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Surge Suppressors for Long, Radiating Ground Conductors?
- Thread starter rfry
- Start date
W
WCWalker
Guest
Ermi Roos said:I sense some sort of pathology here. What seems to be needed is not technical analysis, but psychiatric analysis.
Correct. I noticed this many years ago and pointed it out to a couple of people outside of this board. I'm pleased to see that someone else that is a part of this board recognizes this.
R. Fry said:It would be more informative and useful to everyone if posts addressed provable technical issues, rather than subjective and personal opinion.
I'm confused by your selective nature in the above statement given your own previous statement,
R. Fry said:The reason for that is the "Chief Cook & Bottle Washer" of that website did not like the technical truths I had been posting there, even though he brands the site as "The Reference for Legal, Low Power, License-Free Radio."
When it was implied to me that my posts there might be edited or censored, and that there were a lot of buttons that could be pushed, there was no incentive for me to continue posting on that website.
I can almost understand your thinking about the surge supressers even though some of your explaination is as clear as mud but at least from what i can grasp the suppresser will do what they are suppose to do in making the safety of the transmitter workable. For the life of me i dont understand why you enjoy playing the part of the anti-Part15 warlord.
rob
Rob Martin said:I'm confused by your selective nature in the above statement given your own previous statement, <clip>
It wasn't technical, but it was a truthful statement to show why I don't post on that website, as had been noted previously in this thread by Mr Roos.
from what i can grasp the suppresser will do what they are suppose to do in making the safety of the transmitter workable.
To simplify my earlier posts on this, if a gas-tube suppressor is installed in series at the transmitter r-f ground terminal, that will prevent radiation from the ground wire -- which, in elevated installations provides most of the radiation from the system. In addition, the suppressor may not provide adequate lightning protection.
i dont understand why you enjoy playing the part of the anti-Part15 warlord.
Providing accurate information about the way Part 15 systems operate cannot accurately be described as being "anti-Part 15."
Earlier in this thread is this quote from Mr Roos first appearing on another board:
Indeed, the transmitter would not work at all without these parallel RF paths, because you can't drive a monopole from only the bottom end without a return path for the displacement current from the antenna to the cold side of the transmitter output. Transmitters that have been cited for long ground leads have continued to work (although with lower range) with the official ground lead disconnected, at higher field strength than they would have had at the level of the earth. This is because of the higher radiation resistance antennas have in elevated installations because of the parallel paths to ground which were apparently not taken into account by the FCC inspectors.
Just to note to Mr Roos (especially) that the red circle in the NEC-2D analysis I posted earlier in this thread at http://i62.photobucket.com/albums/h85/rfry-100/Part_15_AM_Surge_Suppressor_Effect.gif excludes parallel paths to ground supplied by power, and program audio wires.
However this does not prevent all radiation from such an elevated system as alleged by Mr Roos, because however short, the circuital "ground" conductors within the transmitter convert the 3-meter monopole to an off-center-fed dipole -- which is a configuration that by itself can radiate EM energy.
This point is evident in the NEC analysis referenced above.
Indeed, the transmitter would not work at all without these parallel RF paths, because you can't drive a monopole from only the bottom end without a return path for the displacement current from the antenna to the cold side of the transmitter output. Transmitters that have been cited for long ground leads have continued to work (although with lower range) with the official ground lead disconnected, at higher field strength than they would have had at the level of the earth. This is because of the higher radiation resistance antennas have in elevated installations because of the parallel paths to ground which were apparently not taken into account by the FCC inspectors.
Just to note to Mr Roos (especially) that the red circle in the NEC-2D analysis I posted earlier in this thread at http://i62.photobucket.com/albums/h85/rfry-100/Part_15_AM_Surge_Suppressor_Effect.gif excludes parallel paths to ground supplied by power, and program audio wires.
However this does not prevent all radiation from such an elevated system as alleged by Mr Roos, because however short, the circuital "ground" conductors within the transmitter convert the 3-meter monopole to an off-center-fed dipole -- which is a configuration that by itself can radiate EM energy.
This point is evident in the NEC analysis referenced above.
Ermi Roos said:You just don't give up, do you?
Not when a significant need exists to supply technically accurate information in a public forum, in response to previous posters there who (apparently) did not consider such.
Benjamin Franklin discovered this long before Part 15 systems existed, leading to his invention of lightning rods to protect elevated structures. Such lightning rods need to be permanently / continuously connected to a good earth ground by low impedance conductors.
If I remember correctly, one thing that Ben did not take into account was that a properly grounded and linked lightning system actually reduces the probability of a strike by bleeding off charges. Not saying a strike could not occur.
If I remember correctly, one thing that Ben did not take into account was that a properly grounded and linked lightning system actually reduces the probability of a strike by bleeding off charges. Not saying a strike could not occur.
Because of the uncertain (statistical) nature of lightning strikes, there are differences in opinion, even today, about the function of Ben's invention. Benjamin had a truly scientific attitude, and based on his own obsevations, he changed his mind at times about the function of the lightning rod.
The lightning rod is supposed to shunt the high current produced by a lightning strike harmlessly through a low conductance path, instead of through the wood, masonry, or stone of a building. Over nearly three centuries, however, it has been objected that the sharp-tipped lightning rod actually initiates lightning strikes, increasing the danger. The sharp tip has been replaced at times with rounded or flattened tips. This is because it is unclear what is the best thing to do.
The lightning rod is supposed to shunt the high current produced by a lightning strike harmlessly through a low conductance path, instead of through the wood, masonry, or stone of a building. Over nearly three centuries, however, it has been objected that the sharp-tipped lightning rod actually initiates lightning strikes, increasing the danger. The sharp tip has been replaced at times with rounded or flattened tips. This is because it is unclear what is the best thing to do.
Ermi Roos said:... it has been objected that the sharp-tipped lightning rod actually initiates lightning strikes, increasing the danger. The sharp tip has been replaced at times with rounded or flattened tips.
Sharp tips on lightning rods provide lower-resistance discharge paths for electrostatic charges than those having rounded tips, assuming in all cases the rods have the same, low-impedance paths to the physical earth.
Such sharp-tipped discharge paths mean that there will be less chance for the accumulation of static charges on the protected hardware to initiate a lightning strike in the first place.
This reality about rounded tips could be quite a shock, to some.
The link below leads to a commercial lightning protection product line using devices with such sharp tips, from a manufacturer of broadcast system towers, antennas and accessories.
http://www.eriinc.com/Catalog/Towers/Components-and-Accessories/Lightning-Dissipation-Spur.aspx
Ermi Roos said:As I said, there are considerable differences in opinion about this subject, and the linked advertisement differs greatly from other sources.
Mr Roos: Would you mind posting even one reference to scientifically-defensible theories supporting the opinion that rounded tips on lightning rods are (or might be) preferable to sharp tips on lightning rods?
Well my pea sized brain learned years ago that a large spherical shaped surface accumulates a charge more-so than a sharp point.
Ermi Roos said:Tesla, US Patent 1,266,175 1918.
Thanks. That was a new and interesting read for me, with a surprising premise and conclusion.
Probably no-one, including me cares to conclude whether Tesla or Franklin was more correct in their design for lightning rods. But it should be noted that pointed lightning rods are far more commonly used than the rounded type described by Tesla.
Maybe a statement in Tesla's patent is applicable to this, where he wrote about a pointed lightning rod,note "on the whole, its power of preventing injury predominates, more or less, over the hazards it invites."
note: Page 2, lines 102-105
Likewise, a nice read.
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