Re: Topband: OT - Bonding Radials at Intersections
You save me a lot of writing. This is my thought experiment. Just another point or two. 1) the more radials there are the lower the current in each. With enough radials, the currents are milliamps, unless you're running the megawatts I spoke of earlier. 2) If there are two (or more) verticals, the power divides and there is even less current per radial. Now consider two verticals driven in phase. The radial currents will also be in phase and even if they cross there is no voltage difference between them so there is no arc. You can tie them together if you like but it serves no function other than to change the resonant frequency of the shortened radials and upset the current distribution. Yes, they do have a resonant frequency, they are after all open ended transmission lines. Now consider the case where the verticals are driven out of phase. The radial currents are also out of phase and there will a maximum voltage gradient between them. This however, is the DESIRED condition. Short the ends together and you upset the phasing. I have no idea how significant this is, as I said this is a thought experiment not a thesis. Wes N7WS On 11/6/2020 10:43 PM, Jeff Blaine wrote: I of course defer to Frank's expertise here. But after thinking about this for a couple of hours, I'm trying to wrap my head around this arc risk concept as well. It's interesting and I toss this comment out because my two sets of 4sq don't have a single cross-bonded wire anywhere - all the ground structure is ground mounted, with overlapping wires literally all over the place. And despite that, the do seem to work more or less OK, as far as I can tell. I guess my thinking is list this... All those radial wires are laying out on the ground. So they are at least connected at some point, at a DC level, assuming your talking about something conventional like a 4SQ. Of course, we are talking about AC here, so I will agree that maybe the conditions could exist where - with just the right configuration between the two radials - that some larger than expected voltage differential may be present. Given how low Q a 4SQ is, how current is split between multiple elements, my gut feeling is that the excitation voltages are pretty mild even if you have your 1500W source right there at the 4SQ input. And on top of that, the wires are laying on the ground, right? The radials are in more or less intimate contact with the ground, so I would expect there to exist leakage resistance between adjacent conductors (if they are bare). And if they are perfectly insulated, this being AC, that means there is going to be some amount of cap coupling between adjacent wires and to the ground. With all of that R spread out all over the field, I would certainly think this conspires to work against the probability that any two optimally aligned individual crossing conductors would provide a condition sufficient to support an arc, and that if so, it would survive long enough to cause a fire. It's very very very dry here in the summer and again in the winter. So fire risk is something we keep a real close eye on. Then again, out here in the Midwest some of us do a lot of IL-advised things because they seem to work and of course because laziness is a BIG part of the calculation. ha ha. Maybe we have been taking a walk on the wild side without realizing it. Hope not because I sure don't want to go try to rectify this poor decision 3 years post installation! Say it ain't so! 73/jeff/ac0c alpha-charlie-zero-charlie www.ac0c.com _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: OT - Bonding Radials at Intersections
Wow, that's amazing. I suppose the risk of micro arcing then specifically with insulated radials has got to be closer to zero - at least until the insulation breakdown was sufficient to facilitate the arcing. If that's a reasonable guess, then maybe guys like me - who are from the start not going to cross connect - would have some benefit from the use of insulated wire in that it would side step this issue for the most part? In any event, when I do get around to building my personal MW station - needed in anticipation of the zombie apocalypse - for THAT set of radials, I will definitely plan on doing the cross connect work! 73/jeff/ac0c alpha-charlie-zero-charlie www.ac0c.com On 11/7/20 12:39 AM, donov...@erols.com wrote: Hi Jeff, Micro arcing can be excited by just a few volts of RF. While micro arcing probably is n't a fire risk, micro arcing radiates low level phase noise on transmitted signals. This is can cause a serious interference problem to nearby receivers such as neighboring hams or co-located receivers such an in-band receiver in a contest station. I personally experienced these problems with megawatt transmitters. In one instance, a massive radial system for a one mile long of array of HF phased verticals had to be completely replaced because it generated an elevated noise floor that degraded the performance of the HF over the horizon radar. In another case a poorly engineered, badly installed and inadequately maintained radial system for a 500 kw VLF system caused severe television interference to neighbors that forced premature site closure. 73 Frank W3LPL - Original Message - From: "Jeff Blaine" To: topband@contesting.com Sent: Saturday, November 7, 2020 5:43:25 AM Subject: Re: Topband: OT - Bonding Radials at Intersections I of course defer to Frank's expertise here. But after thinking about this for a couple of hours, I'm trying to wrap my head around this arc risk concept as well. It's interesting and I toss this comment out because my two sets of 4sq don't have a single cross-bonded wire anywhere - all the ground structure is ground mounted, with overlapping wires literally all over the place. And despite that, the do seem to work more or less OK, as far as I can tell. I guess my thinking is list this... All those radial wires are laying out on the ground. So they are at least connected at some point, at a DC level, assuming your talking about something conventional like a 4SQ. Of course, we are talking about AC here, so I will agree that maybe the conditions could exist where - with just the right configuration between the two radials - that some larger than expected voltage differential may be present. Given how low Q a 4SQ is, how current is split between multiple elements, my gut feeling is that the excitation voltages are pretty mild even if you have your 1500W source right there at the 4SQ input. And on top of that, the wires are laying on the ground, right? The radials are in more or less intimate contact with the ground, so I would expect there to exist leakage resistance between adjacent conductors (if they are bare). And if they are perfectly insulated, this being AC, that means there is going to be some amount of cap coupling between adjacent wires and to the ground. With all of that R spread out all over the field, I would certainly think this conspires to work against the probability that any two optimally aligned individual crossing conductors would provide a condition sufficient to support an arc, and that if so, it would survive long enough to cause a fire. It's very very very dry here in the summer and again in the winter. So fire risk is something we keep a real close eye on. Then again, out here in the Midwest some of us do a lot of IL-advised things because they seem to work and of course because laziness is a BIG part of the calculation. ha ha. Maybe we have been taking a walk on the wild side without realizing it. Hope not because I sure don't want to go try to rectify this poor decision 3 years post installation! Say it ain't so! 73/jeff/ac0c alpha-charlie-zero-charlie www.ac0c.com On 11/6/20 10:59 PM, donov...@erols.com wrote: Always beware of any communication that begins "with all due respect" - Original Message - From: "Wes" To: topband@contesting.com Sent: Saturday, November 7, 2020 4:49:23 AM Subject: Re: Topband: OT - Bonding Radials at Intersections With all due respect, I must ask, how many megawatts are you guys running? Wes N7WS On 11/6/2020 3:26 PM, donov...@erols.com wrote: Hi Carl, If the insulation breaks down they will arc, potentially causing a fire 73 Frank W3LPL On 11/6/2020 4:27 PM, Richard (Rick) Karlquist wrote: On 11/6/2020 1:10 PM, Carl Clawson wrote: Frank, “Must” is a strong word. What goes wrong if you cross them? 73, Carl WS7L Also, if insulated wires are used for radials that cross over each other, is that to be treated differently th
Re: Topband: OT - Bonding Radials at Intersections
Hi Jeff, Micro arcing can be excited by just a few volts of RF. While micro arcing probably is n't a fire risk, micro arcing radiates low level phase noise on transmitted signals. This is can cause a serious interference problem to nearby receivers such as neighboring hams or co-located receivers such an in-band receiver in a contest station. I personally experienced these problems with megawatt transmitters. In one instance, a massive radial system for a one mile long of array of HF phased verticals had to be completely replaced because it generated an elevated noise floor that degraded the performance of the HF over the horizon radar. In another case a poorly engineered, badly installed and inadequately maintained radial system for a 500 kw VLF system caused severe television interference to neighbors that forced premature site closure. 73 Frank W3LPL - Original Message - From: "Jeff Blaine" To: topband@contesting.com Sent: Saturday, November 7, 2020 5:43:25 AM Subject: Re: Topband: OT - Bonding Radials at Intersections I of course defer to Frank's expertise here. But after thinking about this for a couple of hours, I'm trying to wrap my head around this arc risk concept as well. It's interesting and I toss this comment out because my two sets of 4sq don't have a single cross-bonded wire anywhere - all the ground structure is ground mounted, with overlapping wires literally all over the place. And despite that, the do seem to work more or less OK, as far as I can tell. I guess my thinking is list this... All those radial wires are laying out on the ground. So they are at least connected at some point, at a DC level, assuming your talking about something conventional like a 4SQ. Of course, we are talking about AC here, so I will agree that maybe the conditions could exist where - with just the right configuration between the two radials - that some larger than expected voltage differential may be present. Given how low Q a 4SQ is, how current is split between multiple elements, my gut feeling is that the excitation voltages are pretty mild even if you have your 1500W source right there at the 4SQ input. And on top of that, the wires are laying on the ground, right? The radials are in more or less intimate contact with the ground, so I would expect there to exist leakage resistance between adjacent conductors (if they are bare). And if they are perfectly insulated, this being AC, that means there is going to be some amount of cap coupling between adjacent wires and to the ground. With all of that R spread out all over the field, I would certainly think this conspires to work against the probability that any two optimally aligned individual crossing conductors would provide a condition sufficient to support an arc, and that if so, it would survive long enough to cause a fire. It's very very very dry here in the summer and again in the winter. So fire risk is something we keep a real close eye on. Then again, out here in the Midwest some of us do a lot of IL-advised things because they seem to work and of course because laziness is a BIG part of the calculation. ha ha. Maybe we have been taking a walk on the wild side without realizing it. Hope not because I sure don't want to go try to rectify this poor decision 3 years post installation! Say it ain't so! 73/jeff/ac0c alpha-charlie-zero-charlie www.ac0c.com On 11/6/20 10:59 PM, donov...@erols.com wrote: > Always beware of any communication that begins "with all due respect" > > - Original Message - > > From: "Wes" > To: topband@contesting.com > Sent: Saturday, November 7, 2020 4:49:23 AM > Subject: Re: Topband: OT - Bonding Radials at Intersections > > With all due respect, I must ask, how many megawatts are you guys running? > > Wes N7WS > > > On 11/6/2020 3:26 PM, donov...@erols.com wrote: >> Hi Carl, >> >> >> If the insulation breaks down they will arc, potentially causing a fire >> >> >> 73 >> Frank >> W3LPL >> >> On 11/6/2020 4:27 PM, Richard (Rick) Karlquist wrote: >>> On 11/6/2020 1:10 PM, Carl Clawson wrote: >>>> Frank, >>>> >>>> “Must” is a strong word. What goes wrong if you cross them? >>>> >>>> 73, Carl WS7L >>>> >>> Also, if insulated wires are used for radials that cross >>> over each other, is that to be treated differently than bare >>> metal wires that cross over each other and touch >>> so as to have electrical connectivity? >>> >>> Does it matter if cross over radials are soldered at the >>> crossovers, so as to prevent parasitic "diodes". >>> >>> For whatever weird reason, the price of insulated
Re: Topband: OT - Bonding Radials at Intersections
I of course defer to Frank's expertise here. But after thinking about this for a couple of hours, I'm trying to wrap my head around this arc risk concept as well. It's interesting and I toss this comment out because my two sets of 4sq don't have a single cross-bonded wire anywhere - all the ground structure is ground mounted, with overlapping wires literally all over the place. And despite that, the do seem to work more or less OK, as far as I can tell. I guess my thinking is list this... All those radial wires are laying out on the ground. So they are at least connected at some point, at a DC level, assuming your talking about something conventional like a 4SQ. Of course, we are talking about AC here, so I will agree that maybe the conditions could exist where - with just the right configuration between the two radials - that some larger than expected voltage differential may be present. Given how low Q a 4SQ is, how current is split between multiple elements, my gut feeling is that the excitation voltages are pretty mild even if you have your 1500W source right there at the 4SQ input. And on top of that, the wires are laying on the ground, right? The radials are in more or less intimate contact with the ground, so I would expect there to exist leakage resistance between adjacent conductors (if they are bare). And if they are perfectly insulated, this being AC, that means there is going to be some amount of cap coupling between adjacent wires and to the ground. With all of that R spread out all over the field, I would certainly think this conspires to work against the probability that any two optimally aligned individual crossing conductors would provide a condition sufficient to support an arc, and that if so, it would survive long enough to cause a fire. It's very very very dry here in the summer and again in the winter. So fire risk is something we keep a real close eye on. Then again, out here in the Midwest some of us do a lot of IL-advised things because they seem to work and of course because laziness is a BIG part of the calculation. ha ha. Maybe we have been taking a walk on the wild side without realizing it. Hope not because I sure don't want to go try to rectify this poor decision 3 years post installation! Say it ain't so! 73/jeff/ac0c alpha-charlie-zero-charlie www.ac0c.com On 11/6/20 10:59 PM, donov...@erols.com wrote: Always beware of any communication that begins "with all due respect" - Original Message - From: "Wes" To: topband@contesting.com Sent: Saturday, November 7, 2020 4:49:23 AM Subject: Re: Topband: OT - Bonding Radials at Intersections With all due respect, I must ask, how many megawatts are you guys running? Wes N7WS On 11/6/2020 3:26 PM, donov...@erols.com wrote: Hi Carl, If the insulation breaks down they will arc, potentially causing a fire 73 Frank W3LPL On 11/6/2020 4:27 PM, Richard (Rick) Karlquist wrote: On 11/6/2020 1:10 PM, Carl Clawson wrote: Frank, “Must” is a strong word. What goes wrong if you cross them? 73, Carl WS7L Also, if insulated wires are used for radials that cross over each other, is that to be treated differently than bare metal wires that cross over each other and touch so as to have electrical connectivity? Does it matter if cross over radials are soldered at the crossovers, so as to prevent parasitic "diodes". For whatever weird reason, the price of insulated wire is nearly always lower than the equivalent bare wire. And Romex sells for less than the equivalent individual wires. Rick N6RK _ Searchable Archives:http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: OT - Bonding Radials at Intersections
Always beware of any communication that begins "with all due respect" - Original Message - From: "Wes" To: topband@contesting.com Sent: Saturday, November 7, 2020 4:49:23 AM Subject: Re: Topband: OT - Bonding Radials at Intersections With all due respect, I must ask, how many megawatts are you guys running? Wes N7WS On 11/6/2020 3:26 PM, donov...@erols.com wrote: > Hi Carl, > > > If the insulation breaks down they will arc, potentially causing a fire > > > 73 > Frank > W3LPL > > On 11/6/2020 4:27 PM, Richard (Rick) Karlquist wrote: >> On 11/6/2020 1:10 PM, Carl Clawson wrote: >>> Frank, >>> >>> “Must” is a strong word. What goes wrong if you cross them? >>> >>> 73, Carl WS7L >>> >> Also, if insulated wires are used for radials that cross >> over each other, is that to be treated differently than bare >> metal wires that cross over each other and touch >> so as to have electrical connectivity? >> >> Does it matter if cross over radials are soldered at the >> crossovers, so as to prevent parasitic "diodes". >> >> For whatever weird reason, the price of insulated wire is >> nearly always lower than the equivalent bare wire. And >> Romex sells for less than the equivalent individual wires. >> >> Rick N6RK >> _ >> Searchable Archives:http://www.contesting.com/_topband - Topband >> Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: OT - Bonding Radials at Intersections
With all due respect, I must ask, how many megawatts are you guys running? Wes N7WS On 11/6/2020 3:26 PM, donov...@erols.com wrote: Hi Carl, If the insulation breaks down they will arc, potentially causing a fire 73 Frank W3LPL On 11/6/2020 4:27 PM, Richard (Rick) Karlquist wrote: On 11/6/2020 1:10 PM, Carl Clawson wrote: Frank, “Must” is a strong word. What goes wrong if you cross them? 73, Carl WS7L Also, if insulated wires are used for radials that cross over each other, is that to be treated differently than bare metal wires that cross over each other and touch so as to have electrical connectivity? Does it matter if cross over radials are soldered at the crossovers, so as to prevent parasitic "diodes". For whatever weird reason, the price of insulated wire is nearly always lower than the equivalent bare wire. And Romex sells for less than the equivalent individual wires. Rick N6RK _ Searchable Archives:http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: OT - Bonding Radials at Intersections
Hi Carl, If the insulation breaks down they will arc, potentially causing a fire 73 Frank W3LPL On 11/6/2020 4:27 PM, Richard (Rick) Karlquist wrote: > > > On 11/6/2020 1:10 PM, Carl Clawson wrote: >> Frank, >> >> “Must” is a strong word. What goes wrong if you cross them? >> >> 73, Carl WS7L >> > > Also, if insulated wires are used for radials that cross > over each other, is that to be treated differently than bare > metal wires that cross over each other and touch > so as to have electrical connectivity? > > Does it matter if cross over radials are soldered at the > crossovers, so as to prevent parasitic "diodes". > > For whatever weird reason, the price of insulated wire is > nearly always lower than the equivalent bare wire. And > Romex sells for less than the equivalent individual wires. > > Rick N6RK > _ > Searchable Archives: http://www.contesting.com/_topband - Topband > Reflector -- Dave manu...@artekmanuals.com www.ArtekManuals.com -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: OT - Bonding Radials at Intersections
Among other things they will and can arc if very close or even intermittently touching. if they are not bonded the currents and voltages on each wire may be different enough to arc then you get interesting things going on especially at high power,. I had a related experience where I had radial wires stapled on a wooden fence. At one point two of the wires crossed each other, during a high power transmission the two arced repeatedly and set the fence on fire. Luckily the window of the shack faced the back yard and I saw it early on and went out an put the fire out and resolved the cause Dave NR1DX On 11/6/2020 4:27 PM, Richard (Rick) Karlquist wrote: On 11/6/2020 1:10 PM, Carl Clawson wrote: Frank, “Must” is a strong word. What goes wrong if you cross them? 73, Carl WS7L Also, if insulated wires are used for radials that cross over each other, is that to be treated differently than bare metal wires that cross over each other and touch so as to have electrical connectivity? Does it matter if cross over radials are soldered at the crossovers, so as to prevent parasitic "diodes". For whatever weird reason, the price of insulated wire is nearly always lower than the equivalent bare wire. And Romex sells for less than the equivalent individual wires. Rick N6RK _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector -- Dave manu...@artekmanuals.com www.ArtekManuals.com -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: OT - Bonding Radials at Intersections
On 11/6/2020 1:10 PM, Carl Clawson wrote: Frank, “Must” is a strong word. What goes wrong if you cross them? 73, Carl WS7L Also, if insulated wires are used for radials that cross over each other, is that to be treated differently than bare metal wires that cross over each other and touch so as to have electrical connectivity? Does it matter if cross over radials are soldered at the crossovers, so as to prevent parasitic "diodes". For whatever weird reason, the price of insulated wire is nearly always lower than the equivalent bare wire. And Romex sells for less than the equivalent individual wires. Rick N6RK _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: OT - Bonding Radials at Intersections
Frank, “Must” is a strong word. What goes wrong if you cross them? 73, Carl WS7L On Thu, Nov 5, 2020 at 9:47 PM wrote: > Hi Bob, > > > While bonding the radials is desirable, its not essential. But you > must NOT cross the radials over each other. > > > ... > 73 > Frank > W3LPL > > > > > > - Original Message - > > From: "Robert L. Chortek" > To: "TopBand List" > Sent: Friday, November 6, 2020 2:05:43 AM > Subject: Topband: OT - Bonding Radials at Intersections > > I just finished installing a two element vertical array on 40M. The > instructions say to bond the radials from one vertical where they intersect > with a radial for the other vertical. > > My question is, is this really necessary and what effect would doing so > (or not) have on the performance of the Array? > > Much appreciated. > > 73, > > Bob AA6VB > > Bob > Robert L. Chortek > _ > Searchable Archives: http://www.contesting.com/_topband - Topband > Reflector > > _ > Searchable Archives: http://www.contesting.com/_topband - Topband > Reflector > _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: OT - Bonding Radials at Intersections
I use the "Lead-Free" plumbing solder to connect my radials & ground straps. "Oatley Safe-Flo Lead Free Solder" is sold in most Home Improvement stores in the plumbing department. Do NOT use Lead-Tin "Radio Solder" - as that will leach into the soil fairly rapidly. 73 Lloyd - N9LB -Original Message- From: Topband [mailto:topband-bounces+lloydberg=tds@contesting.com] On Behalf Of Rob Atkinson Sent: Friday, November 06, 2020 4:55 AM To: topband@contesting.com Subject: Topband: OT - Bonding Radials at Intersections Scroll down to drawing 5 and 6 to see the proper way of handing intersecting radials. http://www.hatdaw.com/papers/groundsystem.pdf 73 Rob K5UJ _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: OT - Bonding Radials at Intersections
Hi Bob, While bonding the radials is desirable, its not essential. But you must NOT cross the radials over each other. The radials of a multi-element vertical array are usually bonded to a common wire bisecting the verticals where they would otherwise cross over each other. See this figure by K6LA: https://ac6la.com/adhoc/radials3.png I modelled phased vertical arrays where the radials are laid out exactly as shown by K6LA but without the bisecting wire. In this configuration the radials that would have been bonded to the bisecting wire are instead simply continued to the bottom of the adjacent vertical. The model shows absolutely no difference in the performance of a multi-element vertical array with -- or without -- the bisecting wire(s). I built my 160 meter 4-square array in this fashion -- without the bisecting wires -- and its performance is excellent. 73 Frank W3LPL - Original Message - From: "Robert L. Chortek" To: "TopBand List" Sent: Friday, November 6, 2020 2:05:43 AM Subject: Topband: OT - Bonding Radials at Intersections I just finished installing a two element vertical array on 40M. The instructions say to bond the radials from one vertical where they intersect with a radial for the other vertical. My question is, is this really necessary and what effect would doing so (or not) have on the performance of the Array? Much appreciated. 73, Bob AA6VB Bob Robert L. Chortek _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
