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New Ten-Tec antenna
Hello to all,
I have looked with interest at the new Ten-Tec Vee Beam Terminated antenna. Is there a guru on the list who has the knowlege to share on how to duplicate this antenna? It is a vee beam with each leg terminated to ground with a resistor, and there is a balun of sorts at the input. I remember an antenna similar to this years ago, and I think ten-tec will have a winner with this if folks can get away from the supposed "horror" of a terminated antenna. Details at www.tentec.com I wish I could afford it at this time!! Regards, Howard |
"Howard" wrote in message om... Hello to all, I have looked with interest at the new Ten-Tec Vee Beam Terminated antenna. Is there a guru on the list who has the knowlege to share on how to duplicate this antenna? It is a vee beam with each leg terminated to ground with a resistor, and there is a balun of sorts at the input. I remember an antenna similar to this years ago, and I think ten-tec will have a winner with this if folks can get away from the supposed "horror" of a terminated antenna. Details at www.tentec.com It's just a half-rhombic, but must suffer seriously from the poor grounding that the ground rods provide. That will both reduce the front-to-back ratio and make the input impedance vary (much) more with frequency. A real unidirectional rhombic has the single terminating resistor directly between the two sides, and needs no ground. Does this terminated V have about the same gain as a rhombic the same length? I suspect so. The rhombic would require four tall supports - a clear disadvantage. Rhombics were used at VHF years ago. The 1950s NBS (now NOAA) Cedar Rapids (IA) to Sterling (VA) and Longbranch (IL) to Boulder (CO) scatter links on 49.8 MHz (or nearby) used 600 foot long rhombics. Really strong Es allowed lighting a small lamp directly from the receiving antenna - the transmitter ran 20 kW, IIRC. |
"Howard" wrote in message om... Hello to all, I have looked with interest at the new Ten-Tec Vee Beam Terminated antenna. Is there a guru on the list who has the knowlege to share on how to duplicate this antenna? It is a vee beam with each leg terminated to ground with a resistor, and there is a balun of sorts at the input. I remember an antenna similar to this years ago, and I think ten-tec will have a winner with this if folks can get away from the supposed "horror" of a terminated antenna. Details at www.tentec.com It's just a half-rhombic, but must suffer seriously from the poor grounding that the ground rods provide. That will both reduce the front-to-back ratio and make the input impedance vary (much) more with frequency. A real unidirectional rhombic has the single terminating resistor directly between the two sides, and needs no ground. Does this terminated V have about the same gain as a rhombic the same length? I suspect so. The rhombic would require four tall supports - a clear disadvantage. Rhombics were used at VHF years ago. The 1950s NBS (now NOAA) Cedar Rapids (IA) to Sterling (VA) and Longbranch (IL) to Boulder (CO) scatter links on 49.8 MHz (or nearby) used 600 foot long rhombics. Really strong Es allowed lighting a small lamp directly from the receiving antenna - the transmitter ran 20 kW, IIRC. |
On 18 Sep 2003 08:21:43 -0700, (Howard) wrote:
Hello to all, I have looked with interest at the new Ten-Tec Vee Beam Terminated antenna. Is there a guru on the list who has the knowlege to share on how to duplicate this antenna? It is a vee beam with each leg terminated to ground with a resistor, and there is a balun of sorts at the input. I remember an antenna similar to this years ago, and I think ten-tec will have a winner with this if folks can get away from the supposed "horror" of a terminated antenna. Details at www.tentec.com I wish I could afford it at this time!! Regards, Howard Running a model with an apex angle of 90º as per the illustration on page one of their Installation and Operation manual. NEC reports the following maximum forward gain: Using 50 foot arms Freq. MHz Gain dBi Elevation Angle 3.5 -13.8 80º 7.0 -5.3 55º 14 -1.8 33º 21 5.63 23º 28 6.51 47º Using 100 foot arms 3.5 -9.4 64º 7.0 -1.06 47º 14 4.51 25º 21 4.35 17º 28 3.24 57º Danny, K6MHE |
On Thu, 18 Sep 2003 11:23:21 -0400, "R J Carpenter"
wrote: It's just a half-rhombic, but must suffer seriously from the poor grounding that the ground rods provide. That will both reduce the front-to-back ratio and make the input impedance vary (much) more with frequency. According to US Army Signal Corps FM 24-18 chapter 3 section 7, poor grounds can be helped with a dose of the following to increase conductivity (in order of conductivity) Sodium Chloride Calcium Chloride Copper Sulfate Magnesium Sulfate Postassium Nitrate Course they also say dont let it get into the drinking water grin mike |
On Thu, 18 Sep 2003 11:23:21 -0400, "R J Carpenter"
wrote: It's just a half-rhombic, but must suffer seriously from the poor grounding that the ground rods provide. That will both reduce the front-to-back ratio and make the input impedance vary (much) more with frequency. According to US Army Signal Corps FM 24-18 chapter 3 section 7, poor grounds can be helped with a dose of the following to increase conductivity (in order of conductivity) Sodium Chloride Calcium Chloride Copper Sulfate Magnesium Sulfate Postassium Nitrate Course they also say dont let it get into the drinking water grin mike |
Yeah, and I can just see the neighbours demanding you shut down your
dangerous transmitter. "Look at all the dead snails! See!! It's deadly!!!" Rob mike wrote: On Thu, 18 Sep 2003 11:23:21 -0400, "R J Carpenter" wrote: It's just a half-rhombic, but must suffer seriously from the poor grounding that the ground rods provide. That will both reduce the front-to-back ratio and make the input impedance vary (much) more with frequency. According to US Army Signal Corps FM 24-18 chapter 3 section 7, poor grounds can be helped with a dose of the following to increase conductivity (in order of conductivity) Sodium Chloride Calcium Chloride Copper Sulfate Magnesium Sulfate Postassium Nitrate Course they also say dont let it get into the drinking water grin mike |
Yeah, and I can just see the neighbours demanding you shut down your
dangerous transmitter. "Look at all the dead snails! See!! It's deadly!!!" Rob mike wrote: On Thu, 18 Sep 2003 11:23:21 -0400, "R J Carpenter" wrote: It's just a half-rhombic, but must suffer seriously from the poor grounding that the ground rods provide. That will both reduce the front-to-back ratio and make the input impedance vary (much) more with frequency. According to US Army Signal Corps FM 24-18 chapter 3 section 7, poor grounds can be helped with a dose of the following to increase conductivity (in order of conductivity) Sodium Chloride Calcium Chloride Copper Sulfate Magnesium Sulfate Postassium Nitrate Course they also say dont let it get into the drinking water grin mike |
Dan Richardson wrote in message . ..
On 18 Sep 2003 08:21:43 -0700, (Howard) wrote: Hello to all, I have looked with interest at the new Ten-Tec Vee Beam Terminated antenna. Is there a guru on the list who has the knowlege to share on how to duplicate this antenna? It is a vee beam with each leg terminated to ground with a resistor, and there is a balun of sorts at the input. I remember an antenna similar to this years ago, and I think ten-tec will have a winner with this if folks can get away from the supposed "horror" of a terminated antenna. Details at www.tentec.com I wish I could afford it at this time!! Regards, Howard Running a model with an apex angle of 90º as per the illustration on page one of their Installation and Operation manual. NEC reports the following maximum forward gain: Using 50 foot arms Freq. MHz Gain dBi Elevation Angle 3.5 -13.8 80º 7.0 -5.3 55º 14 -1.8 33º 21 5.63 23º 28 6.51 47º Using 100 foot arms 3.5 -9.4 64º 7.0 -1.06 47º 14 4.51 25º 21 4.35 17º 28 3.24 57º Danny, K6MHE Danny, can you give us a match/swr for each band? The antenna is supposed to not need matching. Brian |
Dan Richardson wrote in message . ..
On 18 Sep 2003 08:21:43 -0700, (Howard) wrote: Hello to all, I have looked with interest at the new Ten-Tec Vee Beam Terminated antenna. Is there a guru on the list who has the knowlege to share on how to duplicate this antenna? It is a vee beam with each leg terminated to ground with a resistor, and there is a balun of sorts at the input. I remember an antenna similar to this years ago, and I think ten-tec will have a winner with this if folks can get away from the supposed "horror" of a terminated antenna. Details at www.tentec.com I wish I could afford it at this time!! Regards, Howard Running a model with an apex angle of 90º as per the illustration on page one of their Installation and Operation manual. NEC reports the following maximum forward gain: Using 50 foot arms Freq. MHz Gain dBi Elevation Angle 3.5 -13.8 80º 7.0 -5.3 55º 14 -1.8 33º 21 5.63 23º 28 6.51 47º Using 100 foot arms 3.5 -9.4 64º 7.0 -1.06 47º 14 4.51 25º 21 4.35 17º 28 3.24 57º Danny, K6MHE Danny, can you give us a match/swr for each band? The antenna is supposed to not need matching. Brian |
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Dan Richardson wrote in message . ..
On 30 Sep 2003 09:11:02 -0700, (Brian) wrote: Danny, can you give us a match/swr for each band? The antenna is supposed to not need matching. Brian Brain, According to the manual the antenna uses a 50 to 800 Ohm broadband matching transformer at the feed point. Assuming then that the antenna's feed point should be near the 800-Ohm figure I ran a sweep for 3.5, 7, 10.1, 14.2 and 28.5 MHz referencing a 800-Ohm impedance to calculate the SWR. I got the following results: 3.5 1.40:1 7.0 1.88:1 10.1 1.92:1 14.2 1.96:1 21.2 2.37:1 28.5 2.41:1 Those figures appear to be in close agreement with the manufacture's claim. That said I feel that worrying about the SWR's effects on antenna operation is somewhat like worrying how well a car will run based on the amount of air pressure in the tires. 73 Danny, K6MHE Danny, thanks for running the numbers. I appreciate it. And feel free to drive your car w/o air pressure in your tires. Maybe you've got the Presedential and Armored Car series tires. Since I don't, I prefer air in my tires, and in my antennas, I prefer an SWR somewhat below my transmitter's SWR protection circuit's limit. 73, BrIan/N0IMD |
Dan Richardson wrote in message . ..
On 30 Sep 2003 09:11:02 -0700, (Brian) wrote: Danny, can you give us a match/swr for each band? The antenna is supposed to not need matching. Brian Brain, According to the manual the antenna uses a 50 to 800 Ohm broadband matching transformer at the feed point. Assuming then that the antenna's feed point should be near the 800-Ohm figure I ran a sweep for 3.5, 7, 10.1, 14.2 and 28.5 MHz referencing a 800-Ohm impedance to calculate the SWR. I got the following results: 3.5 1.40:1 7.0 1.88:1 10.1 1.92:1 14.2 1.96:1 21.2 2.37:1 28.5 2.41:1 Those figures appear to be in close agreement with the manufacture's claim. That said I feel that worrying about the SWR's effects on antenna operation is somewhat like worrying how well a car will run based on the amount of air pressure in the tires. 73 Danny, K6MHE Danny, thanks for running the numbers. I appreciate it. And feel free to drive your car w/o air pressure in your tires. Maybe you've got the Presedential and Armored Car series tires. Since I don't, I prefer air in my tires, and in my antennas, I prefer an SWR somewhat below my transmitter's SWR protection circuit's limit. 73, BrIan/N0IMD |
On 2 Oct 2003 10:24:25 -0700, (Brian) wrote:
Dan Richardson wrote in message . .. On 30 Sep 2003 09:11:02 -0700, (Brian) wrote: Danny, can you give us a match/swr for each band? The antenna is supposed to not need matching. Brian Brain, According to the manual the antenna uses a 50 to 800 Ohm broadband matching transformer at the feed point. Assuming then that the antenna's feed point should be near the 800-Ohm figure I ran a sweep for 3.5, 7, 10.1, 14.2 and 28.5 MHz referencing a 800-Ohm impedance to calculate the SWR. I got the following results: 3.5 1.40:1 7.0 1.88:1 10.1 1.92:1 14.2 1.96:1 21.2 2.37:1 28.5 2.41:1 Those figures appear to be in close agreement with the manufacture's claim. That said I feel that worrying about the SWR's effects on antenna operation is somewhat like worrying how well a car will run based on the amount of air pressure in the tires. 73 Danny, K6MHE Danny, thanks for running the numbers. I appreciate it. And feel free to drive your car w/o air pressure in your tires. Maybe you've got the Presedential and Armored Car series tires. Since I don't, I prefer air in my tires, and in my antennas, I prefer an SWR somewhat below my transmitter's SWR protection circuit's limit. 73, BrIan/N0IMD I guess I choose a poor analogy regarding SWR. On my list SWR is the least of my worries as it is one of the easiest to fix. I would be much more interested in the antenna's pattern (launching the signal in a direction and angle I wish), what amount of gain it has at that direction/angle and what efficiency it operated at. Back to the analogy of a car. I would be more interested in how the engine ran, transmission worked and so forth. A flat tire (read excessive SWR) is easy to fix but rebuilding an engine is another matter. 73 Danny |
On 2 Oct 2003 10:24:25 -0700, (Brian) wrote:
Dan Richardson wrote in message . .. On 30 Sep 2003 09:11:02 -0700, (Brian) wrote: Danny, can you give us a match/swr for each band? The antenna is supposed to not need matching. Brian Brain, According to the manual the antenna uses a 50 to 800 Ohm broadband matching transformer at the feed point. Assuming then that the antenna's feed point should be near the 800-Ohm figure I ran a sweep for 3.5, 7, 10.1, 14.2 and 28.5 MHz referencing a 800-Ohm impedance to calculate the SWR. I got the following results: 3.5 1.40:1 7.0 1.88:1 10.1 1.92:1 14.2 1.96:1 21.2 2.37:1 28.5 2.41:1 Those figures appear to be in close agreement with the manufacture's claim. That said I feel that worrying about the SWR's effects on antenna operation is somewhat like worrying how well a car will run based on the amount of air pressure in the tires. 73 Danny, K6MHE Danny, thanks for running the numbers. I appreciate it. And feel free to drive your car w/o air pressure in your tires. Maybe you've got the Presedential and Armored Car series tires. Since I don't, I prefer air in my tires, and in my antennas, I prefer an SWR somewhat below my transmitter's SWR protection circuit's limit. 73, BrIan/N0IMD I guess I choose a poor analogy regarding SWR. On my list SWR is the least of my worries as it is one of the easiest to fix. I would be much more interested in the antenna's pattern (launching the signal in a direction and angle I wish), what amount of gain it has at that direction/angle and what efficiency it operated at. Back to the analogy of a car. I would be more interested in how the engine ran, transmission worked and so forth. A flat tire (read excessive SWR) is easy to fix but rebuilding an engine is another matter. 73 Danny |
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