedpoint. It seems apparent to me that the problem occurs in very low humidity conditions. That would include dust and dry-air snow. And the dust doesn't have to be visible to the naked eye. I've seen it happen with clear-sky and seemingly clear-air conditions with high winds and low humidity. I suspect dust/pollen particles too small to see still carry a dry-air charge. -- 73, Cecil http://www.qsl.net/w5dxp |
Noise level between two ant types
Ian White GM3SEK wrote:
This makes the choices quite complex, and makes generalization impossible. Quote an example, and someone else will quote you a counter-example. Seems the assertion should be that precipitation noise can exist on some antennas but not on others. Just one other thing: PLEASE let's not talk about elements being "grounded", way up there at the top of a tower. How about "DC grounded"? -- 73, Cecil http://www.qsl.net/w5dxp |
Noise level between two ant types
wrote:
People actually seem to think the little particles voving through the air charge the antenna to a different potential than the air around the antenna, and that a "dc" path to earth or "dc" path around an element somehow magically stops RF noise. Please don't accuse people of believing in magic until you understand the physics involved. There's no magic involved. Dry-air dust and snow particles certainly can transfer a charge to an uninsulated wire in the air. It is simple physics to realize that when a highly charged particle touches a conductor, the charges between the two objects will be equalized. It would be magic if the particle and the wire did NOT equalize their charges by transferring excess differential charge when they come into contact. Given a dipole where one element has a DC path to ground and the other element is floating with respect to ground, it is reasonable to expect the charge between the two elements to be different and they often are. The difference in charge will build up to the point where the smallest gap between the two conductors arcs. In my configuration in the Arizona desert, that gap existed at the coax connector at the transceiver and it did indeed arc badly. It woke me up and scorched my rug after I disconnected it from my transceiver. The arc was bright enough to light up the room and certainly caused RF noise. The wind was blowing around 30 mph and there wasn't a cloud in the sky. Given an extreme relative charge between the element with a DC path to ground and the element without a DC path to ground, anything that will bleed off that charge will cure the problem. An RF choke works. A 4:1 voltage balun works. A resistor works. Perhaps we can convince a desert ham to hang an o'scope on a clear-sky, dry-air system on a windy day and report back here with some results. Many other hams have reported the same thing during a dry-air snow storm. -- 73, Cecil http://www.qsl.net/w5dxp |
Noise level between two ant types
wrote:
People actually seem to think the little particles voving through the air charge the antenna to a different potential than the air around the antenna, and that a "dc" path to earth or "dc" path around an element somehow magically stops RF noise. Let's say we have the following bare-wire dipole system link coupled to the receiver (in fixed font). | | dipole element A link coupled | -////- +--------------------------------------------------///////--+ | +-----------------------------------------------------------+ | | dipole element B | Let's assume one highly charged particle hits dipole element A and transfers half of its charge. Element A will then have an excess charge one half of which will migrate through the link while equalizing the charge between element A and element B. That charge migration/equalization no doubt results in an RF noise pulse. This experiment can easily be performed by anyone. Rub one's leather soles on a wool carpet, touch one side of the dipole, and listen for noise in the receiver. Guaranteed, it will be there. Now multiply the above by millions of charged particles randomly encountering the bare-wire dipole. The charge on each side of the dipole will never be exactly equal. Thus, continuous broad-band noise will be continuously transferred through the link as long as the particles are transferring charge to the antenna. That's what some hams are hearing during dry-air dust and snow conditions. Some have even reported being able to hear individual particle collisions from large snowflakes. -- 73, Cecil http://www.qsl.net/w5dxp |
Noise level between two ant types
Cecil Moore wrote:
Ian White GM3SEK wrote: This makes the choices quite complex, and makes generalization impossible. Quote an example, and someone else will quote you a counter-example. Seems the assertion should be that precipitation noise can exist on some antennas but not on others. Living in this climate, I don't have any particular view or experience about static noise (but ironically we're just about to get one of our few thunderstorms of the year... better go and do something about that). Just one other thing: PLEASE let's not talk about elements being "grounded", way up there at the top of a tower. How about "DC grounded"? By all means; so long as we never forget to include the "DC" part. -- 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
Noise level between two ant types
Ian White GM3SEK wrote:
Tom Ring wrote: wrote: How many Yagi's have floating driven elements without ground paths? None on VHF/UHF/SHF that I build and anyone I know builds. Maybe on HF it's different. I don't know why it should be, though. Although normally all the other elements float on anything but 6 meters. You're both over-generalizing. In VHF/UHF/SHF yagi construction it's quite common to find driven elements connected to the boom or floating. The same choice or a different choice may be made for the parasitic elements. There are many different reasons for these choices, including: * size of elements and boom * mechanical strength requirements * effect of boom on element resonance (depends on mounting method) * long-term effect stability of element resonance * feed impedance of driven element (affects choice of feed method) * number of elements involved * perceived or actual effects of "static". This makes the choices quite complex, and makes generalization impossible. Quote an example, and someone else will quote you a counter-example. Just one other thing: PLEASE let's not talk about elements being "grounded", way up there at the top of a tower. Maybe I should have defined what I meant when I said floating. I think we have been talking about a DC grounded element, and that's what I meant with respect to floating. Virtually all of the homebrew yagis that I have seen, and most of the commercial are gamma match, or T match. The gamma is not going to carry the ground through, but is used almost exclusively on 6 meters where driven elements are rarely insulated from the boom. 2 through 432 are T matches and that DC grounds the driven element regardless of how it's mounted. Going up we see mostly loop yagis, and I've never seen one of those that's not grounded. I know there are regular (non-loop) yagis used 902 and up, but I never seen one to see how they are driven. So, for me anyway, the generalization works. And I'm just watching Silverstone, Ian, so don't tell me how it went! tom K0TAR |
Noise level between two ant types
wrote:
I don't have a lifetime to spend picking nits with Cecil, but I do resent his immediate implications I haven't looked at the closely for a long time. Do you think the people who report the problems that you haven't experienced and don't understand resent your assertion that they believe in magic? The actual magical thinking is asserting that charged particles don't transfer part of their charge to bare wire antennas. In my experience the vast majority of noise people complain about is caused by corona from the element or something in the immediate area of the element. That may be true but we are not discussing corona noise. Exactly where do I go wrong in the following explanation? 1. A highly charged particle encountering one element of a bare copper wire dipole will transfer approximately half its charge to the wire. 2. A charge unbalance between the two elements of a dipole will cause a differential current to flow in a link coupled system. 3. The differential current may be detected by an RF receiver. Now I'm sure there will be some cases where people disagree with this, but anyone who can A-B-C test antennas will find that other than a pop or arc across a dielectric from antennas that accumulate enough charge to exceed charge leakage the only thing that really matters is how "pointed" the antenna is and how exposed the points are to the air around the antenna. This is simply a false statement. Many desert hams, like myself in the 1990's, have experienced another kind of noise. I've never experienced it from snow, but I can understand how it could happen with snow falling through dry air. The snow phenomenon has been reported here on this newsgroup. All that crud hitting the antenna isn't significantly different in potential than the air around the element, it just has a lower impedance. Absolutely false! Charged dust particles are a fact of life in the Arizona desert. There is often not enough moisture in the air to discharge them. Your limited experience is showing. How often does the relative humidity get down to 10% with high winds and dust in Georgia? As a matter of fact, it is rather silly to claim the particles discharging make noise and then at the same time claim that a DC path somehow reduces or eliminates that noise. I didn't claim it "reduces or eliminates that noise". I claimed it eliminates arcing which is certainly a type of noise. The CLOSER the antenna would be allowed to float to the potential of the particles the LESS change in potential would occur. Pulling the element to earth would make each tiny discharge worse and make more noise, not less. My problem was that 1/2 of the antenna was at DC ground potential and the other half was floating which is typical of a store-bought G5RV. That seems to cause the worst case of arcing. But it is simple physics to realize that each particle acts independently. The charge transfer from each particle causes a tiny differential current between the two elements of the antenna. Millions of unsynchronized collisions per second certainly would produce differential RF noise. A link-coupled balanced dipole system would probably never arc but there would be a differential noise pulse through the receiver as described in the graphic in my other posting. -- 73, Cecil http://www.qsl.net/w5dxp |
Noise level between two ant types
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Noise level between two ant types
Cecil Moore wrote: 1. A highly charged particle encountering one element of a bare copper wire dipole will transfer approximately half its charge to the wire. 2. A charge unbalance between the two elements of a dipole will cause a differential current to flow in a link coupled system. 3. The differential current may be detected by an RF receiver. Only when it is AT THE FREQUENCY the receiver is tuned to. So when you provide a DC path that does not short the antenna at radio frequencies, it does nothing. The only exception to this is if the charge actually causes something to arc, but even then it is a long term buildup of charge. This is simply a false statement. You can a call me a liar if you like, but it doesn't change the facts. All that crud hitting the antenna isn't significantly different in potential than the air around the element, it just has a lower impedance. Absolutely false! Charged dust particles are a fact of life in the Arizona desert. There is often not enough moisture in the air to discharge them. Your limited experience is showing. How often does the relative humidity get down to 10% with high winds and dust in Georgia? I haven't lived in Georgia all my life. Most of my experience with this is actually in Ohio, but on other reflectors like TowerTalk everyone seems to share the same common experiences. As a matter of fact, it is rather silly to claim the particles discharging make noise and then at the same time claim that a DC path somehow reduces or eliminates that noise. I didn't claim it "reduces or eliminates that noise". I claimed it eliminates arcing which is certainly a type of noise. We agree there. So why are you arguing? If it charges the antenna to the point where a dielectric fails the sudden change will make a terrible noise and may even cause damage. This is why no one should have a large element high in the air that does not have a leakage path. The CLOSER the antenna would be allowed to float to the potential of the particles the LESS change in potential would occur. Pulling the element to earth would make each tiny discharge worse and make more noise, not less. My problem was that 1/2 of the antenna was at DC ground potential and the other half was floating which is typical of a store-bought G5RV. That seems to cause the worst case of arcing. But it is simple physics to realize that each particle acts independently. The charge transfer from each particle causes a tiny differential current between the two elements of the antenna. Millions of unsynchronized collisions per second certainly would produce differential RF noise. In that case a ground on the floating side would make no difference, or if anything make it worse. Think about it, or draw it on paper. The charge differential (as you say above) is between the floating particles and the earth. The greater the charge difference, the larger the amount of charge transferred (as you said above). If we agree on what you say above, the "millions of unsynchronized collisions" would not impart less charge to the antenna when it is closer to earth potential, they would impart more. The fact is a dc path doesn't change a thing with one single exception, the dc path prevents an antenna from building a charge in the capaciatnce of the system, and prevents that voltage from building to the point where some dielectric fails. Indeed that happens, and that is why large high antennas should have a leakage path to earth. Even on a clear calm day my 160 dipole at 300 feet, if I let the coax dangle a few feet above earth, will knock a person for a loop when touched. Inactive power lines, when open circuited, have to be clamped to ground for the same reason. On a windy day the recharge rate of the dipole is faster, and faster still in inclement weather. When the weather is bad, there is corona off the antenna that makes a sizzling sound that starts out as a series of slow pops and builds to the point where it almost turns musical or tonal. If lightning flashes even far in the distance, it immediately stops and rebuilds. The higher the antenna and the sharper and more extended the ends, the worse the problem is. Even when no moisture is hitting the wire. 73 Tom |
Noise level between two ant types
wrote:
You can a call me a liar if you like, but it doesn't change the facts. Being ignorant doesn't make you a liar. The fact is that many hams have experienced charged particle noise. Your denial of such doesn't change the known facts. The meaning of most of your posting escapes me so I will just summarize my position. When I lived in the Arizona, clear-sky wind-driven charged dust particles transferred lots of energy to my bare-wire G5RV. It caused arcing whether the outside braid was grounded or not. It only happened when the wind was blowing and the humidity was very low. I'm not sure what your point of disagreement is so help me out. Do you agree that a charged particle will transfer energy to the bare wire in a dipole when it touches it? If not, why not? If the antenna were link coupled, do you agree that the above transferred energy will try to equalize between the two dipole elements? If not, why not? Do you agree that the equalizing of the charges between elements would cause a current to flow through the link? If not, why not? -- 73, Cecil http://www.qsl.net/w5dxp |
Noise level between two ant types
Jim - NN7K wrote: Not to mention that noise is normally a phenonmen of the Vertical Plane (which , depending on how steep your inverted "vee" is, will contain some vertical component, while the yagi/quad is Horizontal to the plane. This has been a factor on vhf for years, as noise levels tend to peak at 6 meters (50 MHz). The MAIN reason that F.M. is Vertical polarized is that for mobiles, it is easy to construct an omni-directional antenna. Most vhf manuals detail this effect! Jim NN7K Dunno...I don't see much difference as far as the polarity of the antenna. It's more the polarity of the noise source, and it's radiator. I've got both horizontal and vertical yagi's on 2m, and I've seen many times when the local line noise was much worse when horizontal. But I blame that on the noise being radiated mainly by horizontal power lines. I see cases of noise with both polarities, or mostly vertical, or mostly horizontal. Just depends on the source antenna. You usually see appx 20db attenuation when cross polarized. As far as Ken's loop vs inv vee, if the vee is picking up more noise, that just means the vee is the best antenna at picking up that particular noise and at that direction and angle. If he were to transmit on the two antennas, and receive them from the noise source, using the sources antenna, the vee would be received the strongest more than likely. It's all reciprical. Noise is rf just like any other signal, and obeys the same rules. If a certain antenna picks up more rf of any type, noise, or desired, it's the best antenna of the bunch to receive that source of rf. Thats one reason why I often chuckle about "noise problems".. As long as it's not local or common mode pickup from the shack, that just means the antenna is working, and doing what it's supposed to do. MK |
Noise level between two ant types
"Cecil Moore" wrote in message y.net... wrote: You can a call me a liar if you like, but it doesn't change the facts. Being ignorant doesn't make you a liar. The fact is that many hams have experienced charged particle noise. Your denial of such doesn't change the known facts. The meaning of most of your posting escapes me so I will just summarize my position. When I lived in the Arizona, clear-sky wind-driven charged dust particles transferred lots of energy to my bare-wire G5RV. It caused arcing whether the outside braid was grounded or not. It only happened when the wind was blowing and the humidity was very low. I'm not sure what your point of disagreement is so help me out. Youze guyz are arguing about two cases of "arcing" and going off on tangents. First case is as Cecil has experienced and 'splained, is the static electricity charge buildup and corresponding noise/discharge on conducting "things" due to charged particles - aka rubbing the glass rod with furry animal coat. The part (antenna) gets charge from the "rubbing" by the particles, air, whatever...., builds up voltage and is looking for discharge across anything that provides jumping points for the voltage accumulated. This is the case of clear Arizona skies, with no clouds in sight, just wind doing it's "thing". W8JI might not believe it, but it IS the fact. Second case is, as it was hotly discussed on Contest and other reflectors, and first mentioned by VE3BMV, W0UN, W4ZV and others, in conjunction with lightning and protection against it - is the static electricity charge buildup due to the clouds "rubbing" in the air and creating huge static charge between the clouds and the earth ground and objects "residing" on ground and connected to it. There the highest , mostly grounded, objects get "first crack" at the "touching" the voltage gradient generated by the static electricity buildup. If there is a sharp object, it will start "acting" by generating corona and "peacefully" discharging the potential. If it can't keep up with rate of "peaceful" charge, it will invite lightning strike. The corona can be visible at the times, or it doesn't have to be. Then we get cases when the high antenna is the highest object and will be the "discharger" and the noisiest one. That appears to discharge the charge from the area (space) in the vicinity of the high (object) antenna - umbrella. You can look at it as a capacitor plate, collecting charge from the space around it. Lower antennas get benefit of discharged space and are quiet. This is especially noticeable with stacked antennas. The top one would be typically 20/9 noise - hash, the lower one would be dead quiet. The same then applies when you have higher object than antenna in question, that antenna could be quiet, but when (beam) is aimed at the higher object (the static discharger) it can receive noise, but at much lower strength. This umbrella effect seems also work as a lightning prevention by discharging the space in the vicinity of the structure and preventing critical buildup of voltage causing creating of leader and inviting lightning strike (99.9%). I and others have noticed practical elimination of lightning strikes to our installation when sporting tall, grounded towers with large antennas (capacitor plates). They seem to bleed the deadly potential from the air "sandwich" between the sky (clouds) and ground and objects under the "umbrella" and making lightning look at pointy grounded objects before and after our "ugly" antennas and discharge their deadly megawatts there. So large antennas on tall towers - GOOD to repell lightning. Pointy, sharp objects - BAAAAD, they attract lightning. So, one can protect his QTH and radio junk by either inviting lightning to strike the lightning arresters and hopefully conduct them to ground, or better, repelling it by the Antenna Umbrella - the biggest mother antenna (capacitor plate) on the tallest possible and well grounded tower (no protruding VHF vertical pointy junk above) you can put up. Scientwists might not find this believable, but those with big towers and large grounded antennas noticed remarkable absence of direct lightning strikes vs. when previously sporting pointy verticals or towers without antennas on the top. When I had my TH6 at 60 ft. and above it, way up 2m Ringo Ranger on a mast, I got visited by direct lightning trice within 2 years. When put up Big Bertha with 60 ft boom Razors, never again over 10 years. Not very statistically scientific, but very noticeable. Same experienced by W0UN, W0ZV and others. Soooo, the judge's verdict is: Cecil is right, W8JI is partially right, jury to judge by the above 'splanation of this humble servant. :-) I hope this clears some static static. -- Yuri Blanarovich, K3BU, VE3BMV |
Noise level between two ant types
Cecil Moore wrote: When I lived in the Arizona, clear-sky wind-driven charged dust particles transferred lots of energy to my bare-wire G5RV. It caused arcing whether the outside braid was grounded or not. It only happened when the wind was blowing and the humidity was very low. But that effect is common no matter where we live. As I've said several times, a high dipole here for 160m charges enough to knock you on your rear on a calm sunny day if the coacial line is well insulated from ground. It is not wise tol have a large high antenna that was well-insulated from ground, since the accumulated charge can suddenly discharge through a series capacitor and damage equipment. Utility companies must ground unused wires that run for miles to prevent build up of charge, so that is not something that just occurs in arid climates. Do you agree that a charged particle will transfer energy to the bare wire in a dipole when it touches it? If not, why not? Of course it will IF it is at a different potential than the wire. If the antenna were link coupled, do you agree that the above transferred energy will try to equalize between the two dipole elements? If not, why not? Of course it will. Do you agree that the equalizing of the charges between elements would cause a current to flow through the link? If not, why not? Of course it will. I disagree wth your contention that the link, if the noise comes from each particle hitting the antenna, will reduce noise. That's the part that makes no sense. Maybe you can explain why the link (or folded element) would reduce that noise. 73 Tom |
Noise level between two ant types
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Noise level between two ant types
Bob Miller wrote: I have a low, 30 feet or so, 80 meter dipole fed with ladderline, through an mfj 989c tuner. Hot humid clime (Texas). Is the ground wire on the back of the tuner, going to a ground rod, enough to bleed off electrical build up? Almost anything is enough to do that. The charge rate is extremely low. My 318 foot tall insulated tower had a measured charge rate in the ten's of milliamperes as measured during approaching thunderstorms. Of course taking care of a lightning bolt or EMP from a lightning strike someplace around the area is another story. 73 Tom |
Noise level between two ant types
wrote:
Cecil Moore wrote: When I lived in the Arizona, clear-sky wind-driven charged dust particles transferred lots of energy to my bare-wire G5RV. It caused arcing whether the outside braid was grounded or not. It only happened when the wind was blowing and the humidity was very low. But that effect is common no matter where we live. As I've said several times, a high dipole here for 160m charges enough to knock you on your rear on a calm sunny day if the coaxial line is well insulated from ground. During the "H Field Antennas" thread, you said the following: ************************************************** ************* Reg Edwards wrote: Precipitation static, eg., from highly charged raindrops and fine snow or fine sand, impinging on the antenna wire, just causes an increase in receiver white noise level. It can be reduced but not removed by using a very thickly insulated antenna wire, like the inner conductor of a coaxial cable complete with its polyethylene jacket. ---- Reg. W8JI replied: I've never seen a case of precitation static occuring that way. In every single case I've seen, whether on tall buildings, tall towers, or antenna hear earth, it has always been corona discharges from the antenna or objects near the antenna. ... 73 Tom ************************************************** ************** I have only noticed the charged particle arcing in Arizona when the wind was blowing and that is what I am reporting. It is not wise to have a large high antenna that was well-insulated from ground, since the accumulated charge can suddenly discharge through a series capacitor and damage equipment. Where does the accumulated charge come from if not from charged particles? If the antenna is link coupled, the charge equalizes between the two dipole elements and, in my experience, doesn't arc. Do you agree that a charged particle will transfer energy to the bare wire in a dipole when it touches it? If not, why not? Of course it will IF it is at a different potential than the wire. If the antenna were link coupled, do you agree that the above transferred energy will try to equalize between the two dipole elements? If not, why not? Of course it will. Do you agree that the equalizing of the charges between elements would cause a current to flow through the link? If not, why not? Of course it will. Seems we are in agreement that charged particle RF noise can therefore be picked up by a receiver as Reg says above. It is only logical that it will be worse when the wind blows causing more charged particles to encounter the antenna wire. And, as shown below, it is only logical that a folded dipole would transfer less of that noise to the link than a non-folded dipole. I disagree with your contention that the link, if the noise comes from each particle hitting the antenna, will reduce noise. That's the part that makes no sense. In my experience, it eliminated the arcing. Thus it eliminated the *AURAL* arcing noise that my ears were hearing. Why does that make no sense? I was very clear that my receiver was off and disconnected at the time and that I made no RF noise measurements. A short, or 4:1 voltage balun, or choke, or link across the connector eliminated the *AURAL* arcing noise. Maybe you can explain why the link (or folded element) would reduce that noise. Seems you confused my statements about aural noise with RF noise. I have previously said I didn't measure the RF noise. In any case, please see the pictures below to understand why a folded element redirects the charge equalization process away from the link. The process of equalizing the charge on the non-folded dipole elements causes RF noise across the link which is picked up by the S-meter on the receiver. I observed that many times in AZ and wish I had made some measurements. The S-meter reports a higher level of charged particle noise during high wind conditions and dry-air snowstorms. Please explain what it is about the following that you don't understand. 1. The equalizing of the element charges on a link coupled dipole will cause a current to flow through the link resulting in higher RF noise readings on the S-meter during high wind conditions when more charged particles are encountering the antenna wire. 2. Turning the dipole into a folded dipole (or loop) gives a preferred localized path for the equalization of the charge. Not nearly as much RF noise current flows through the remote link. Maybe a picture would help. Here's a non-folded dipole with a charge hitting it. In order to equalize charge with the other element, part of the charge must flow down the transmission line, through the link, and back up the transmission line to the other dipole element. Virtually all of the pulsed charge equalization process goes through the link. ---------CH----+ +--------------- | | / / | | link ************************************************** ************** +--------------------------------+ +--------CH----+ +---------------+ | | / / | | link Here's a folded dipole with a charge hitting it in the same relative place. What is the most efficient preferred path for equalizing the charge with the other element? Not down the transmission line and through the link but simply straight through the antenna wire. Hint: Charge would rather take the 50 foot path of least resistance than a 200 foot path of most resistance. Eureka! The folded dipole is less noisy during high wind conditions than is the non-folded dipole because most of the charge equalization takes place locally through the antenna wire and not remotely through the link. BTW, thanks for forcing me to think this through in detail. -- 73, Cecil http://www.qsl.net/w5dxp |
Noise level between two ant types
Bob Miller wrote:
I have a low, 30 feet or so, 80 meter dipole fed with ladderline, through an mfj 989c tuner. Hot humid clime (Texas). Is the ground wire on the back of the tuner, going to a ground rod, enough to bleed off electrical build up? If there is a DC path to ground from *BOTH* sides of the dipole, the answer is yes. But, looking at the 989c schematic, I don't see a DC path to ground from one of the balanced line outputs. -- 73, Cecil http://www.qsl.net/w5dxp |
Noise level between two ant types
Cecil Moore wrote:
Bob Miller wrote: I have a low, 30 feet or so, 80 meter dipole fed with ladderline, through an mfj 989c tuner. Hot humid clime (Texas). Is the ground wire on the back of the tuner, going to a ground rod, enough to bleed off electrical build up? If there is a DC path to ground from *BOTH* sides of the dipole, the answer is yes. But, looking at the 989c schematic, I don't see a DC path to ground from one of the balanced line outputs. I forgot to say that your high humidity probably provides a path to ground from the other tuner terminal. It was only during super low humidity conditions in the Arizona desert that I experienced the arcing process during high winds. -- 73, Cecil http://www.qsl.net/w5dxp |
Noise level between two ant types
Cecil Moore wrote: wrote: Cecil Moore wrote: When I lived in the Arizona, clear-sky wind-driven charged dust particles transferred lots of energy to my bare-wire G5RV. It caused arcing whether the outside braid was grounded or not. It only happened when the wind was blowing and the humidity was very low. But that effect is common no matter where we live. As I've said several times, a high dipole here for 160m charges enough to knock you on your rear on a calm sunny day if the coaxial line is well insulated from ground. In the text above I was responding to the charging and arcing from a floating antenna, NOT to the mechanism Reg was talking about below. I have NO problem with the wire charging and arcing. But I've NEVER seen a situation where particles directly hitting the antenna make noise, which is what Reg was talking about below.... During the "H Field Antennas" thread, you said the following: ************************************************** ************* Reg Edwards wrote: Precipitation static, eg., from highly charged raindrops and fine snow or fine sand, impinging on the antenna wire, just causes an increase in receiver white noise level. It can be reduced but not removed by using a very thickly insulated antenna wire, like the inner conductor of a coaxial cable complete with its polyethylene jacket. ---- Reg. W8JI replied: I've never seen a case of precitation static occuring that way. In every single case I've seen, whether on tall buildings, tall towers, or antenna hear earth, it has always been corona discharges from the antenna or objects near the antenna. ... 73 Tom ************************************************** ************** I have only noticed the charged particle arcing in Arizona when the wind was blowing and that is what I am reporting. It is not wise to have a large high antenna that was well-insulated from ground, since the accumulated charge can suddenly discharge through a series capacitor and damage equipment. Where does the accumulated charge come from if not from charged particles? If the antenna is link coupled, the charge equalizes between the two dipole elements and, in my experience, doesn't arc. Why do you think it is the particle that make noise or even that they are necessary? Allowing what you say is true, then you are arguing against yourself. As I understand it: 1.) You say the particles make the noise as each individual particle hits the antenna. 2.) You say grounding the antenna eliminates that noise. There is an obvious conflict in those two ideas. Grounding the element for DC will not reduce the rate the rate of energy transfer to the antenna from particle, it can only INCREASE it by preventing long-term charging of the antenna closer to the potential of the particles. 73 Tom |
Noise level between two ant types
On Tue, 13 Jun 2006 15:43:29 GMT, Cecil Moore
wrote: Cecil Moore wrote: Bob Miller wrote: I have a low, 30 feet or so, 80 meter dipole fed with ladderline, through an mfj 989c tuner. Hot humid clime (Texas). Is the ground wire on the back of the tuner, going to a ground rod, enough to bleed off electrical build up? If there is a DC path to ground from *BOTH* sides of the dipole, the answer is yes. But, looking at the 989c schematic, I don't see a DC path to ground from one of the balanced line outputs. I forgot to say that your high humidity probably provides a path to ground from the other tuner terminal. It was only during super low humidity conditions in the Arizona desert that I experienced the arcing process during high winds. I can't recall seeing any gap-sparking here in the San Antonio area. When it's hot, it's usually pretty humid, too. bob k5qwg |
Noise level between two ant types
wrote:
Why didn't you respond to the pictures I drew for you? 1.) You say the particles make the noise as each individual particle hits the antenna. Yes, and you have agreed with all the steps leading up to that noise pulse flowing through the link. It is just simple physics. I notice you are not responding to any of the technical content of my posting are are continuing to deliberately obfuscate something I said earlier about aural arcing noise. 2.) You say grounding the antenna eliminates that noise. Grounding the antenna eliminated the ***AURAL*** arcing noise that was keeping me awake at night and scorching my rug when the transceiver was powered down and disconnected from the antenna. How many times do I have to explain that to you? But I have no doubt that if the transceiver had been turned on, the arcing across the transceiver connector would have caused RF noise if not failure. And I also have no doubt that grounding both transmission line conductors would have eliminated the arcing and thus reduced the RF noise heard by the receiver. Your style of argument is making you look stupid. There is an obvious conflict in those two ideas. Only in your mind, Tom. Please cease and desist with the obfuscation and try to follow your own advice from another newsgroup where you said nobody knows everything (presumably including you) and everyone is capable of learning something new (presumably including you). It's past time for you to learn about dry-air wind-driven charged-particle noise. Quantum Electrodynamics will tell you that even corona noise is caused by charged particles. -- 73, Cecil http://www.qsl.net/w5dxp |
Noise level between two ant types
Bob Miller wrote:
I can't recall seeing any gap-sparking here in the San Antonio area. When it's hot, it's usually pretty humid, too. If you have an o'scope, please hang it across the transmission line wires during your next dust storm and report the results compared to a calm day. -- 73, Cecil http://www.qsl.net/w5dxp |
Noise level between two ant types
Why didn't you respond to the pictures I drew for you?
Because you have unlimited time to go off into hunderds of a tangents. I still work 50-60 hours a week. 1.) You say the particles make the noise as each individual particle hits the antenna. Yes, and you have agreed with all the steps leading up to that noise pulse flowing through the link. It is just simple physics. I notice you are not responding to any of the technical content of my posting are are continuing to deliberately obfuscate something I said earlier about aural arcing noise. I must have missed it. With any AURAL noise there is alos a spark, and that spark is accompanied by electrical noise or component damage. My understanding was you said the HF noise in the receiver was caused by the random particles actually striking the antenna. If so, grounding makes no difference. 2.) You say grounding the antenna eliminates that noise. Grounding the antenna eliminated the ***AURAL*** arcing noise that was keeping me awake at night and scorching my rug when the transceiver was powered down and disconnected from the antenna. How many times do I have to explain that to you? Along with any aural noise is an arc, along with any arc is electrical noise. None of that matters however. As I understand it you said the HF noise was from particles hitting the antenna. If so, grounding the antenna could only increase the voltage delta between the particles and the antenna. If you disagree, explain why. But I have no doubt that if the transceiver had been turned on, the arcing across the transceiver connector would have caused RF noise if not failure. And I also have no doubt that grounding both transmission line conductors would have eliminated the arcing and thus reduced the RF noise heard by the receiver. If the noise was a slow popping noise caused by a series component breaking down, I agree. If the noise was what is commonly reffered to as P-static, the sizzling hissing or whining noise with almost a musical note, I disagree. Your style of argument is making you look stupid. Calling people stupid makes you look like you cannot have a mature discussion. Why not act mature? 73 Tom |
Noise level between two ant types
wrote:
I must have missed it. :-) Sure you did even after I said it half a dozen times. :-) You have talked about my transmission line laying on the rug scorching it so you could not possibly have "missed it". With any AURAL noise there is always a spark, and that spark is accompanied by electrical noise or component damage. Yes, I have said *many* times that my transceiver's power was off and it was unplugged from the transmission line. You know the transmission line was laying on my rug because you have talked about that before. My understanding was you said the HF noise in the receiver was caused by the random particles actually striking the antenna. If so, grounding makes no difference. I agree and never said otherwise. However, since you insist, below I indicate how grounding would have made a difference had I responded in a different way. If you disagree, explain why. Let's say that I was stupid enough not to disconnect my transceiver when I heard the arcing at the coax input and instead turned the transceiver on. Let's say it didn't suffer failure. Would you agree that I would hear RF noise in the transceiver every time the coax connector arced? Would you agree that if I shorted the center conductor to ground that since the outer conductor was already grounded, the RF noise in the transceiver would decrease? Why not act mature? It was you who once again regressed to your terrible-twos infantile omniscient stage and just couldn't resist misquoting me. Please don't do that again. -- 73, Cecil http://www.qsl.net/w5dxp |
Noise level between two ant types
Perhaps I'm not pedantic enough to enjoy the courtesy of your reply. If
your rug is scorched...how much current is there? My simple question was: Is this a novel way to create a trickle charger? (When TCVR is d/c'd, of course) Anyone care to respond? Otherwise, I'll just lurk and observe the "drama" between you two. John AB8WH |
Noise level between two ant types
jawod wrote:
Perhaps I'm not pedantic enough to enjoy the courtesy of your reply. I just checked back to your last posting to this thread. Here's what it said: Error! newsgroup server responded: Bad article number Perhaps the article has expired (272761) That's rather difficult to reply to. My simple question was: Is this a novel way to create a trickle charger? You could get some charge out of it but I just don't know how many joules per unit time. Perhaps someone out there in the desert could perform an experiment. -- 73, Cecil http://www.qsl.net/w5dxp |
Noise level between two ant types
Here's something similar Cecil:
I drove at 65 mph through a limited (about 1 mile wide) wind driven dust storm from an Iowa corn field during a drought. I was watching my S-meter on a 2m radio at the time (in the car). It slowly built up and eventually pinned (simultaneously, AM radio stations suffered the static build up and were blotted out. By the time I got through the mini-dust storm, the PIN diode antenna switching in the 2m radio had been destroyed. It was not raining. It was hot and dry, and you can imagine the dust particle count. I don't know the mechanics (as you people are disputing), but there was no doubt a significant build up and eventual discharge (I heard it on the AM radio) and the dust in the wind (thankyou Kansas), caused it, IMO. Another idiosyncratic report: 40m dipole up 30'. Middle of winter, very heavy wet snow. I could draw an arc off the end of the coax connector about an inch long. The rate of build/up and then discharge (how long it took between SNAPS) correlated very nicely with the rate of snowfall. The harder it snowed, the more rapidly the arc would happen, the more slowly it snowed, the longer in between arcing from the connector. Both of these, I would call "precip static"...one was dust, the other was snow. I'll leave it to you guys to figure out the mechanism. 73, ....hasan, N0AN "Cecil Moore" wrote in message . com... wrote: I must have missed it. :-) Sure you did even after I said it half a dozen times. :-) You have talked about my transmission line laying on the rug scorching it so you could not possibly have "missed it". With any AURAL noise there is always a spark, and that spark is accompanied by electrical noise or component damage. Yes, I have said *many* times that my transceiver's power was off and it was unplugged from the transmission line. You know the transmission line was laying on my rug because you have talked about that before. My understanding was you said the HF noise in the receiver was caused by the random particles actually striking the antenna. If so, grounding makes no difference. I agree and never said otherwise. However, since you insist, below I indicate how grounding would have made a difference had I responded in a different way. If you disagree, explain why. Let's say that I was stupid enough not to disconnect my transceiver when I heard the arcing at the coax input and instead turned the transceiver on. Let's say it didn't suffer failure. Would you agree that I would hear RF noise in the transceiver every time the coax connector arced? Would you agree that if I shorted the center conductor to ground that since the outer conductor was already grounded, the RF noise in the transceiver would decrease? Why not act mature? It was you who once again regressed to your terrible-twos infantile omniscient stage and just couldn't resist misquoting me. Please don't do that again. -- 73, Cecil http://www.qsl.net/w5dxp |
Noise level between two ant types
Cecil Moore wrote: :-) Sure you did even after I said it half a dozen times. :-) You have talked about my transmission line laying on the rug scorching it so you could not possibly have "missed it". I did NOT. You must have confused me with someone else. Would you agree that I would hear RF noise in the transceiver every time the coax connector arced? Absolutely. Would you agree that if I shorted the center conductor to ground that since the outer conductor was already grounded, the RF noise in the transceiver would decrease? Absolutely. So would the signals. S/N ratio would not change. |
Noise level between two ant types
I could draw an arc off the end of the coax connector about an inch long. The rate of build/up and then discharge (how long it took between SNAPS) correlated very nicely with the rate of snowfall. The harder it snowed, the more rapidly the arc would happen, the more slowly it snowed, the longer in between arcing from the connector. Both of these, I would call "precip static"...one was dust, the other was snow. I'll leave it to you guys to figure out the mechanism. Hasan, I think the problem here is there are two things at work. The first is a slow (compared to radio frequencies) build up of charge in an antenna that eventually breaks down a dielectric. I' like many people, have seen that many times. As a matter of fact that is common trigger for relay failures or SWR detector failures in systems without a leak impedance that leaks off charge faster than it builds. The second is what is commonly called P-static. As described earlier we had severe problems on tall tower and on the roofs of buildings. This is a noise that starts as a slow rapid hissing or buzzing that quickly builds almost to a musical tone as the weather gets more severe. This is the mechanisim I disagree with being caused by particles striking the antenna. The reason I disagree was clearly stated: 1.) Taller structures are affected much more than lower ones that are in the same weather 2.) Even one exposed protruding point seems to be the cause, since I could cover that point in Station Master antennas and make it go away, and it would go away by adding a taller blunt ended structure near the affected antennas. 3.) With identical antennas stacked on a single tower, the uppermost antenna is by far the most affected. 4.) I could get near the antennas and actually hear the accoustical noise that matched the noise on repeaters and actually see the corna ball. ....and on and on. Cecil then proposed, if I am not mistaken, that P-static was caused by particles striking the antenna, each one making a noise as it discharged into the antenna, and that noise could be reduced by grounding the element at DC. That is really the only point I disageed with. No one should even have a tall antenna or large antenna or any antenna that is subject to high levels of charge that does not have a leakage path to ground. That's just a given. But the idea a closed loop is somehow quieter than an open element that also has a leakage path makes no sense at all (especially when we are talking about noise from each particle) unless the antenna is: 1.) Lower 2.) More blunt 3.) Has less protruding ends My reasoning is the same number of charges hits each antenna, and the greater the potential difference between those changes and the antenna the greater the discharge power transfer to the antenna will be. So if the antenna were allowed to float to avarage potential of space around the antenna the noise from any energy transfer would actually be less. This excludes the big pop when a dielectric breaks down. My mobile antenna is matched by a shunt inductor, and that inductor prevents the coax from charging up with dc. However, that inductor does NOT make the antenna any more useful in weather like you described. It is every bit as noisy, absent the sporatic loud pops when a dielectric breaks down. Say I leak that antenna with a 20K resistor, and replace that resistor with a nearly zero ohm inductor that has high reactance at the operating frequency. There will be no noise change. The same applies to repeater antennas. We could use folded dipole elements, elements in fiberglass radomes, and so on. The only thing that helped was a blunter element or making the antenna lower in relation to some other object on the roof. We looked at dozens of systems hunderds of times, because no one wants communications to vanish in inclement weather. We never found a "dc grounded antenna" any help at all, although some leakage path probably would have stopped the diode failure you had...but not the noise. 73 Tom |
Noise level between two ant types
hasan schiers wrote:
Both of these, I would call "precip static"...one was dust, the other was snow. I'll leave it to you guys to figure out the mechanism. The behavior of charged particles has been understood for a century by most rational engineers and physicists. -- 73, Cecil http://www.qsl.net/w5dxp |
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