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On Aug 31, 4:15 am, RHF wrote:
QUESTION FOR ONE AND ALL : Coax Cable - What's Between Your Antenna and Radio ?http://groups.yahoo.com/group/Shortw.../message/14610 Low Loss type Coax Cable ? RG58 Coax Cable ? RG8 Coax Cable? RG6 Quad-Shield Coax Cable ? WHY - Cost ? Performance ? Value ? hope this helps - iane ~ RHF . . . . At the risk of starting yet another pointless flame war, I have tried many different types of coax over the decades. And unless one is close enough to a transmitter so that any coax leakage is an issue, it simply DOES NOT MATTER. Caps for emphasis. Transfer Impedance, do a group search for my prior comments, may be a cause of concern to a very small number of radio listeners. Most noise either comes from within the home and reaches the antenna via common mode conduction up the outside of the braid and is coupled to the antenna where it becomes a noise source, or comes from "nearby" sources and reaches the antenna directly. "50" or "72" ohm coax might matter IF our receivers presented anything like a constant impedance across the bands. With very few notable exceptions, receivers have anything but a 50 Ohm impedance at more then a few chance spots. Most receivers have significantly higher imput impedances so one might argue that a higher impedance coax should be used. I have used "50", "72" and "93" coax cable with no discernable difference between either 50 or 72. 93 ohm coax works but is a PITA to put fittings on. I my home was destroyed and all my stocks of coax were destroyed, and I no longer worked where I can get 100 foot runs of good Belden coax from the trash, I would go with quad sheild Belden from one of the big Home Cheapo stores. In a pinch I would use any high quality quad shield coax such as is sold for DBS. I would strip back the jacket to insure that all 4 layers were neat and tight. I haven't checked, so I don't know what type "F" fittings and strippers/crimpers they sell. The "F" fitting can be a very good connector up into the GHz range IF good connectors and tools are used, and care is taken to install them correctly. I have been able to introduce a signal through the coax shield, but the conditions are very unlikley to occur in the wild. A 10' wire is positioned 1" from the test coax. The coax is terminated with the correct load with a properly installed connector. Then I run 10mW through a set of of 4 16:1 transformers to give a final step down 64:1. Then and only then can I receive the test signal at 1MHz. I had 300' of coax between the test jig an my receiver. And the recovered signal was low enough that when I connect a 30' piece of wire to a another section of 300' coax the noise from the real world swamped my noise source. Perhaps is you lived in Grayland or some other extremely RF quiet location TI might be an issue. And perhaps, just perhaps in such a mythical location you could detect any difference between 50 and 72 ohm coax. I tend to put "" around 50 and 72 because there are coaxes listed as 50 or 72 that might be a little off. Do not use Rat Shack, You got questions and we haven't a clue, coax. Aside from the marginal braid coverage it is also often not wound symmetrical and the outer jacket tends to crack in a very few years. For a friend we use RG174, small mini coax, that wouldn't have been my first choice, but because she lives in a home on the historic registry she didn't want to drill any holes through the thick wall, and because the home gets more then it's share of visitors interested in such historic places she wanted her antenna to keep a very low profile. There was a very small hole just large enough for the RF174 to pass through. We used white RG174 and you have to know where to look and get real close, bring a long ladder!, to find it. Not my favorite installation but it works very well. The bird feeder in the back yard doubles as a Lankford "15' relay tuned antenna". She lives out in the country, with no nearby MW stations and has fantastic reception. We ran about 50' or RG174 then at the soil line converted it to quad shielded direct burial 100' 75 ohm Belden. And we didn't bother with any matching. For any transmitter operations this is a big no no. And for anyone using a true dipole, cut for one band and not used harmonically, and if a proper balun is used, and if the dipole is at least 1/4 wavelength in height, proper (IE 72 ohm) coax it might just matter. From years of messing with feedlines I must say might because when putting up some dipoles for dedicated single frequency reception, think WWV, I could not tell any difference. Terry |
#2
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On Aug 31, 7:17 pm, RHF wrote:
On Aug 31, 6:18 am, wrote: On Aug 31, 4:15 am, RHF wrote: QUESTION FOR ONE AND ALL : Coax Cable - What's Between Your Antenna and Radio ?http://groups.yahoo.com/group/Shortw.../message/14610 Low Loss type Coax Cable ? RG58 Coax Cable ? RG8 Coax Cable? RG6 Quad-Shield Coax Cable ? WHY - Cost ? Performance ? Value ? hope this helps - iane ~ RHF . . . . At the risk of starting yet another pointless flame war, I have tried many different types of coax over the decades. And unless one is close enough to a transmitter so that any coax leakage is an issue, it simply DOES NOT MATTER. Caps for emphasis. Transfer Impedance, do a group search for my prior comments, may be a cause of concern to a very small number of radio listeners. Most noise either comes from within the home and reaches the antenna via common mode conduction up the outside of the braid and is coupled to the antenna where it becomes a noise source, or comes from "nearby" sources and reaches the antenna directly. "50" or "72" ohm coax might matter IF our receivers presented anything like a constant impedance across the bands. With very few notable exceptions, receivers have anything but a 50 Ohm impedance at more then a few chance spots. Most receivers have significantly higher imput impedances so one might argue that a higher impedance coax should be used. I have used "50", "72" and "93" coax cable with no discernable difference between either 50 or 72. 93 ohm coax works but is a PITA to put fittings on. I my home was destroyed and all my stocks of coax were destroyed, and I no longer worked where I can get 100 foot runs of good Belden coax from the trash, I would go with quad sheild Belden from one of the big Home Cheapo stores. In a pinch I would use any high quality quad shield coax such as is sold for DBS. I would strip back the jacket to insure that all 4 layers were neat and tight. I haven't checked, so I don't know what type "F" fittings and strippers/crimpers they sell. The "F" fitting can be a very good connector up into the GHz range IF good connectors and tools are used, and care is taken to install them correctly. I have been able to introduce a signal through the coax shield, but the conditions are very unlikley to occur in the wild. A 10' wire is positioned 1" from the test coax. The coax is terminated with the correct load with a properly installed connector. Then I run 10mW through a set of of 4 16:1 transformers to give a final step down 64:1. Then and only then can I receive the test signal at 1MHz. I had 300' of coax between the test jig an my receiver. And the recovered signal was low enough that when I connect a 30' piece of wire to a another section of 300' coax the noise from the real world swamped my noise source. Perhaps is you lived in Grayland or some other extremely RF quiet location TI might be an issue. And perhaps, just perhaps in such a mythical location you could detect any difference between 50 and 72 ohm coax. I tend to put "" around 50 and 72 because there are coaxes listed as 50 or 72 that might be a little off. Do not use Rat Shack, You got questions and we haven't a clue, coax. Aside from the marginal braid coverage it is also often not wound symmetrical and the outer jacket tends to crack in a very few years. For a friend we use RG174, small mini coax, that wouldn't have been my first choice, but because she lives in a home on the historic registry she didn't want to drill any holes through the thick wall, and because the home gets more then it's share of visitors interested in such historic places she wanted her antenna to keep a very low profile. There was a very small hole just large enough for the RF174 to pass through. We used white RG174 and you have to know where to look and get real close, bring a long ladder!, to find it. Not my favorite installation but it works very well. The bird feeder in the back yard doubles as a Lankford "15' relay tuned antenna". She lives out in the country, with no nearby MW stations and has fantastic reception. We ran about 50' or RG174 then at the soil line converted it to quad shielded direct burial 100' 75 ohm Belden. And we didn't bother with any matching. For any transmitter operations this is a big no no. And for anyone using a true dipole, cut for one band and not used harmonically, and if a proper balun is used, and if the dipole is at least 1/4 wavelength in height, proper (IE 72 ohm) coax it might just matter. From years of messing with feedlines I must say might because when putting up some dipoles for dedicated single frequency reception, think WWV, I could not tell any difference. Terry- Hide quoted text - - Show quoted text - Terry - I thought that you were a big proponent of Balance feed-in-lines like 300 Ohm Twin-Lead and 450 Ohm Ladder-Line. ~ RHF . For many applications I have found balanced to be easier to cleanup from a common mode perspective then coax. But since this was a thread regarding Coax I limited my comments to Coax. Balanced has strong points. But it also is twitchy in some situations. And it is a PITA to run through a bulkhead, provide acceptable (to me) "EMP" clamps, and it must be kept well away from other conductors. In situations were you have to run feedlines adjacent to other conductors, balanced may be a bad choice. Every antenna installation is different and each site needs to be evaluated and a "plan" developed for that site. Yea, sure I sit down and design every step months before I implement. For me, other then the few commercial, IE money making, projects I have designed and built, most systems grow like a weed from something simple to something more complex. And like your garden you have to trim it up every now and then to keep it working. I used a ~100 wire on and off for 40 years. Only in the last few years have I abandoned wire antennas for active and tuned verticals. But back to coax, buy good stuff, direct burial, and invest in GOOD connectors and GOOD tools. DO NOT attempt to install "F" fittings with some pliers. Good connectors and good tools will allow you to make weather tight "F" connections that will last years. Maybe decades. Done wrong "F" fittings are dead at installation or randomly soon there after. All of my receivers use BNC, OK, my DX398 is 3.5mm but the patch goes to BNC. I use a surplus video patch panel that will pass RF up to the GPS range well enough to allow my shack GPS to stay locked. I really want to make sure my home isn't moving. It really gives a 1PPS signal to drive my ZULU/EST(EDT) clock. I do convert all my balanced back to coax at the entry bulk head. As my antenna designs change, my feedlines change to match. Balanced is always worth a try. Cheap and easy. Terry |
#3
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On Aug 31, 5:31 pm, wrote:
On Aug 31, 7:17 pm, RHF wrote: On Aug 31, 6:18 am, wrote: On Aug 31, 4:15 am, RHF wrote: QUESTION FOR ONE AND ALL : Coax Cable - What's Between Your Antenna and Radio ?http://groups.yahoo.com/group/Shortw.../message/14610 Low Loss type Coax Cable ? RG58 Coax Cable ? RG8 Coax Cable? RG6 Quad-Shield Coax Cable ? WHY - Cost ? Performance ? Value ? hope this helps - iane ~ RHF . . . . At the risk of starting yet another pointless flame war, I have tried many different types of coax over the decades. And unless one is close enough to a transmitter so that any coax leakage is an issue, it simply DOES NOT MATTER. Caps for emphasis. Transfer Impedance, do a group search for my prior comments, may be a cause of concern to a very small number of radio listeners. Most noise either comes from within the home and reaches the antenna via common mode conduction up the outside of the braid and is coupled to the antenna where it becomes a noise source, or comes from "nearby" sources and reaches the antenna directly. "50" or "72" ohm coax might matter IF our receivers presented anything like a constant impedance across the bands. With very few notable exceptions, receivers have anything but a 50 Ohm impedance at more then a few chance spots. Most receivers have significantly higher imput impedances so one might argue that a higher impedance coax should be used. I have used "50", "72" and "93" coax cable with no discernable difference between either 50 or 72. 93 ohm coax works but is a PITA to put fittings on. I my home was destroyed and all my stocks of coax were destroyed, and I no longer worked where I can get 100 foot runs of good Belden coax from the trash, I would go with quad sheild Belden from one of the big Home Cheapo stores. In a pinch I would use any high quality quad shield coax such as is sold for DBS. I would strip back the jacket to insure that all 4 layers were neat and tight. I haven't checked, so I don't know what type "F" fittings and strippers/crimpers they sell. The "F" fitting can be a very good connector up into the GHz range IF good connectors and tools are used, and care is taken to install them correctly. I have been able to introduce a signal through the coax shield, but the conditions are very unlikley to occur in the wild. A 10' wire is positioned 1" from the test coax. The coax is terminated with the correct load with a properly installed connector. Then I run 10mW through a set of of 4 16:1 transformers to give a final step down 64:1. Then and only then can I receive the test signal at 1MHz. I had 300' of coax between the test jig an my receiver. And the recovered signal was low enough that when I connect a 30' piece of wire to a another section of 300' coax the noise from the real world swamped my noise source. Perhaps is you lived in Grayland or some other extremely RF quiet location TI might be an issue. And perhaps, just perhaps in such a mythical location you could detect any difference between 50 and 72 ohm coax. I tend to put "" around 50 and 72 because there are coaxes listed as 50 or 72 that might be a little off. Do not use Rat Shack, You got questions and we haven't a clue, coax. Aside from the marginal braid coverage it is also often not wound symmetrical and the outer jacket tends to crack in a very few years. For a friend we use RG174, small mini coax, that wouldn't have been my first choice, but because she lives in a home on the historic registry she didn't want to drill any holes through the thick wall, and because the home gets more then it's share of visitors interested in such historic places she wanted her antenna to keep a very low profile. There was a very small hole just large enough for the RF174 to pass through. We used white RG174 and you have to know where to look and get real close, bring a long ladder!, to find it. Not my favorite installation but it works very well. The bird feeder in the back yard doubles as a Lankford "15' relay tuned antenna". She lives out in the country, with no nearby MW stations and has fantastic reception. We ran about 50' or RG174 then at the soil line converted it to quad shielded direct burial 100' 75 ohm Belden. And we didn't bother with any matching. For any transmitter operations this is a big no no. And for anyone using a true dipole, cut for one band and not used harmonically, and if a proper balun is used, and if the dipole is at least 1/4 wavelength in height, proper (IE 72 ohm) coax it might just matter. From years of messing with feedlines I must say might because when putting up some dipoles for dedicated single frequency reception, think WWV, I could not tell any difference. Terry- Hide quoted text - - Show quoted text - Terry - I thought that you were a big proponent of Balance feed-in-lines like 300 Ohm Twin-Lead and 450 Ohm Ladder-Line. ~ RHF . For many applications I have found balanced to be easier to cleanup from a common mode perspective then coax. But since this was a thread regarding Coax I limited my comments to Coax. Balanced has strong points. But it also is twitchy in some situations. And it is a PITA to run through a bulkhead, provide acceptable (to me) "EMP" clamps, and it must be kept well away from other conductors. In situations were you have to run feedlines adjacent to other conductors, balanced may be a bad choice. Every antenna installation is different and each site needs to be evaluated and a "plan" developed for that site. Yea, sure I sit down and design every step months before I implement. For me, other then the few commercial, IE money making, projects I have designed and built, most systems grow like a weed from something simple to something more complex. And like your garden you have to trim it up every now and then to keep it working. I used a ~100 wire on and off for 40 years. Only in the last few years have I abandoned wire antennas for active and tuned verticals. But back to coax, buy good stuff, direct burial, and invest in GOOD connectors and GOOD tools. DO NOT attempt to install "F" fittings with some pliers. Good connectors and good tools will allow you to make weather tight "F" connections that will last years. Maybe decades. Done wrong "F" fittings are dead at installation or randomly soon there after. All of my receivers use BNC, OK, my DX398 is 3.5mm but the patch goes to BNC. I use a surplus video patch panel that will pass RF up to the GPS range well enough to allow my shack GPS to stay locked. I really want to make sure my home isn't moving. It really gives a 1PPS signal to drive my ZULU/EST(EDT) clock. I do convert all my balanced back to coax at the entry bulk head. As my antenna designs change, my feedlines change to match. Balanced is always worth a try. Cheap and easy. Terry- Hide quoted text - - Show quoted text - Terry, Which Type / Types of Balanced Feed-in-Lines Do You Use : {Why?} Ready Made 300 Ohm Twin Lead ? Ready Made 450 Ohm Ladder-Line ? Standard Zip-Cord {72 Ohms} ? Standard Speaker Wire {72 Ohms} ? i want to know -cause- iane ~ RHF |
#4
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On Aug 31, 6:51 pm, wrote:
On Sep 1, 1:43 am, RHF wrote: On Aug 31, 5:31 pm, wrote: On Aug 31, 7:17 pm, RHF wrote: On Aug 31, 6:18 am, wrote: On Aug 31, 4:15 am, RHF wrote: QUESTION FOR ONE AND ALL : Coax Cable - What's Between Your Antenna and Radio ?http://groups.yahoo.com/group/Shortw.../message/14610 Low Loss type Coax Cable ? RG58 Coax Cable ? RG8 Coax Cable? RG6 Quad-Shield Coax Cable ? WHY - Cost ? Performance ? Value ? hope this helps - iane ~ RHF . . . . At the risk of starting yet another pointless flame war, I have tried many different types of coax over the decades. And unless one is close enough to a transmitter so that any coax leakage is an issue, it simply DOES NOT MATTER. Caps for emphasis. Transfer Impedance, do a group search for my prior comments, may be a cause of concern to a very small number of radio listeners. Most noise either comes from within the home and reaches the antenna via common mode conduction up the outside of the braid and is coupled to the antenna where it becomes a noise source, or comes from "nearby" sources and reaches the antenna directly. "50" or "72" ohm coax might matter IF our receivers presented anything like a constant impedance across the bands. With very few notable exceptions, receivers have anything but a 50 Ohm impedance at more then a few chance spots. Most receivers have significantly higher imput impedances so one might argue that a higher impedance coax should be used. I have used "50", "72" and "93" coax cable with no discernable difference between either 50 or 72. 93 ohm coax works but is a PITA to put fittings on. I my home was destroyed and all my stocks of coax were destroyed, and I no longer worked where I can get 100 foot runs of good Belden coax from the trash, I would go with quad sheild Belden from one of the big Home Cheapo stores. In a pinch I would use any high quality quad shield coax such as is sold for DBS. I would strip back the jacket to insure that all 4 layers were neat and tight. I haven't checked, so I don't know what type "F" fittings and strippers/crimpers they sell. The "F" fitting can be a very good connector up into the GHz range IF good connectors and tools are used, and care is taken to install them correctly. I have been able to introduce a signal through the coax shield, but the conditions are very unlikley to occur in the wild. A 10' wire is positioned 1" from the test coax. The coax is terminated with the correct load with a properly installed connector. Then I run 10mW through a set of of 4 16:1 transformers to give a final step down 64:1. Then and only then can I receive the test signal at 1MHz. I had 300' of coax between the test jig an my receiver. And the recovered signal was low enough that when I connect a 30' piece of wire to a another section of 300' coax the noise from the real world swamped my noise source. Perhaps is you lived in Grayland or some other extremely RF quiet location TI might be an issue. And perhaps, just perhaps in such a mythical location you could detect any difference between 50 and 72 ohm coax. I tend to put "" around 50 and 72 because there are coaxes listed as 50 or 72 that might be a little off. Do not use Rat Shack, You got questions and we haven't a clue, coax. Aside from the marginal braid coverage it is also often not wound symmetrical and the outer jacket tends to crack in a very few years. For a friend we use RG174, small mini coax, that wouldn't have been my first choice, but because she lives in a home on the historic registry she didn't want to drill any holes through the thick wall, and because the home gets more then it's share of visitors interested in such historic places she wanted her antenna to keep a very low profile. There was a very small hole just large enough for the RF174 to pass through. We used white RG174 and you have to know where to look and get real close, bring a long ladder!, to find it. Not my favorite installation but it works very well. The bird feeder in the back yard doubles as a Lankford "15' relay tuned antenna". She lives out in the country, with no nearby MW stations and has fantastic reception. We ran about 50' or RG174 then at the soil line converted it to quad shielded direct burial 100' 75 ohm Belden. And we didn't bother with any matching. For any transmitter operations this is a big no no. And for anyone using a true dipole, cut for one band and not used harmonically, and if a proper balun is used, and if the dipole is at least 1/4 wavelength in height, proper (IE 72 ohm) coax it might just matter. From years of messing with feedlines I must say might because when putting up some dipoles for dedicated single frequency reception, think WWV, I could not tell any difference. Terry- Hide quoted text - - Show quoted text - Terry - I thought that you were a big proponent of Balance feed-in-lines like 300 Ohm Twin-Lead and 450 Ohm Ladder-Line. ~ RHF . For many applications I have found balanced to be easier to cleanup from a common mode perspective then coax. But since this was a thread regarding Coax I limited my comments to Coax. Balanced has strong points. But it also is twitchy in some situations. And it is a PITA to run through a bulkhead, provide acceptable (to me) "EMP" clamps, and it must be kept well away from other conductors. In situations were you have to run feedlines adjacent to other conductors, balanced may be a bad choice. Every antenna installation is different and each site needs to be evaluated and a "plan" developed for that site. Yea, sure I sit down and design every step months before I implement. For me, other then the few commercial, IE money making, projects I have designed and built, most systems grow like a weed from something simple to something more complex. And like your garden you have to trim it up every now and then to keep it working. I used a ~100 wire on and off for 40 years. Only in the last few years have I abandoned wire antennas for active and tuned verticals. But back to coax, buy good stuff, direct burial, and invest in GOOD connectors and GOOD tools. DO NOT attempt to install "F" fittings with some pliers. Good connectors and good tools will allow you to make weather tight "F" connections that will last years. Maybe decades. Done wrong "F" fittings are dead at installation or randomly soon there after. All of my receivers use BNC, OK, my DX398 is 3.5mm but the patch goes to BNC. I use a surplus video patch panel that will pass RF up to the GPS range well enough to allow my shack GPS to stay locked. I really want to make sure my home isn't moving. It really gives a 1PPS signal to drive my ZULU/EST(EDT) clock. I do convert all my balanced back to coax at the entry bulk head. As my antenna designs change, my feedlines change to match. Balanced is always worth a try. Cheap and easy. Terry- Hide quoted text - - Show quoted text - Terry, Which Type / Types of Balanced Feed-in-Lines Do You Use : {Why?} Ready Made 300 Ohm Twin Lead ? Ready Made 450 Ohm Ladder-Line ? Standard Zip-Cord {72 Ohms} ? Standard Speaker Wire {72 Ohms} ? i want to know -cause- iane ~ RHF . . . . I use landscaping lighting cable. Measured Zo of about 150 Ohms. Standard lamp cord has about 110-130 ohms. The landscaping low voltage cable is cheap, at the end of season sales, and is very UV resistance and a robust cable. It typically is of use with high impedance antennas. This might be confusing, because Dallas Lankford's active antennas and his "15' Relay Tuned Antenna" have reasonably low output impedances, and you can change the windings or emitter resistor to tailor the impedance you want. But all of these antenna have high input impedances they can be very susceptible to common mode ingress. For these antennas, if you are going to use an above ground feed system, balanced is generally better. When expetimenting with location or new designs I tend to use balanced. And once I have the location pinned down I am now back to using coax, but I bury it at least 12" down. Balanced is nice, but the hassles of having to move it to mow are a big PITA. For an odd antenna feed line look up G-line feed. http://www.finitesite.com/wetnoodle/0013.htm Scroll down to G. http://w5jgv.com/1970_tower/tower.htm They do work very well for UHF, but for HF the launchers would get a bit unwieldy...... My current project is a slight modification to the standard Lankford 15' Relay Switched Antenna. It is elevated with a set of 16 15' elevated radials. Compared to a similar ground mounted antenna with the same number and length radials it appears the elevated 15'er is better. Due to a work related injury my right arm is imobile for another month or so, so I am not ... read more »- Hide quoted text - - Show quoted text - Terry -tyvm ~ RHF . |
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