Re: Topband: BOG questions
Lloyd et all Isn't a BOG say 3" or 6" high draped over the weeds really now a very low beverage and not a BOG at all? It now needs to be longer and terminated to ground on the far end like you would a beverage in order to be effective? Wish the NEC4 engine wasn't so expensive I am getting the itch to spend all night modeling these permutations and combinations There are two advantages to a BOG as I see it . It is technically very easy to install if you can expose bare dirt to lay it on and it is shorter than by almost half� for useful F/B. Dave NR1DX manu...@artekmanuals.com On 8/25/2019 4:15 PM, Lloyd - N9LB wrote: Hello Mark! I did a similar thing a couple of years ago in order to run a BOG across the abandoned farm behind my property. Never doing that again! The following season I set the mower deck to maximum height on my lawn and garden tractor and drove thru the same field of six foot high weeds and thorns ( and assorted ticks ). That worked a lot better ( and much safer too ). What I learned was that the BOG works well when laying directly on the ground, but was worthless when draped over weeds. GL es 73 Lloyd - N9LB -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Mark Lunday Sent: Sunday, August 25, 2019 2:48 PM To: Mikek ; topband@contesting.com Subject: Re: Topband: BOG questions OK, my wife now is convinced that I have a screw loose in the brain somewhere (she had plenty of evidence before but decided to give me the benefit of the doubt until today)I just spent an hour in the hot North Carolina sun, wearing jeans and a heavy winter jacket so that I could wade through 300 feet of neck-high thorns and nettles and tamp those down so I could re-lay the insulated BOG wire. I do this for three reasons: 1. I want to confirm the theory that growing grass/weeds around the original installation 11 moths ago have compromised performance 2. A nearby lightning strike Friday night wiped out something in my HiZ 4-square receiving array, and I refuse to use the 160 meter inverted L for receive, even though this is a quiet QTH. 3. Even at my age of 55, I find sudden surges of energy when involved with such projects. I shall share my observations as the nights progress, while I investigate/diagnose/repair/replace the damaged parts on the HiZ array. Mark Lunday, WD4ELG Greensboro, NC FM06be wd4...@arrl.net http://wd4elg.blogspot.com SKCC #16439 FISTS #17972 QRP ARCI #16497 _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ 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
Topband: Using a Tower to Support an Inverted L
I just replaced my low 160 meter dipole with an Inverted L to improve my transmitting signal. The Inverted L is about 2 feet from a crank up tower I use on other bands. Here is the general layout: Tower height is 55 ft. On top is a 4 element WRC tri-bander and 8 feet above is a 2 element M2 shortened 40 meter yagi. The inverted L is 55 ft vertical about 2 feet from the tower, then 80 ft horizontal. Single wire (#13 copper). The radial system is buried 40 wires 100-135 ft long. After installation I got the following readings at the base of the antenna: SWR increases from 1.2 to 1.6 (1.800 - 2.000 Mhtz) Measured "Resistance" was 52-77 ohms; Reactance 7-18 ohms (using MFJ 259B) There is obvious interaction between the "L" and the Tower/Yagis. Has anyone had experience with or modeled such a setup? I am really curious as to what I can expect from this setup. Thanks for any help you can provide. Udo NI0G _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: BOG questions
Hello Mark! I did a similar thing a couple of years ago in order to run a BOG across the abandoned farm behind my property. Never doing that again! The following season I set the mower deck to maximum height on my lawn and garden tractor and drove thru the same field of six foot high weeds and thorns ( and assorted ticks ). That worked a lot better ( and much safer too ). What I learned was that the BOG works well when laying directly on the ground, but was worthless when draped over weeds. GL es 73 Lloyd - N9LB -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Mark Lunday Sent: Sunday, August 25, 2019 2:48 PM To: Mikek ; topband@contesting.com Subject: Re: Topband: BOG questions OK, my wife now is convinced that I have a screw loose in the brain somewhere (she had plenty of evidence before but decided to give me the benefit of the doubt until today)I just spent an hour in the hot North Carolina sun, wearing jeans and a heavy winter jacket so that I could wade through 300 feet of neck-high thorns and nettles and tamp those down so I could re-lay the insulated BOG wire. I do this for three reasons: 1. I want to confirm the theory that growing grass/weeds around the original installation 11 moths ago have compromised performance 2. A nearby lightning strike Friday night wiped out something in my HiZ 4-square receiving array, and I refuse to use the 160 meter inverted L for receive, even though this is a quiet QTH. 3. Even at my age of 55, I find sudden surges of energy when involved with such projects. I shall share my observations as the nights progress, while I investigate/diagnose/repair/replace the damaged parts on the HiZ array. Mark Lunday, WD4ELG Greensboro, NC FM06be wd4...@arrl.net http://wd4elg.blogspot.com SKCC #16439 FISTS #17972 QRP ARCI #16497 _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: BOG questions
OK, my wife now is convinced that I have a screw loose in the brain somewhere (she had plenty of evidence before but decided to give me the benefit of the doubt until today)I just spent an hour in the hot North Carolina sun, wearing jeans and a heavy winter jacket so that I could wade through 300 feet of neck-high thorns and nettles and tamp those down so I could re-lay the insulated BOG wire. I do this for three reasons: 1. I want to confirm the theory that growing grass/weeds around the original installation 11 moths ago have compromised performance 2. A nearby lightning strike Friday night wiped out something in my HiZ 4-square receiving array, and I refuse to use the 160 meter inverted L for receive, even though this is a quiet QTH. 3. Even at my age of 55, I find sudden surges of energy when involved with such projects. I shall share my observations as the nights progress, while I investigate/diagnose/repair/replace the damaged parts on the HiZ array. Mark Lunday, WD4ELG Greensboro, NC FM06be wd4...@arrl.net http://wd4elg.blogspot.com SKCC #16439 FISTS #17972 QRP ARCI #16497 _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: An oddball question about a BOG.
The comments in your first paragraph are very confusing, mixing up information on different antennas, old or proposed, and parts data, without clearly distinguishing what each comment refers to. I doubt that anyone will be able to sort that out unless they went thru the thread on QRZ. https://forums.qrz.com/index.php?threads/feedback-on-building-a-bog-antenna.669192/ Take a little more care in describing things so that you don't mislead people. There are some knowledgeable people on this forum, and I would like to hear what they have to say. The main problem with your first attempt was that the beads you added had little inductance and a lot of resistance, a total of 238 ohms on 1 MHz and 895 ohms on 4 MHz. That pretty much kills the antenna. Although I am skeptical of NEC's ability to accurately model a long BOG, a 250 foot BOG on 500 kHz isn't a long antenna. I think NEC data should be usable for that, although performance of a BOG can vary a lot in actual implementation because of variations in ground characteristics and actual height above the dirt. Performance of low gain antennas are also very sensitive to circuit implementation and taking care of common mode current. And don't point them at noise sources. 500 kHz to 4 MHz is an ambitious goal for a 250 ft long BOG. W8JI's discussion on adding beads and inductors to Beverages is very good, but I don't think you will have to worry about a 250 ft BOG reversing directions on 500 kHz because you added too much inductance. You will be worrying more about getting enough inductance to produce some front to back in the pattern. And of course the required inductance will vary with frequency, so you have to figure out how to do that if you want it to cover a wide bandwidth. Jerry, K4SAV On 8/25/2019 12:31 PM, Mikek wrote: I have never modelled an inductively-loaded Beverage, but my intuition is that it will not perform any better than an unloaded wire of the same physical length. I haven't modeled for 10 years and even then I was in the dark. I started on this quest when I saw this W8JI page about inductively loaded beverages, I thought why can't that work on a BOG. http://www.w8ji.com/slinky_and_loaded_beverages.htm There is discussion about having to much inductance which causes a reversal of the receive direction. I also have some idea that the BOG already has a slowed VF because it is on the ground. So I don't how much more inductance we could add. On a forum, someone modeled my first BOG that I used #73 binocular cores on, using one pass through one hole. This was about 1/2 of the suggested value that the model showed at 1MHz. Also the cores had a Q of less than 2! It was suggested that the losses did more for the pattern than the inductance. The modeler also said that you need 70uH at 500kHz. The modeler did say the inductors altered the pattern to some degree (I don't think he was impressed), He said, "At 1 MHz, front to back at 20 degrees elevation improves by 1.5 dB and gain drops by 6.6. dB. Elevation beamwidth drops by 9.6 degrees." *However, *those numbers were with the values *I* used, they were not optimized values. I have no idea how much iteration the modeler did, I'm thinking not a lot, he didn't concentrate on just my BOG, but I don't know that for sure. It needs to be modeled. In the model. I don't know if it would best to optimize the length for 4MHz and then load and terminate for best 550kHz or, just make it as long as I can, 250ft in my case and go from there. It may be a compromise in my case.(550kHz to 4MHz) For you guys wanting 160M and as side benefit 80M, you might be able to optimize on 80M and then load it for 160M and still get good results. In the model as frequency goes down the size of the inductors must increase to optimize, I expect the termination resistance also would change. I envision two knobs, one adjusts termination value and one alters the inductance of the nine inductors. Probably some interaction, so just adjust them until you have the best S/N. Inductance may have a narrow range so you could mark your adjustment on the scale for the frequency of interest. I'd love some response to this, but if you don't have any, can you help me with this. How do you respond to a specific post? I'm just clicking topband@contesting.com and then copy and pasting in what I want. Is that the way it is done here? I'm used to forums and newsgroups where you can quote at the push of a button. Thanks, Mike _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: An oddball question about a BOG.
I have never modelled an inductively-loaded Beverage, but my intuition is that it will not perform any better than an unloaded wire of the same physical length. I haven't modeled for 10 years and even then I was in the dark. I started on this quest when I saw this W8JI page about inductively loaded beverages, I thought why can't that work on a BOG. http://www.w8ji.com/slinky_and_loaded_beverages.htm There is discussion about having to much inductance which causes a reversal of the receive direction. I also have some idea that the BOG already has a slowed VF because it is on the ground. So I don't how much more inductance we could add. On a forum, someone modeled my first BOG that I used #73 binocular cores on, using one pass through one hole. This was about 1/2 of the suggested value that the model showed at 1MHz. Also the cores had a Q of less than 2! It was suggested that the losses did more for the pattern than the inductance. The modeler also said that you need 70uH at 500kHz. The modeler did say the inductors altered the pattern to some degree (I don't think he was impressed), He said, "At 1 MHz, front to back at 20 degrees elevation improves by 1.5 dB and gain drops by 6.6. dB. Elevation beamwidth drops by 9.6 degrees." *However, *those numbers were with the values *I* used, they were not optimized values. I have no idea how much iteration the modeler did, I'm thinking not a lot, he didn't concentrate on just my BOG, but I don't know that for sure. It needs to be modeled. In the model. I don't know if it would best to optimize the length for 4MHz and then load and terminate for best 550kHz or, just make it as long as I can, 250ft in my case and go from there. It may be a compromise in my case.(550kHz to 4MHz) For you guys wanting 160M and as side benefit 80M, you might be able to optimize on 80M and then load it for 160M and still get good results. In the model as frequency goes down the size of the inductors must increase to optimize, I expect the termination resistance also would change. I envision two knobs, one adjusts termination value and one alters the inductance of the nine inductors. Probably some interaction, so just adjust them until you have the best S/N. Inductance may have a narrow range so you could mark your adjustment on the scale for the frequency of interest. I'd love some response to this, but if you don't have any, can you help me with this. How do you respond to a specific post? I'm just clicking topband@contesting.com and then copy and pasting in what I want. Is that the way it is done here? I'm used to forums and newsgroups where you can quote at the push of a button. Thanks, Mike _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: Modeling close to earth ( was Odd-ball question)
Not enough coffee earlier a better description of the radials: three 90ft radials radials 7'ft high spaced in 120 degree increments (0, 120and 240 degrees) Another interesting side notes discovered while doing the modeling 1) A three radial version in a 180 degree half circle (0, 90 and 180) or what I like to call the "up against the fence", resulted in very much the same modeled impedance and only slight pattern distortion ( less than 1db) , Predicted radiated field strength by adding the forth radial at 270 degrees only resulted in an increase in signal in that direction a few tenths of a dB 2) Inverted L's pattern distortion can be non trivial depending on the length of the top section. The signal decreases in the direction the top section "points". In the past I had a preference for having very long top sections ( Total length: vertical + horizontal on the order of 150') so as to increase the real portion of feed point impedance to 50ohms and then tune out the increased reactive portion with a series cap. Depending on how long the top section is signals in the direction of the pointing top of the L can be down by as much as 3 to 6dB !!. At the new QTH the best tree supports resulted in a 6db pattern decrease directly pointed a Europe 8^(... Which is why I ended up with a "T" instead of an "L".) Dave NR1DX On 8/25/2019 8:25 AM, Artek Manuals wrote: Jerry et all My personal antenna FOR 160 was/is as follows 160M T: 60' Tall with with a 78' flattop. The "bottom" is at 7' ( so the actual vertical element is 53') with three 90' radials at 7' spaced pretty nearly in 60 degree increments ( 60, 120, 240). There is a tapped inductor in series with the ground side (NOT the vertical side) of the feed point used to resonate the whole thing . For the general approach to loading and using non-resonant radials I was strongly influenced by K5IU's work in Spring 1997 Communications Quarterly (google should find you reprints of that) . The vertical is #14 bare stranded copper and the radials are #10 Bare solid copper ( no magic on sizes etc just what I happened to have on hand. Ezenec says this should be around 13 ohms at 1840 resonance ( with a 23uh series inductor) . In practice it is closer to 25ohms at resonance with a about 17uh of inductance. It is then matched with a 2:1 UNUN to 50 ohms. This antenna REALLY NEEDS and uses a common mode choke at the feed point . This turned out to 10 to be ten FT-240-43 torroid's with 4 turns of coax through the batch, lesser amounts of ferrite became quite hot. After the smoke clears it all appears to work very well I have worked 24 countries on 5 continents ( still need Antarctica and Asia...tough on any band from FL) in just 4 SUMMER months and I am sure that total will climb quickly once the winter season starts. For the FT8 doom and gloomers half of these were on CW8^) Happy to share details of the 80 and 40 M antennas off list, not relevant to the topband list ! Dave NR1Dx manu...@artekmanuals.com On 8/25/2019 1:33 AM, K4SAV wrote: Dave Just a clarification. I didn't want your actual data. All I wanted was the length of the wires and the frequency. Jerry On 8/24/2019 9:30 PM, K4SAV wrote: Hey Dave I'm interested in your data. How long were the radials and what frequency were you using for the measurements. I suspect that NEC2 may be close enough to be generally useful (accuracy is questionable) for a BOG up to 250 ft on 160. My measurements (several of them) say that NEC isn't close for a 350 ft BOG. Usually my BOGs are 1 to 2 inches above the dirt because they sit on dead grass. I seriously doubt that NEC4 will be accurate for a 350 ft BOG either. I have seen a 450 ft BOG pattern generated by NEC4 and I can duplicate it with NEC2, (with only minor insignificant squiggle differences) and I know that NEC2 is wrong. I suspect that as frequency decreases or the wire becomes shorter, NEC answers will improve. A data point from someone else would be nice to know. Jerry, K4SAV On 8/24/2019 7:53 PM, Artek Manuals wrote: Chuck et all It is well documented that the the NEC-2 based programs leave something to be desired� with wires on or very near the ground, This includes most of the EZENEC� family and MMANA-G� Purportedly NEC-4 ( there is a Ezenec version which runs with NEC 4 engine ... not a cheap date) does deal with the near earth problem . How close is "Close" is a matter of conjecture. A friend of mine and I have been working on building and modeling vertical antennas ( Verticals, Inv-L and T's) for 160/80/40 with ELEVATED NON-RESONANT radials at 3' and 6' (google "K5IU Elevated Radials") . The good news is at 3' and above both NEC 2 and NEC 4 models agree within 5% or better.� We have not done any comparisons below 3' Dave NR1DX On 8/24/2019 1:41 PM, Chuck Dietz wrote: I seem to remember someone saying the modelling programs are unreliable when a w
Re: Topband: Modeling close to earth ( was Odd-ball question)
Jerry et all My personal antenna FOR 160 was/is as follows 160M T: 60' Tall with with a 78' flattop. The "bottom" is at 7' ( so the actual vertical element is 53') with three 90' radials at 7' spaced pretty nearly in 60 degree increments ( 60, 120, 240). There is a tapped inductor in series with the ground side (NOT the vertical side) of the feed point used to resonate the whole thing . For the general approach to loading and using non-resonant radials I was strongly influenced by K5IU's work in Spring 1997 Communications Quarterly (google should find you reprints of that) . The vertical is #14 bare stranded copper and the radials are #10 Bare solid copper ( no magic on sizes etc just what I happened to have on hand. Ezenec says this should be around 13 ohms at 1840 resonance ( with a 23uh series inductor) . In practice it is closer to 25ohms at resonance with a about 17uh of inductance. It is then matched with a 2:1 UNUN to 50 ohms. This antenna REALLY NEEDS and uses a common mode choke at the feed point . This turned out to 10 to be ten FT-240-43 torroid's with 4 turns of coax through the batch, lesser amounts of ferrite became quite hot. After the smoke clears it all appears to work very well I have worked 24 countries on 5 continents ( still need Antarctica and Asia...tough on any band from FL) in just 4 SUMMER months and I am sure that total will climb quickly once the winter season starts. For the FT8 doom and gloomers half of these were on CW8^) Happy to share details of the 80 and 40 M antennas off list, not relevant to the topband list ! Dave NR1Dx manu...@artekmanuals.com On 8/25/2019 1:33 AM, K4SAV wrote: Dave Just a clarification. I didn't want your actual data. All I wanted was the length of the wires and the frequency. Jerry On 8/24/2019 9:30 PM, K4SAV wrote: Hey Dave I'm interested in your data. How long were the radials and what frequency were you using for the measurements. I suspect that NEC2 may be close enough to be generally useful (accuracy is questionable) for a BOG up to 250 ft on 160. My measurements (several of them) say that NEC isn't close for a 350 ft BOG. Usually my BOGs are 1 to 2 inches above the dirt because they sit on dead grass. I seriously doubt that NEC4 will be accurate for a 350 ft BOG either. I have seen a 450 ft BOG pattern generated by NEC4 and I can duplicate it with NEC2, (with only minor insignificant squiggle differences) and I know that NEC2 is wrong. I suspect that as frequency decreases or the wire becomes shorter, NEC answers will improve. A data point from someone else would be nice to know. Jerry, K4SAV On 8/24/2019 7:53 PM, Artek Manuals wrote: Chuck et all It is well documented that the the NEC-2 based programs leave something to be desired� with wires on or very near the ground, This includes most of the EZENEC� family and MMANA-G� Purportedly NEC-4 ( there is a Ezenec version which runs with NEC 4 engine ... not a cheap date) does deal with the near earth problem . How close is "Close" is a matter of conjecture. A friend of mine and I have been working on building and modeling vertical antennas ( Verticals, Inv-L and T's) for 160/80/40 with ELEVATED NON-RESONANT radials at 3' and 6' (google "K5IU Elevated Radials") . The good news is at 3' and above both NEC 2 and NEC 4 models agree within 5% or better.� We have not done any comparisons below 3' Dave NR1DX On 8/24/2019 1:41 PM, Chuck Dietz wrote: I seem to remember someone saying the modelling programs are unreliable when a wire is close to the ground. Also, there is really no way to model the properties of "ground." It can vary in just a few feet and the moisture content varies from day to day. I think this is a "try it" kind of antenna. Read other's reported results. Chuck W5PR -- 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
