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Grounding my HF radio equipment
Hi, I did some searches on google for grounding, but all the
information I have found talks about grounding antennas and such against lightning strikes. But the grounding I am interested in researching is the type of ground I would use on my HF radio, power supply, and antenna tuner. I haven't grounded anything yet, but I would like to. I seem to have a hazy recollection of reading somewhere that I should use copper braid and connect it to the house ground. But during my search I found this image (which basically sums up the article it came from ) http://www.qsl.net/n5nj/kuby/image16.gif Does it really matter if my equipment is ground to the house ground or should it really be connected to its own external ground? And if/when I ground to guard against lightning strikes, would I use that same external ground or go with yet another external ground? I'm still doing my research, but figured it couldn't hurt to ask. Thanks! Jim |
Grounding my HF radio equipment
James Barrett wrote:
Does it really matter if my equipment is ground to the house ground or should it really be connected to its own external ground? And if/when I ground to guard against lightning strikes, would I use that same external ground or go with yet another external ground? I'm still doing my research, but figured it couldn't hurt to ask. Jim, You'll see numerous references on the web to "single point ground." It is very, very important stuff. I got nailed on this stuff back in August, 2003. Here's how it played out: We had a violent thunderstorm early one morning about 7 A.M. Suddenly there were three near strikes (simultaneous lightning and thunder) within a ten second time frame. In addition to telephones, computers and home entertainment equipment, my four month old Ten-Tec Orion and numberous shack accessories were zapped. My house ground is a single 8 foot copper plated ground rod. The lightning ground for the shack was an identical ground rod driven about thirty feet away from the house ground. When the strikes conducted a surge into my home via the power lines, all three wires had very high voltage on them. The shack ground was still at its usual potential (0). The house ground was elevated to high voltage. There was a potential difference between the shack ground the the house ground. That potential quickly equalized inside my equipment. Ten-Tec reported that six boards inside the Orion had their ground traces evaporated. For a shack ground, you want the shortest possible distance between your rig and earth. The house ground will be as close as possible to your electrical service entrance. If, like me, you have to use two ground rods, you need to bond the two of them together with a big, fat wire so that the two can never be at different potentials. If you have a tower, I'll assume that you have at least one 8 foot ground rod driven at its base. Bond your coaxial cable sheaths to the rod at the tower. The sheaths should also be bonded to your shack ground. Dave Heil K8MN |
Grounding my HF radio equipment
"James Barrett" wrote in message ... Hi, I did some searches on google for grounding, but all the information I have found talks about grounding antennas and such against lightning strikes. But the grounding I am interested in researching is the type of ground I would use on my HF radio, power supply, and antenna tuner. I haven't grounded anything yet, but I would like to. I seem to have a hazy recollection of reading somewhere that I should use copper braid and connect it to the house ground. But during my search I found this image (which basically sums up the article it came from ) http://www.qsl.net/n5nj/kuby/image16.gif Does it really matter if my equipment is ground to the house ground or should it really be connected to its own external ground? And if/when I ground to guard against lightning strikes, would I use that same external ground or go with yet another external ground? I'm still doing my research, but figured it couldn't hurt to ask. Thanks! Jim my own experence is that using the household ground at hf is marginal at best my own result were greatly inproved with aan extrenal seperat e ground |
Grounding my HF radio equipment
Hi James,
There are several good articles at the www.eham site on this very subject. If you can read between the lines of some of the muck slinging, you can come up with several really good solutions. Just click on the "view more articles" link [at the top of the horizontal green separator] HTH. Alain "James Barrett" wrote in message ... Hi, I did some searches on google for grounding, but all the information I have found talks about grounding antennas and such against lightning strikes. But the grounding I am interested in researching is the type of ground I would use on my HF radio, power supply, and antenna tuner. I haven't grounded anything yet, but I would like to. I seem to have a hazy recollection of reading somewhere that I should use copper braid and connect it to the house ground. But during my search I found this image (which basically sums up the article it came from ) http://www.qsl.net/n5nj/kuby/image16.gif Does it really matter if my equipment is ground to the house ground or should it really be connected to its own external ground? And if/when I ground to guard against lightning strikes, would I use that same external ground or go with yet another external ground? I'm still doing my research, but figured it couldn't hurt to ask. Thanks! Jim |
Grounding my HF radio equipment
Joaquin Tall wrote:
Hi James, There are several good articles at the www.eham site on this very subject. If you can read between the lines of some of the muck slinging, you can come up with several really good solutions. Just click on the "view more articles" link [at the top of the horizontal green separator] HTH. Alain "James Barrett" wrote in message ... Hi, I did some searches on google for grounding, but all the information I have found talks about grounding antennas and such against lightning strikes. But the grounding I am interested in researching is the type of ground I would use on my HF radio, power supply, and antenna tuner. I haven't grounded anything yet, but I would like to. I seem to have a hazy recollection of reading somewhere that I should use copper braid and connect it to the house ground. But during my search I found this image (which basically sums up the article it came from ) http://www.qsl.net/n5nj/kuby/image16.gif Does it really matter if my equipment is ground to the house ground or should it really be connected to its own external ground? And if/when I ground to guard against lightning strikes, would I use that same external ground or go with yet another external ground? I'm still doing my research, but figured it couldn't hurt to ask. There are two grounds for your radio system. There is an RF ground, and there is a power ground. They aren't the same, and even the term "ground" is a little nebulous. But it is convention. Dealing with the Power ground, you'll want to tie the grounds on the back of your radios/tuners/amplifiers together. There are a number of ways to do this. Some folks construct a copper ground plane that has wires running to it from the equipment needing grounded. Another possibility is wiring to the grounding bars such as are used for electrical service. This is the method I use. Whatever method used, short wires are better working practice. I'll just go over my own setup as beyond the grounding bar, you'll get a lot of opinions on what is right. I run heavy gauge wire out to a 8 foot copper pipe embedded about 7.5 feet into the ground, and have ground clamps to attach it. Braid is good too. Some other thoughts: I install the pipe hydrostatically - I sweat a garden hose adapter onto the copper pipe, attach a hose to it, and let 'er rip (hopefully no disclaimers needed here) The water digs a hole for the pipe, which then sinks into it. It's fun some folks ground to a water pipe. Not a good idea, as modern plumbing does not always have continuity - there might be a piece of PVC in the line somewhere. I have my Arrester going to that pipe also. I'm using a "spark gap" type arrester, but I would really recommend one of the gas discharge types. They are quick to respond, and better protection in general. Hope this helps. - 73 de Mike N3LI - |
Grounding my HF radio equipment
On Nov 27, 8:46 pm, Dave Heil wrote:
James Barrett wrote: Does it really matter if my equipment is ground to the house ground or should it really be connected to its own external ground? And if/when I ground to guard against lightning strikes, would I use that same external ground or go with yet another external ground? I'm still doing my research, but figured it couldn't hurt to ask. Jim, You'll see numerous references on the web to "single point ground." It is very, very important stuff. I got nailed on this stuff back in August, 2003. Here's how it played out: We had a violent thunderstorm early one morning about 7 A.M. Suddenly there were three near strikes (simultaneous lightning and thunder) within a ten second time frame. In addition to telephones, computers and home entertainment equipment, my four month old Ten-Tec Orion and numberous shack accessories were zapped. My house ground is a single 8 foot copper plated ground rod. The lightning ground for the shack was an identical ground rod driven about thirty feet away from the house ground. When the strikes conducted a surge into my home via the power lines, all three wires had very high voltage on them. The shack ground was still at its usual potential (0). The house ground was elevated to high voltage. There was a potential difference between the shack ground the the house ground. That potential quickly equalized inside my equipment. Ten-Tec reported that six boards inside the Orion had their ground traces evaporated. For a shack ground, you want the shortest possible distance between your rig and earth. The house ground will be as close as possible to your electrical service entrance. If, like me, you have to use two ground rods, you need to bond the two of them together with a big, fat wire so that the two can never be at different potentials. This whole topic area seems to be eternally confused and confusing and I'm in the parade of the confused. On a common sense basis I absolutely agree with your connecting the station grounds to the 'lectric service entrance ground for the reasons you've stated. But somewhere along the line somebody in the ham groups stated that the National Electrical Code states that there shall be one and *only one* grounding point per power drop and the neighborhood code cops and the insurance companies reportedly get stiff about it. So is it legal to connect a phalanx of ham station ground rods to the service entrance ground?? Or not. If you have a tower, I'll assume that you have at least one 8 foot ground rod driven at its base. Bond your coaxial cable sheaths to the rod at the tower. The sheaths should also be bonded to your shack ground. Dave Heil K8MN w3rv |
Grounding my HF radio equipment
In article ,
wrote: This whole topic area seems to be eternally confused and confusing and I'm in the parade of the confused. On a common sense basis I absolutely agree with your connecting the station grounds to the 'lectric service entrance ground for the reasons you've stated. But somewhere along the line somebody in the ham groups stated that the National Electrical Code states that there shall be one and *only one* grounding point per power drop and the neighborhood code cops and the insurance companies reportedly get stiff about it. So is it legal to connect a phalanx of ham station ground rods to the service entrance ground?? Or not. As I understand it, according to the NEC, you must have only one grounding *system* per building. This system may include two or more ground rods, and/or a bare grounding wire buried in a trench around the outside of the building. The ground rods and wires must be securely bonded together with heavy-gauge wire... that's what ensures that it's all one grounding "system". What's dangerous is, as has been suggested, having separate grounding rods (or grounding subsystems) which aren't well-bonded together. If you connect any electrical apparatus to two such grounding points (e.g. ham radio with a third-prong ground on its line cord, which is also tied to a separate ground rod via the coax feedline), and a lightning strike or a hot-to-ground fault occurs, your electrical apparatus and its wiring can end up carrying a lot of current between the ground points, thus creating a shock or fire hazard. The bonding wires create a low-impedance path for such fault currents, minimizing the voltage differential which exists between the ground rods and thus helping keep down the flow of fault current through undesired paths (e.g. your ham rig). -- Dave Platt AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
Grounding my HF radio equipment
Michael Coslo wrote:
There are two grounds for your radio system. There is an RF ground, and there is a power ground. They aren't the same, and even the term "ground" is a little nebulous. But it is convention. The is probably the biggest point of confusion for me. What do you mean by "RF ground"? The type of ground I was asking about is the ground terminal on the back of my radio,not the three prong power plug. There is the ground terminal on the back of my radio and there is also a ground terminal on my power supply, even though both have three prong power plugs. So, are the ground terminals on the back of my radio and power supply called RF ground, or are the called Power ground? Because I thought that the power ground was the three prong plug. Jim |
Grounding my HF radio equipment
In article ,
James Barrett wrote: The is probably the biggest point of confusion for me. What do you mean by "RF ground"? The type of ground I was asking about is the ground terminal on the back of my radio,not the three prong power plug. There is the ground terminal on the back of my radio and there is also a ground terminal on my power supply, even though both have three prong power plugs. So, are the ground terminals on the back of my radio and power supply called RF ground, or are the called Power ground? Because I thought that the power ground was the three prong plug. The intent of the third prong on the power plug is to provide a safe path from the equipment chassis, back to the power panel (where the neutral and hot are bonded together). This ensures that if there's a fault inside the equipment, and a "hot" wire touches the chassis, the stray current will immediately flow back to the panel via this ground connection (and likely cause a fuse to blow or a breaker to trip very quickly). It ensures that you don't end up with a chassis which is "hot", and isolated from ground... just waiting for somebody to touch it, accidentally complete a path to ground via their body, and get themselves mildly dead. The intent of the ground terminal on the back of the radio is to let you tie the radio chassis to a good RF ground, so that if any RF reaches the chassis via conduction (e.g. coming back down the feedline) it doesn't leave you with a chassis which is RF-hot compared to grounded objects nearby (this could cause an RF burn if you touch the chassis, or sneak back into the microphone wiring and cause weird squawking sounds when you transmit). It's also necessary if you plan to use a random-wire or similar unbalanced antenna which is designed to work against the station ground (e.g. radials or counterpoises). It's normally the practice to bond *all* of the equipment in your shack together with good (short, heavy) grounding wire or braid... once again, ensuring that different pieces of equipment have their chassis at the same (or nearly the same) AC and RF potential. By doing so, you are in effect bonding together your power/safety ground, and your station RF ground, creating a single ground system. Because this in-the-station ground bonding isn't really designed to handle massive amounts of fault current (e.g. from lighting) and since it's in an area where you really don't want such fault current to flow (e.g. your shack), it's still important to bond your station's "RF ground" rod, and your house's service-panel ground rod, together as per NEC. -- Dave Platt AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
Grounding my HF radio equipment
James Barrett wrote:
Michael Coslo wrote: There are two grounds for your radio system. There is an RF ground, and there is a power ground. They aren't the same, and even the term "ground" is a little nebulous. But it is convention. The is probably the biggest point of confusion for me. What do you mean by "RF ground"? It is confusing, so you're not alone. RF grounds can be related to Power grounds, but only so far. On say a ground plane antenna, where you have a vertical center rod connected to the coax center conductor, and some angled rods connected to the coax shield, those angled rods are serving as a ground plane. They aren't connected to actual earth. This is where a lot of the confusion comes in. The ground plane is more of a counterpoise, or to look at it as a circuit, a place for the other part of the current to go. Now if we look at say a vertical HF antenna of the 1/4 wave variety, typically this antenna will have "grounding" by way of many radial lengths of wire that are either buried in the earth at a shallow depth, or even just stapled to the surface of the earth. This is "Kind of-sort of" like a power ground, in that it is in the earth, but its doing something different. It is operating very similarly to that ground plane. It gives the RF current a place to go. I didn't go into things like impedence to avoid confusing the issue, but that would be next in the discussion. The type of ground I was asking about is the ground terminal on the back of my radio,not the three prong power plug. There is the ground terminal on the back of my radio and there is also a ground terminal on my power supply, even though both have three prong power plugs. So, are the ground terminals on the back of my radio and power supply called RF ground, or are the called Power ground? The ground terminals on your equipment are part of the power ground, that you would attach to the pipe in the yard. Explanation of that below. Any RF ground would be considered to be on the shield of the coax connectors. Because I thought that the power ground was the three prong plug. Yes, generally. One of the reasons that we put in a separate ground rod from house ground for a power ground is that there can be currents on it after going around the house. It's still mostly neutral, but with hundreds of feet of that green wire running around the house, you can still get some currents. Some people can "get away with" not having a station power ground. Kinda. I highly recommend one especially for some place to send your lightning protection. - 73 de Mike N3LI - |
Grounding my HF radio equipment
Dave Platt wrote:
The intent of the third prong on the power plug is to provide a safe path from the equipment chassis, back to the power panel (where the neutral and hot are bonded together). This ensures that if there's a fault inside the equipment, and a "hot" wire touches the chassis, the stray current will immediately flow back to the panel via this ground connection (and likely cause a fuse to blow or a breaker to trip very quickly). It ensures that you don't end up with a chassis which is "hot", and isolated from ground... just waiting for somebody to touch it, accidentally complete a path to ground via their body, and get themselves mildly dead. One of the reasons that Ground fault interrupters are around. If you have a hundred feet or even more of neutral wire going back to that panel, you can still get an appreciable current flowing through you without tripping a breaker. I've had my tookus saved by one of those GFCI things when a power tool failed in the manner you just described. I felt the shock for just a fraction of a second, then it tripped. the chassis, or sneak back into the microphone wiring and cause weird squawking sounds when you transmit). Ahh, that happens to me all the time even without RF on the mic! ;^) - 73 de Mike N3LI - |
Grounding my HF radio equipment
On Nov 29, 9:39 pm, (Dave Platt) wrote:
In article , .. . . . . So is it legal to connect a phalanx of ham station ground rods to the service entrance ground?? Or not. As I understand it, according to the NEC, you must have only one grounding *system* per building. This system may include two or more ground rods, and/or a bare grounding wire buried in a trench around the outside of the building. The ground rods and wires must be securely bonded together with heavy-gauge wire... that's what ensures that it's all one grounding "system". .. . . . . . . Makes complete sense and answers my basic question. Thank you David. I have five 8' ground rods already installed with more coming. All of them will be bonded together with about 100' of #8 bare solid copper. Let's try one mo This place is a "This Old House" type abode. There is no basement and no visible service entrance ground rod. There's a tight dirt crawl space under the place which I'm not about to even try to wiggle and squirm through to find the power wiring ground connection. If there is a ground it's the 3/4" copper water supply line from the street which pops up somewhere in the crawl space per normal practice in days of yore around here. I know for a fact that it's an old ~80' 100% copper line, not plastic. On the other hand the service entrance panel box is quite accessible. Would it be OK if I connected my ham grounding system to the neutral/ground bus in the panel box instead of to the water line?? -- Dave Platt AE6EO w3rv |
Grounding my HF radio equipment
wrote in message ... On Nov 27, 8:46 pm, Dave Heil wrote: James Barrett wrote: But somewhere along the line somebody in the ham groups stated that the National Electrical Code states that there shall be one and *only one* grounding point per power drop and the neighborhood code cops and the insurance companies reportedly get stiff about it. the NEC refering only to the household AC wring(soon hopefully to DC circuts at least according to the local electrical inspector our system for RF are another affair all together the inspector also aprooves the use if desired of seperate eletectal ground when service of more than one voltage and/ot freq is ainvolved in my case I have a houshold from the ower company enterance a seprate gorund for my various solar and wind systems 12-48 v DCdepending on the location plus the seperate Ground from my station most inspector in my experence would rather our rf system were not grounded in to the mais ground since they don't uderstand RF at all |
Grounding my HF radio equipment
On Nov 30, 11:05 am, Michael Coslo wrote:
wrote: There is a whole lot of misinformation regarding grounding. Understatement of the day . . . An interesting mental exercise is taking a tower say 50 feet from your house. According to some, in order to comply with NEC, the tower has to be grounded by sending a lead back to the house to that single ground point. I guess they want to insulate the tower base from ground - no ufer's here, thanks. Sounds like a disaster waiting to happen. Of course. Over the years I've dealt with a grand total of two lightning "events". I had a 70' 45G tower with a monster mast which was topped by a homebrewed clone of a 2M Ringo Ranger which went to 90+ feet. Lightning magnet. There was one ground rod alongside the concrete base which was bonded (clamped and silver soldered) to the tower by a 1/8" x 1/2" copper strap. There were three runs of coax, a run of shielded rotator cable and an unshielded run of 14/3 Romex up the tower with all shields and the Romex ground bonded to the tower. All the radio gear in the basement shack was grounded to the water line which was ~25' from the radios. Not slick by today's standards. Along came the first hit and my whole world turned "bright electric blue". Power line/brown underwear hit. The thunder was still rumbling loudly so I scrambled behind the gear and furiously got into yanking plugs out of outlets when *bang* another hit . . In the end there was all kinds of damage to the house wiring, TV sets and kitchen appliances toasted, second floor wall outlets atomized, etc. The only damage in the "radio room" was to the two vaporized disc ceramic AC line bypass caps in the 75A4. From this experience I learned that (a) lightning certainly can strike the same place twice in rapid succession and that (b) lightning can choose to hit power lines which are 30-40 feet *below* mongo grounded objects like a towers which makes no sense at all and (c) there are no manmade "cures" for lightning. Except maybe paid-up insurance coverage and prayer . . The good folks at Polyphaser have some excellent Technical notes. Kept me busy a long time reading the stuff: http://www.polyphaser.com/technical_notes.aspx Of particular interest is Ham Radio Station Protection: http://tinyurl.com/2aymw9 (tinyurl needed - its a long one) That's a really good one. I'll print it out and dig into it. Tank yew Michael. It is largely about lightning protection, but has good stuff pertaining to grounding. - 73 d eMike N3LI - w3rv |
Grounding my HF radio equipment
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Grounding my HF radio equipment
The intent of the third prong on the power plug is to provide a safe
path from the equipment chassis, back to the power panel (where the neutral and hot are bonded together). You do mean the neutral and ground, right? Erp. Yes, indeed! Bonding neutral and hot at the panel would be spectacular, but rather useless :-) -- Dave Platt AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
Grounding my HF radio equipment
konstans wrote:
wrote in message ... On Nov 27, 8:46 pm, Dave Heil wrote: James Barrett wrote: But somewhere along the line somebody in the ham groups stated that the National Electrical Code states that there shall be one and *only one* grounding point per power drop and the neighborhood code cops and the insurance companies reportedly get stiff about it. the NEC refering only to the household AC wring(soon hopefully to DC circuts at least according to the local electrical inspector our system for RF are another affair all together the inspector also aprooves the use if desired of seperate eletectal ground when service of more than one voltage and/ot freq is ainvolved in my case I have a houshold from the ower company enterance a seprate gorund for my various solar and wind systems 12-48 v DCdepending on the location plus the seperate Ground from my station most inspector in my experence would rather our rf system were not grounded in to the mais ground since they don't uderstand RF at all Any electrical contractor will tell you that not all electrical inspectors are well educated or trained. Ive had electrical inspectors state a preference for plastic boxes in a run of metallic conduit or cable. What those inspectors preferred was a direct violation of the National Electrical Code. I've had electrical inspectors try to order me to make a grounding connection in the meter enclosure which was totally unacceptable to the power utility and is not required by the NEC. I've had an electrical inspector fail my installation because I had made the Grounding Electrode Conductor connection to the service entry neutral conductor drip loop to comply with the requirements of the legacy Rural Electrification Administration (REA) power cooperative service standards even though the National Electrical Code specifically permits that location to be used. What the electrical inspector may prefer may be directly adverse to your best interest. Bond all of your Grounding Electrodes together even if your have to wait until after the electrical inspection to do so. -- Tom Horne "This alternating current stuff is just a fad. It is much too dangerous for general use." Thomas Alva Edison |
Grounding my HF radio equipment
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Grounding my HF radio equipment
On Dec 5, 6:48 pm, "Tom Horne, Electrician"
wrote: wrote: snip Let's try one mo This place is a "This Old House" type abode. There is no basement and no visible service entrance ground rod. There's a tight dirt crawl space under the place which I'm not about to even try to wiggle and squirm through to find the power wiring ground connection. If there is a ground it's the 3/4" copper water supply line from the street which pops up somewhere in the crawl space per normal practice in days of yore around here. I know for a fact that it's an old ~80' 100% copper line, not plastic. On the other hand the service entrance panel box is quite accessible. Would it be OK if I connected my ham grounding system to the neutral/ground bus in the panel box instead of to the water line?? -- w3rv It is not necessary to bring your bonding conductor to the inside of the panel cabinet. Bonding it to the cabinet itself is sufficient. I would have thought that would'nt be kosher. Good info If any portion of the Grounding Electrode Conductor is accessible then that is the best place to connect your inter electrode bonding conductor. Roger that. Thanks Dave. -- Tom Horne "This alternating current stuff is just a fad. It is much too dangerous for general use." Thomas Alva Edison Many yeards ago I read an article which stated that back in World War One days President Wilson convened an advisory council composed of a number of prominent Americans from different fields. Edison was a member. Somebody suggested that Einstein would make a good addition to the group. Edison's comment was something like "Somebody like Einstein might be handy to have around in case somethimg needs to be figured out." w3rv |
Grounding my HF radio equipment
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1 In writes: [...] Many yeards ago I read an article which stated that back in World War One days President Wilson convened an advisory council composed of a number of prominent Americans from different fields. Edison was a member. Somebody suggested that Einstein would make a good addition to the group. Edison's comment was something like "Somebody like Einstein might be handy to have around in case somethimg needs to be figured out." w3rv Sounds like an interesting story. No disrespect intended if I say that it sounds apocryphal, though many credulous-sounding stories do sometimes actually turn out to be true (see http://www.snopes.com for the straight skinny on many of them). Perhaps the basic back-story is true, but with one or more different players (see below). This one caught my eye, as someone who has a passing interest in American history from formal education in school, later personal reading of biographies by David McCullough, Steven Ambrose, etc., and from additional training that many Americans get: specifically, from watching hundreds of episodes of the game show "Jeopardy" :-). I was wondering if someone else with more expertise in the subject had some additional insight. Googling around doesn't seem to demonstrate that the story is true, nor does it demonstrate that the story is untrue. One thing that makes me suspicious is that for these three men (Wilson, Edison, Einstein) to have knowledge of one another in the way that the story suggests, their timelines, particularly the periods during which they were famous in the United States, would have had to significantly overlap. President Woodrow Wilson lived from 1856 to 1924 and served as President from 1913 to 1917. Thomas Edison lived from 1847 to 1931, and generally became famous as an inventor after the invention of the phonograph in 1877. Albert Einstein lived from 1879 to 1955, became well-known among physicists sometime during his famous, and initially controversial, research published from 1905 to 1915, won the Nobel Prize in 1921, visited the U.S. shortly afterwards, and eventually became well-known among most Americans (including Presidents) sometime after he emigrated to the U.S. in 1932, certainly sometime during or after World War II. Some points to ponder: - An early 20th Century U.S. President like Wilson might have been aware of American winners of the Nobel prize, but might he have been made aware of a still relatively obscure German/Swiss physicist before he left office in 1917, pre-Nobel? - Even if we assume that the President was Warren Harding (who was close to Thomas Edison, even camping out with him in Maryland during his presidency: http://www.ohiochannel.org/your_stat...&file_id=81864 Harding only served briefly from 1921 to 1923. A better match would be Herbert Hoover, who clearly was aware of Albert Einstein: http://www.presidency.ucsb.edu/ws/index.php?pid=22068 and served during the time that Thomas Edison was still alive: http://teachpol.tcnj.edu/amer_pol_hi...mbnail341.html - Hoover's successor, Franklin Delano Roosevelt (FDR), only became president in 1933, two years after Edison died in 1931. - Thomas Edison was a great inventor, but an individual without much formal education. Would he have necessarily been aware of what was going on in a theoretical academic field like Physics before 1917, and before Einstein had even done recognized works in that field? Recall that the General Theory of Relativity, published in 1915, was not widely accepted until years later, his Nobel Prize was for the Photoelectric Effect, and as a resident of one of the countries in the Central Powers (opposing the U.S., France, and the UK during WWI), his work would be censored from international publication during most of Wilson's term, anyway: http://en.wikipedia.org/wiki/Albert_...ral_relativity - The only reference I could find to Albert Einstein and Thomas Edison even just in communication with one another was this photograph from 1930: http://www.topfoto.co.uk/gallery/einstein/default.htm where Einstein telephoned Edison (from Germany) to congratulate him on the 50th anniversary of the invention of the electric light bulb, much later than Wilson's term of office. So, the timelines of Wilson, Edison, and Einstein don't really match up simultaneously. Nor do those of FDR match up with Edison, nor Wilson with Einstein. Either the President would have to be someone like Hoover or Harding, or the scientist would have to be someone else. At the very least, Einstein couldn't really be considered a "prominent American" until after he emigrated to the U.S. in 1932, and obtained U.S. citizenship in 1940. Ob Amateur Radio: Thomas Edison was a contemporary of Hiram Percy Maxim (co-founder of the ARRL), who lived from 1869 to 1936, and is credited with inventing the Maxim Silencer for firearms, and the automobile muffler. Hiram's father, Hiram Stevens Maxim, invented the machine gun, and was involved on the losing end of several patent disputes with Edison over the incandescent light bulb. - -- 73, Paul W. Schleck, K3FU http://www.novia.net/~pschleck/ Finger for PGP Public -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (SunOS) iD8DBQFHXJTP6Pj0az779o4RAgMpAJ0QH3dYWEBX5sO36DXG9g DnfdruCQCfesiG 9SCKrEUNu6VJ1UqCOSWWfaE= =tCeq -----END PGP SIGNATURE----- |
Grounding my HF radio equipment
The National Electrical Code (NEC) specifies that there be two
grounding points for a residential system. That can mean either two ground rods, six feet apart, connected to the panel with a continuous loop of wire, or a single ground rod in cases where there is municipal water, and the second ground source is the water main coming in, on the road side of the meter. The gas line also needs to be grounded to the panel. In the main service panel, the grounding system is attached to the same buss as the bare neutral coming in from the transformer. If your shack is running off a sub-panel, it should be fed with four conductor cable. In this case an insulated neutral is used and the bare (or insulated, it doesn't matter in this instance) ground is connected to a separate equipment ground buss. If your shack is in a separate structure that has its own sub panel, it needs to be fed with three conductor ground, the neutral is connected to the ground bar and a ground wire from a single ground rod is connected to the same buss (similar to the setup at the main panel). It sounds confusing as written here, and it's even more confusing to read it from the NEC, but I just had this out yesterday with my local inspector while going over the fine points on a job. All that NEC stuff is important to check to make sure you're setup is electrically safe. As for station grounding, it's not usually a good idea to use the electrical system ground rods for your RF grounds. Your rig, tuner, amps, etc, should all be grounded to a single buss with the shortest possible wires, then a large chunk of wire, #6 or better, should run as directly as possible to a separate 8' ground rod. If you have a tower, you should drive at least one 8 footer at the base and ground it there. There's no limit to the number of ground rods you can have for RF grounds, they're less than $10 from a distributor and well worth the effort. I've heard of hams setting up verticals with very minimal radials, just driving several ground rods. But somewhere along the line somebody in the ham groups stated that the National Electrical Code states that there shall be one and *only one* grounding point per power drop and the neighborhood code cops and the insurance companies reportedly get stiff about it. The answer to that is that if there is more than one they must be connected. The methods differ depending on the location of services in the structures and around the property. An electrician following the NEC would have done this during the installation and (hopefully) the inspector would have signed off on it. Ground rods for RF equipment SHOULD NOT be connected in any way to the electrical system ground rods. 73 KC2PNF Jon Dayton |
Grounding my HF radio equipment
BNB Sound wrote:
The National Electrical Code (NEC) specifies that there be two grounding points for a residential system. That can mean either two ground rods, six feet apart, connected to the panel with a continuous loop of wire, or a single ground rod in cases where there is municipal water, and the second ground source is the water main coming in, on the road side of the meter. The gas line also needs to be grounded to the panel. Grounding the gas line here would be an exercise in futility. A metal pipe goes into the ground just outside my home. It is three feet long. It then connects to a plastic gas line which goes under U.S. Route 250 and runs to a gas meter about 100 yards away. All that NEC stuff is important to check to make sure you're setup is electrically safe. As for station grounding, it's not usually a good idea to use the electrical system ground rods for your RF grounds. Your rig, tuner, amps, etc, should all be grounded to a single buss with the shortest possible wires, then a large chunk of wire, #6 or better, should run as directly as possible to a separate 8' ground rod. If you have a tower, you should drive at least one 8 footer at the base and ground it there. There's no limit to the number of ground rods you can have for RF grounds, they're less than $10 from a distributor and well worth the effort. That's a very, very bad idea. If your shack ground is not tied to your electrical ground and a near miss strikes power lines, the shack ground and your electrical ground will be at very different potentials. Your radio gear will be right in the middle. I've heard of hams setting up verticals with very minimal radials, just driving several ground rods. I've heard of it too, but it is another very bad idea. There is simply no way that driven ground rods can substitute for a radial screen. They are intended to do different things. But somewhere along the line somebody in the ham groups stated that the National Electrical Code states that there shall be one and *only one* grounding point per power drop and the neighborhood code cops and the insurance companies reportedly get stiff about it. The answer to that is that if there is more than one they must be connected. The methods differ depending on the location of services in the structures and around the property. An electrician following the NEC would have done this during the installation and (hopefully) the inspector would have signed off on it. Ground rods for RF equipment SHOULD NOT be connected in any way to the electrical system ground rods. That's simply incorrect and dangerous. I have connected my shack ground to my electrical ground with some great big honkin' copper wire. You may have as many different ground rods as you like. You should connect all of them to a single point. Dave K8MN |
Grounding my HF radio equipment
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Hash: SHA1 In Paul W. Schleck " writes: [...] President Woodrow Wilson lived from 1856 to 1924 and served as President from 1913 to 1917. [...] While true, it's also true that he served as President from 1917 to 1921. :-) Even in that sea of dates that I posted, I should have noticed that Wilson was not a one-termer, and did serve through World War I Armistice Day on November 11, 1918. - -- 73, Paul W. Schleck, K3FU http://www.novia.net/~pschleck/ Finger for PGP Public Key -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (SunOS) iD8DBQFHXhoD6Pj0az779o4RAv4OAJ92Ie3ckrn1Zeeepr/qXR81/Uv7sACfeJWt x0V2Ti+D7bWmu65LRk+AJ+w= =5L79 -----END PGP SIGNATURE----- |
Grounding my HF radio equipment
Dave Heil wrote:
BNB Sound wrote: I've heard of hams setting up verticals with very minimal radials, just driving several ground rods. I've heard of it too, but it is another very bad idea. There is simply no way that driven ground rods can substitute for a radial screen. They are intended to do different things. Correct. RF "grounding" is so different from Power ground that it shouldn't even be called the same thing. Good RF grounding can be had without a direct connection to the earth, my radials are insulated wire and don't have any wire exposure to the ground, so that they won't corrode. (note that the antenna gets direct connection to ground through the base. It sounded freaky weird to me at first, but as I put in my radials over several sessions (criteria being how long my poor abused knees could stand it) I measured and adjusted the system each time, and it worked as advertised. More radials = better grounding. The coil at the bottom of my vertical required less and less inductance to match the system. But it surely isn't a power ground, and given that the rf is absorbed (right word) at or near the ground surface, those ground rods would only be useful at that first foot or so. - 73 de Mike N3LI - |
Grounding my HF radio equipment
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