| Page 1 of 2 | 1 | 2 |
|
|
CBS' KFWB shuts off IBOC at night
On Oct 7, 5:10 pm, David wrote:
Are they being nice or is their phasor obsolete? David, Strangely enough I was listening to them this very early morning ~3 AM and their Analog "AM" Sounded OK. ~ RHF |
CBS' KFWB shuts off IBOC at night
Are they being nice or is their phasor obsolete?
|
CBS' KFWB shuts off IBOC at night
On Oct 7, 7:41 pm, RHF wrote:
On Oct 7, 5:10 pm, David wrote: Are they being nice or is their phasor obsolete? David, Strangely enough I was listening to them this very early morning ~3 AM and their Analog "AM" Sounded OK. ~ RHF . This is exciting. AM is starting to get interesting again! |
CBS' KFWB shuts off IBOC at night
"David" wrote in message ... Are they being nice or is their phasor obsolete? Phasors can not be obsolete. They can be badly designed, hi-Q and narrowband, but there is no real change in components (coils and caps and vacuum caps) or design since the first directionals on AM were used at WSUN and WOR in the 20's. |
CBS' KFWB shuts off IBOC at night
In article ,
"David Eduardo" wrote: "David" wrote in message ... Are they being nice or is their phasor obsolete? Phasors can not be obsolete. They can be badly designed, hi-Q and narrowband, but there is no real change in components (coils and caps and vacuum caps) or design since the first directionals on AM were used at WSUN and WOR in the 20's. I suggest you put the phasors on safe before you have an accident. -- Telamon Ventura, California |
CBS' KFWB shuts off IBOC at night
On Oct 7, 6:09 pm, "David Eduardo" wrote:
"David" wrote in message ... Are they being nice or is their phasor obsolete? Phasors can not be obsolete. They can be badly designed, hi-Q and narrowband, but there is no real change in components (coils and caps and vacuum caps) or design since the first directionals on AM were used at WSUN and WOR in the 20's. The big thing for an Analog AM/MW Radio Station that is going to begin IBOC {Integrated} Analog and Digital Broadcasting : Is will their Single Tower Non-Directional Antenna handle the 30 kHz Bandwidth required of IBOC ? beyond that things get complicated -bmaoe- ~ RHF |
CBS' KFWB shuts off IBOC at night
"RHF" wrote in message ups.com... On Oct 7, 6:09 pm, "David Eduardo" wrote: "David" wrote in message ... Are they being nice or is their phasor obsolete? Phasors can not be obsolete. They can be badly designed, hi-Q and narrowband, but there is no real change in components (coils and caps and vacuum caps) or design since the first directionals on AM were used at WSUN and WOR in the 20's. The big thing for an Analog AM/MW Radio Station that is going to begin IBOC {Integrated} Analog and Digital Broadcasting : Is will their Single Tower Non-Directional Antenna handle the 30 kHz Bandwidth required of IBOC ? Most single towers are flat enough and don't have a disparate enough reactive component to do HD easily. The problem is with directional systems that were designed for easy tuning and have a high Q. These have to be broadbanded... most larger stations already did that to make analog audio sound better. |
CBS' KFWB shuts off IBOC at night
In article ,
"David Eduardo" wrote: "RHF" wrote in message ups.com... On Oct 7, 6:09 pm, "David Eduardo" wrote: "David" wrote in message ... Are they being nice or is their phasor obsolete? Phasors can not be obsolete. They can be badly designed, hi-Q and narrowband, but there is no real change in components (coils and caps and vacuum caps) or design since the first directionals on AM were used at WSUN and WOR in the 20's. The big thing for an Analog AM/MW Radio Station that is going to begin IBOC {Integrated} Analog and Digital Broadcasting : Is will their Single Tower Non-Directional Antenna handle the 30 kHz Bandwidth required of IBOC ? Most single towers are flat enough and don't have a disparate enough reactive component to do HD easily. The problem is with directional systems that were designed for easy tuning and have a high Q. These have to be broadbanded... most larger stations already did that to make analog audio sound better. You seem to have an incorrect understanding. Not surprising. -- Telamon Ventura, California |
CBS' KFWB shuts off IBOC at night
"Telamon" wrote in message ... In article , "David Eduardo" wrote: "RHF" wrote in message ups.com... On Oct 7, 6:09 pm, "David Eduardo" wrote: "David" wrote in message ... Are they being nice or is their phasor obsolete? Phasors can not be obsolete. They can be badly designed, hi-Q and narrowband, but there is no real change in components (coils and caps and vacuum caps) or design since the first directionals on AM were used at WSUN and WOR in the 20's. The big thing for an Analog AM/MW Radio Station that is going to begin IBOC {Integrated} Analog and Digital Broadcasting : Is will their Single Tower Non-Directional Antenna handle the 30 kHz Bandwidth required of IBOC ? Most single towers are flat enough and don't have a disparate enough reactive component to do HD easily. The problem is with directional systems that were designed for easy tuning and have a high Q. These have to be broadbanded... most larger stations already did that to make analog audio sound better. You seem to have an incorrect understanding. Not surprising. Please set us straight... |
CBS' KFWB shuts off IBOC at night
In article ,
"David Eduardo" wrote: "Telamon" wrote in message ... In article , "David Eduardo" wrote: "RHF" wrote in message ups.com... On Oct 7, 6:09 pm, "David Eduardo" wrote: "David" wrote in message ... Are they being nice or is their phasor obsolete? Phasors can not be obsolete. They can be badly designed, hi-Q and narrowband, but there is no real change in components (coils and caps and vacuum caps) or design since the first directionals on AM were used at WSUN and WOR in the 20's. The big thing for an Analog AM/MW Radio Station that is going to begin IBOC {Integrated} Analog and Digital Broadcasting : Is will their Single Tower Non-Directional Antenna handle the 30 kHz Bandwidth required of IBOC ? Most single towers are flat enough and don't have a disparate enough reactive component to do HD easily. The problem is with directional systems that were designed for easy tuning and have a high Q. These have to be broadbanded... most larger stations already did that to make analog audio sound better. You seem to have an incorrect understanding. Not surprising. Please set us straight... Guess where you went wrong. Give it a shot. -- Telamon Ventura, California |
CBS' KFWB shuts off IBOC at night
David Eduardo wrote: "Telamon" wrote in message ... In article , "David Eduardo" wrote: "RHF" wrote in message ups.com... On Oct 7, 6:09 pm, "David Eduardo" wrote: "David" wrote in message ... Are they being nice or is their phasor obsolete? Phasors can not be obsolete. They can be badly designed, hi-Q and narrowband, but there is no real change in components (coils and caps and vacuum caps) or design since the first directionals on AM were used at WSUN and WOR in the 20's. The big thing for an Analog AM/MW Radio Station that is going to begin IBOC {Integrated} Analog and Digital Broadcasting : Is will their Single Tower Non-Directional Antenna handle the 30 kHz Bandwidth required of IBOC ? Most single towers are flat enough and don't have a disparate enough reactive component to do HD easily. The problem is with directional systems that were designed for easy tuning and have a high Q. These have to be broadbanded... most larger stations already did that to make analog audio sound better. You seem to have an incorrect understanding. Not surprising. Please set us straight... Edweenie, you've not a clue about being straight. |
CBS' KFWB shuts off IBOC at night
"Telamon" wrote in message news:telamon_spamshield- Guess where you went wrong. Give it a shot. Most single tower AMs have more broadband ATUs than directionals. It is a lot easier to tune a directional system with high-Q circuits in the phasor, so throught the 60's, most directional systems had such narrow band, high-Q circuits. |
CBS' KFWB shuts off IBOC at night
On Oct 8, 12:23 am, "David Eduardo" wrote:
"Telamon" wrote in message news:telamon_spamshield- Guess where you went wrong. Give it a shot. Most single tower AMs have more broadband ATUs than directionals. It is a lot easier to tune a directional system with high-Q circuits in the phasor, so throught the 60's, most directional systems had such narrow band, high-Q circuits. Stuff a sock in it, Tardo. We're not talking about Star Trek. |
CBS' KFWB shuts off IBOC at night
On Sun, 7 Oct 2007 18:09:12 -0700, "David Eduardo"
wrote: "David" wrote in message .. . Are they being nice or is their phasor obsolete? Phasors can not be obsolete. They can be badly designed, hi-Q and narrowband, but there is no real change in components (coils and caps and vacuum caps) or design since the first directionals on AM were used at WSUN and WOR in the 20's. If the Q is too high for an evolved transmission scheme, and cannot be "adjusted" to a more broadband spec, the phasor is obsolete. |
CBS' KFWB shuts off IBOC at night
On Sun, 7 Oct 2007 20:13:15 -0700, "David Eduardo"
wrote: "RHF" wrote in message oups.com... On Oct 7, 6:09 pm, "David Eduardo" wrote: "David" wrote in message ... Are they being nice or is their phasor obsolete? Phasors can not be obsolete. They can be badly designed, hi-Q and narrowband, but there is no real change in components (coils and caps and vacuum caps) or design since the first directionals on AM were used at WSUN and WOR in the 20's. The big thing for an Analog AM/MW Radio Station that is going to begin IBOC {Integrated} Analog and Digital Broadcasting : Is will their Single Tower Non-Directional Antenna handle the 30 kHz Bandwidth required of IBOC ? Most single towers are flat enough and don't have a disparate enough reactive component to do HD easily. The problem is with directional systems that were designed for easy tuning and have a high Q. These have to be broadbanded... most larger stations already did that to make analog audio sound better. Until the mask... |
CBS' KFWB shuts off IBOC at night
On Oct 8, 6:25 am, David wrote:
On Sun, 7 Oct 2007 18:09:12 -0700, "David Eduardo" wrote: "David" wrote in message .. . Are they being nice or is their phasor obsolete? Phasors can not be obsolete. They can be badly designed, hi-Q and narrowband, but there is no real change in components (coils and caps and vacuum caps) or design since the first directionals on AM were used at WSUN and WOR in the 20's. - If the Q is too high for an evolved transmission scheme, and cannot - be "adjusted" to a more broadband spec, the phasor is obsolete. Set Phasors on Stun ! Beam Me Up Scotty ! - The Planet of d'Eduardo is Infested with Hispanic Radio Program Directors. jftfoi ~ RHF |
CBS' KFWB shuts off IBOC at night
"David" wrote in message ... On Sun, 7 Oct 2007 18:09:12 -0700, "David Eduardo" wrote: "David" wrote in message . .. Are they being nice or is their phasor obsolete? Phasors can not be obsolete. They can be badly designed, hi-Q and narrowband, but there is no real change in components (coils and caps and vacuum caps) or design since the first directionals on AM were used at WSUN and WOR in the 20's. If the Q is too high for an evolved transmission scheme, and cannot be "adjusted" to a more broadband spec, the phasor is obsolete. No, that is not obsolescence. That is just a design criteria. Any phasor can be broadbanded. |
CBS' KFWB shuts off IBOC at night
On Oct 8, 12:57 pm, "David Eduardo" wrote:
"David" wrote in message ... On Sun, 7 Oct 2007 18:09:12 -0700, "David Eduardo" wrote: "David" wrote in message . .. Are they being nice or is their phasor obsolete? Phasors can not be obsolete. They can be badly designed, hi-Q and narrowband, but there is no real change in components (coils and caps and vacuum caps) or design since the first directionals on AM were used at WSUN and WOR in the 20's. If the Q is too high for an evolved transmission scheme, and cannot be "adjusted" to a more broadband spec, the phasor is obsolete. No, that is not obsolescence. That is just a design criteria. Any phasor can be broadbanded.- Hide quoted text - - Show quoted text - Only Captain Kirk's is broadbanded, Tardo. |
CBS' KFWB shuts off IBOC at night
In article ,
"David Eduardo" wrote: "Telamon" wrote in message news:telamon_spamshield- Guess where you went wrong. Give it a shot. Most single tower AMs have more broadband ATUs than directionals. It is a lot easier to tune a directional system with high-Q circuits in the phasor, so throught the 60's, most directional systems had such narrow band, high-Q circuits. You don't think there might be a problem with tower itself? -- Telamon Ventura, California |
CBS' KFWB shuts off IBOC at night
In article ,
"David Eduardo" wrote: "Telamon" wrote in message ... In article , "David Eduardo" wrote: "Telamon" wrote in message news:telamon_spamshield- Guess where you went wrong. Give it a shot. Most single tower AMs have more broadband ATUs than directionals. It is a lot easier to tune a directional system with high-Q circuits in the phasor, so throught the 60's, most directional systems had such narrow band, high-Q circuits. You don't think there might be a problem with tower itself? What kind of problem do you have in mind? The FCC, for the most part requires 1/4 wave for all but class A stations, that are supposed to be 1/2 wave. There are exceptions, granted due to the lack of enough land or FAA regulations and zoning issues. I would say bandwidth. Large aspect ratio antenna elements have a narrow band of resonance. It seems to me that there are some companies out there that have tower kits that run 3 to 4 wires on spreaders so the electrical diameter of the tower is increased. This will allow the tower to have lower VSWR over the +/-15KHz required. Next up I would look at the transmission line to tower coupling. Many AM broadcast towers are series coupled with the tower isolated from ground. The tower would tune a little more broadly if it was grounded and shunt coupled. I believe this is the preferred method in central and south America. -- Telamon Ventura, California |
CBS' KFWB shuts off IBOC at night
"Telamon" wrote in message ... I would say bandwidth. Large aspect ratio antenna elements have a narrow band of resonance. It seems to me that there are some companies out there that have tower kits that run 3 to 4 wires on spreaders so the electrical diameter of the tower is increased. This will allow the tower to have lower VSWR over the +/-15KHz required. That is not the purpose of folded dipoles, called unipoles, which is what you are describing. A unipole requires no base insulator, so in this day of using towers as a revenue center, it allows other antennae to be mounted on the tower with no need of isocouplers. The feed is "found" at some point up the outrigger wires, and the base is at ground potential. The folded dipole is also appropriate, like a Franklin, when there is a bad ground system, such as antennas in marshes and salt flats where they corrode, or where there are structures on the property. A unipois also useful with a shorter than 1/4 wave tower because the tuning network needed to tune out the capacitive reactance often narrowbands the antenna (not the tower itself). So a unipole is mostly used to compensate for bad ground systems and the need to multitask the tower, not to reduce the noxious effects of a less than conforming tower, as the FCC requires a very special showing to allow low antennas. A broader cross section will broadband the tower a bit, but the difference in a 24" to 30" cross section and a folded dipole is minimal. The bandwidth for AM is, by NRSC, 10 kHz in each sideband... actually, a little less. This is to avoid 10 kHz harmonics with adjacent channels. In any event, the intent of broader bandwith would be to improve quality by decreasing the differnces in impedance and reactance at plus or minus 9.99 kHz from carrier. A well tuned ATU, whether high Q or broadbanded, does not create a significant amount of reflected power. A tower that is mismatched at carrier does. Next up I would look at the transmission line to tower coupling. Many AM broadcast towers are series coupled with the tower isolated from ground. The FCC no longer authorizes shunt fed towers. The unipole is the closest you get to this; one manufacturer, Kintronics, who makes kits to order, compares them with shunt fed systems. So, except for the unipoles, all US towers for AM are insulated from ground. Transmission lines are never couple to the tower (with maybe one or two exceptions... more later) because so few towers are a perfect impedance match with the coax and devoid of +j or -j. An antenna coupling unit is placed between the coax and the tower, using a network to match the tower to line impedance and to bring reactance to zero at the carrier. The ATU is typically attached to the tower with a copper strap, copper tubing or sometimes even braid. In any case, it is silver soldered to a connector, which is usually pressure bolted to the output of the ATU and to a leg or the base plate of the tower. There are a couple of licensed US stations that have towers in the 100 to 110 degree height range and direct couple to a series fed tower without tuning because in that degree range, occasionally a perfect match is already present. This is very rare. The tower would tune a little more broadly if it was grounded and shunt coupled. I believe this is the preferred method in central and south America. This method was used by a few high power AMs in Latin America in decades past, ones like XEB and XEW. The rest, if they have a tower (many use inverted L's of wire) use series fed towers. Since many towers are diplexed and even triplexed, a rejection network is required and that requires an ATU. Shunt fed towers are generally half wave or similar, and shunt feeding is not and has never been common with quarter wave or less towers. I have visited every AM in Mexico City, and only 3 had shunt fed towers in 1963... today, I believe only XEW has one. In Colombia, I have visited about 20 50 kw or higher sites, and none was shunt fed. In Ecuador, today and in the past, no station was shunt fed. Of the several hundred stations I visited in Central America, none was shunt fed. The most powerful AM in Argentina, Radio 10 on 710 with 100 kw, with a nice half wave tower, is series fed. The only other Latin American shunt fed I know about was CB106 Radio Mineria in Santiago. That station, saying AM was no longer viable in Chile, turned in its license and turned off the 100 kw transmitter nearly a decade ago. |
CBS' KFWB shuts off IBOC at night
In article ,
"David Eduardo" wrote: "Telamon" wrote in message ... I would say bandwidth. Large aspect ratio antenna elements have a narrow band of resonance. It seems to me that there are some companies out there that have tower kits that run 3 to 4 wires on spreaders so the electrical diameter of the tower is increased. This will allow the tower to have lower VSWR over the +/-15KHz required. That is not the purpose of folded dipoles, called unipoles, which is what you are describing. A unipole requires no base insulator, so in this day of using towers as a revenue center, it allows other antennae to be mounted on the tower with no need of isocouplers. I wasn't going after the commercial reasons but methods of causing existing towers not to be so narrowband resonant. You will find using a shunt feed method will cause the tower to be dampened compared to a series feed method. With a shunt feed the resonant peak will be a little lower and broader than with a series method. The feed is "found" at some point up the outrigger wires, and the base is at ground potential. Yes. The folded dipole is also appropriate, like a Franklin, when there is a bad ground system, such as antennas in marshes and salt flats where they corrode, or where there are structures on the property. Yeah. That's why I thought it would be more popular in central and south America where expensive or difficult to install, due to terrain, grounding systems requirements could be reduced. A unipois also useful with a shorter than 1/4 wave tower because the tuning network needed to tune out the capacitive reactance often narrowbands the antenna (not the tower itself). That my point. The shunt type coupling is more broadband. So a unipole is mostly used to compensate for bad ground systems and the need to multitask the tower, not to reduce the noxious effects of a less than conforming tower, as the FCC requires a very special showing to allow low antennas. I don't know what you mean by "the FCC requires a very special showing to allow low antennas" but I wasn't after the shorter tower aspect. A broader cross section will broadband the tower a bit, but the difference in a 24" to 30" cross section and a folded dipole is minimal. That's not my understanding. The bandwidth for AM is, by NRSC, 10 kHz in each sideband... actually, a little less. This is to avoid 10 kHz harmonics with adjacent channels. You usually make measurements beyond spec to show the trend over the entire specification. Here the spec is VSWR. In any event, the intent of broader bandwith would be to improve quality by decreasing the differnces in impedance and reactance at plus or minus 9.99 kHz from carrier. Here that results in a lower VSWR over the IBOC operating bandwidth using a shunt fed tower. A well tuned ATU, whether high Q or broadbanded, does not create a significant amount of reflected power. A tower that is mismatched at carrier does. Yes that is my point. The tower itself will have a narrow resonant bandwidth so a method is needed for the tower to not present a high VSWR +/- 15 KHz around the carrier frequency. ATU's that couple the coax transmission line to the tower using a series connection to an insulated tower have a stronger tendency to be narrowband in and of themselves. An ATU designed to couple the coax transmission line to a shunt fed tower tends to tune a little less sharply and the useful resonance range is broader. Next up I would look at the transmission line to tower coupling. Many AM broadcast towers are series coupled with the tower isolated from ground. The FCC no longer authorizes shunt fed towers. Why? The unipole is the closest you get to this; one manufacturer, Kintronics, who makes kits to order, compares them with shunt fed systems. So, except for the unipoles, all US towers for AM are insulated from ground. I don't understand why the FCC would care how transmission lines are coupled to the tower or tuned / matched by an ATU. Transmission lines are never couple to the tower (with maybe one or two exceptions... more later) because so few towers are a perfect impedance match with the coax and devoid of +j or -j. An antenna coupling unit is placed between the coax and the tower, using a network to match the tower to line impedance and to bring reactance to zero at the carrier. The ATU is typically attached to the tower with a copper strap, copper tubing or sometimes even braid. In any case, it is silver soldered to a connector, which is usually pressure bolted to the output of the ATU and to a leg or the base plate of the tower. That's all interesting information but we are mixing and matching terminology. The ATU doesn't just tune the tower to resonance it is also a part of circuitry that couples the transmission line to the tower. Reactance is near zero at resonance and the antenna looks like a resistive load to the transmission line. The resistive load value also needs to match the line impedance so there is little or no reflective power. This is one reason why transmitters are getting damaged when IBOC is turned on. The reflective power goes up over the increased power bandwidth IBOC requires. Several things happen when the reflected power goes up. Mainly the power does not go into the antenna to be radiated and instead heats the transmission line and transmitter finals. Another bad effect is the reflected power can make the transmitter unstable and generate spurious energy. There are a couple of licensed US stations that have towers in the 100 to 110 degree height range and direct couple to a series fed tower without tuning because in that degree range, occasionally a perfect match is already present. This is very rare. Perfectly understandable. The tower would tune a little more broadly if it was grounded and shunt coupled. I believe this is the preferred method in central and south America. This method was used by a few high power AMs in Latin America in decades past, ones like XEB and XEW. The rest, if they have a tower (many use inverted L's of wire) use series fed towers. Since many towers are diplexed and even triplexed, a rejection network is required and that requires an ATU. Shunt fed towers are generally half wave or similar, and shunt feeding is not and has never been common with quarter wave or less towers. I have visited every AM in Mexico City, and only 3 had shunt fed towers in 1963... today, I believe only XEW has one. In Colombia, I have visited about 20 50 kw or higher sites, and none was shunt fed. In Ecuador, today and in the past, no station was shunt fed. Of the several hundred stations I visited in Central America, none was shunt fed. The most powerful AM in Argentina, Radio 10 on 710 with 100 kw, with a nice half wave tower, is series fed. The only other Latin American shunt fed I know about was CB106 Radio Mineria in Santiago. That station, saying AM was no longer viable in Chile, turned in its license and turned off the 100 kw transmitter nearly a decade ago. You sure get around. -- Telamon Ventura, California |
CBS' KFWB shuts off IBOC at night
"Telamon" wrote in message ... In article , "David Eduardo" wrote: The folded dipole is also appropriate, like a Franklin, when there is a bad ground system, such as antennas in marshes and salt flats where they corrode, or where there are structures on the property. Yeah. That's why I thought it would be more popular in central and south America where expensive or difficult to install, due to terrain, grounding systems requirements could be reduced. Why would the terrain considerations, grounding requirements and such be any different than in, say, Idaho or Wisconsin or Arizona or Alabama? And why would it be more expensive to do in Central and South America? I can see no logic in any of this set of statements. A unipois also useful with a shorter than 1/4 wave tower because the tuning network needed to tune out the capacitive reactance often narrowbands the antenna (not the tower itself). That my point. The shunt type coupling is more broadband. Only for very short towers where a high capacitive reactance is found. Otherwise, the bandwidth is much more the effect of the Q of the ATU and the trandsmitter itself. So a unipole is mostly used to compensate for bad ground systems and the need to multitask the tower, not to reduce the noxious effects of a less than conforming tower, as the FCC requires a very special showing to allow low antennas. I don't know what you mean by "the FCC requires a very special showing to allow low antennas" but I wasn't after the shorter tower aspect. That is the only place where the unipole offers a distinct bandwidth advantage. It also gets a better field strength at 1 km than a short series fed tower. But the main reason anyone uses them is either due to a bad ground or the need to put other antennas on the tower. A broader cross section will broadband the tower a bit, but the difference in a 24" to 30" cross section and a folded dipole is minimal. That's not my understanding. Go back to Carl Smith's AM antenna and DA handbooks, Unless you find a nice old Blaw Knox with a 24 foot center cross section, there is not much gain except cost, maintenance, etc., in adding outriggers insofar as broadbanding. The bandwidth for AM is, by NRSC, 10 kHz in each sideband... actually, a little less. This is to avoid 10 kHz harmonics with adjacent channels. You usually make measurements beyond spec to show the trend over the entire specification. Here the spec is VSWR. A well tuned tower of 1/4 wave has less than 1.08 to 1 vizwar. And, except for test situations, a tower measurement is usually done at -10, licenced frequency and +10 kHz. This is what is often asked for by outside fabricators of ATUs. A well tuned ATU, whether high Q or broadbanded, does not create a significant amount of reflected power. A tower that is mismatched at carrier does. Yes that is my point. The tower itself will have a narrow resonant bandwidth so a method is needed for the tower to not present a high VSWR +/- 15 KHz around the carrier frequency. A mismatch is generally considered to be a mismatch of impedance output of the ATU with the tower itself at the fundamental. Since the audio is brick-walled right under 10 kHz, there should be little or no excursions beyond +/- 10 kHz. ATU's that couple the coax transmission line to the tower using a series connection to an insulated tower have a stronger tendency to be narrowband in and of themselves. Not for the last 40 years or so. High Q was much more common pre-60's when AMs mostly ran network showsthat came over 5 kHz lines from very far away. When music took over AM, stations wanted better bandwidth. An ATU designed to couple the coax transmission line to a shunt fed tower tends to tune a little less sharply and the useful resonance range is broader. Since true shunts are no longer licensed, this point is moot. Most US AMs, for economy, zoning, FAA, etc. use quarter wave series fed towers. Since a huge percentage are directional, there are very, very few Unipole directionals, so in that area series fed is the only way to go. The FCC no longer authorizes shunt fed towers. Why? I don't know. This has been the case for many decades. I suspect part has to do with the slight directionality the shunt itself introduces, and the fact that shunts would be very difficult to do with directional stations for this reason. The unipole is the closest you get to this; one manufacturer, Kintronics, who makes kits to order, compares them with shunt fed systems. So, except for the unipoles, all US towers for AM are insulated from ground. I don't understand why the FCC would care how transmission lines are coupled to the tower or tuned / matched by an ATU. There is a lot about AM radio in the US you don't understand. The fact is, shunt fed towers are very seldom used. I suspect that the fact that they are not particulary easy to tune on short, 1/2 wave towers may be part of it, but there must be more. Transmission lines are never couple to the tower (with maybe one or two exceptions... more later) because so few towers are a perfect impedance match with the coax and devoid of +j or -j. An antenna coupling unit is placed between the coax and the tower, using a network to match the tower to line impedance and to bring reactance to zero at the carrier. The ATU is typically attached to the tower with a copper strap, copper tubing or sometimes even braid. In any case, it is silver soldered to a connector, which is usually pressure bolted to the output of the ATU and to a leg or the base plate of the tower. That's all interesting information but we are mixing and matching terminology. The ATU doesn't just tune the tower to resonance it is also a part of circuitry that couples the transmission line to the tower. An ATU is not necessary if the tower is 52 ohms and not reactive, found around about 100 to 110 degrees in electrical height. The ATU is a matching circuit, to make the coax "see" 52 ohms (or some other impedance) when, in fact, the tower is not of that impedance. In some senses, a top hat or top loading does the same thing... it makes the tower change the apparent electrical height. You are trying to complicate something that is relatively simple... cancelling the reactance and matching impedance. Reactance is near zero at resonance and the antenna looks like a resistive load to the transmission line. The resistive load value also needs to match the line impedance so there is little or no reflective power. This is one reason why transmitters are getting damaged when IBOC is turned on. The reflective power goes up over the increased power bandwidth IBOC requires. That is not why the very few cases of transmitter damage have occured. Most transmitters will simply shut down over reactive or mismatched loads. The issues reported (and one that took out 80% of the power modules at KTNQ) had to do with the control interface of the HD exciter and the analog transmitter.... a design defect in non-rf and non-af circuitry. Several things happen when the reflected power goes up. Mainly the power does not go into the antenna to be radiated and instead heats the transmission line and transmitter finals. Another bad effect is the reflected power can make the transmitter unstable and generate spurious energy. Or, in today's transmitters, it does neither. It detects VSWR and shuts off. .. This method was used by a few high power AMs in Latin America in decades past, ones like XEB and XEW. The rest, if they have a tower (many use inverted L's of wire) use series fed towers. Since many towers are diplexed and even triplexed, a rejection network is required and that requires an ATU. Shunt fed towers are generally half wave or similar, and shunt feeding is not and has never been common with quarter wave or less towers. I have visited every AM in Mexico City, and only 3 had shunt fed towers in 1963... today, I believe only XEW has one. In Colombia, I have visited about 20 50 kw or higher sites, and none was shunt fed. In Ecuador, today and in the past, no station was shunt fed. Of the several hundred stations I visited in Central America, none was shunt fed. The most powerful AM in Argentina, Radio 10 on 710 with 100 kw, with a nice half wave tower, is series fed. The only other Latin American shunt fed I know about was CB106 Radio Mineria in Santiago. That station, saying AM was no longer viable in Chile, turned in its license and turned off the 100 kw transmitter nearly a decade ago. You sure get around. Yes, I have worked in every nation in Latin America save Cuba and Nicaragua, and visited stations in each one. There are pictures of dozens and dozens stations I took, including some shunt fed ones, on my web page, from trips I made visiting stations. The fact is you have said that shunt feeding is common in Latin America where it is highly uncommon and always has been. You made statements about costs, land and towers in Latin America that make it sound like you think we are talking about another planet, not the same Hemisphere. In fact, the conditions and terrain in South Florida are more difficult and hostile than in most places in Latin America. |
CBS' KFWB shuts off IBOC at night
"David" wrote in message ... On Tue, 9 Oct 2007 19:01:29 -0700, "David Eduardo" wrote: The bandwidth for AM is, by NRSC, 10 kHz in each sideband... actually, a little less. This is to avoid 10 kHz harmonics with adjacent channels. Not harmonics, just plain old splatter. Sorry. The word should have been heterodynes. |
CBS' KFWB shuts off IBOC at night
On Tue, 9 Oct 2007 19:01:29 -0700, "David Eduardo"
wrote: The bandwidth for AM is, by NRSC, 10 kHz in each sideband... actually, a little less. This is to avoid 10 kHz harmonics with adjacent channels. Not harmonics, just plain old splatter. There are a couple of licensed US stations that have towers in the 100 to 110 degree height range and direct couple to a series fed tower without tuning because in that degree range, occasionally a perfect match is already present. This is very rare. 5/8 wave is magic. |
CBS' KFWB shuts off IBOC at night
On Wed, 10 Oct 2007 04:19:00 GMT, Telamon
wrote: I don't understand why the FCC would care how transmission lines are coupled to the tower or tuned / matched by an ATU. An influential senator has an interest in a company that makes base insulators? |
CBS' KFWB shuts off IBOC at night
On Oct 10, 9:41 am, "David Eduardo" wrote:
"David" wrote in message ... On Tue, 9 Oct 2007 19:01:29 -0700, "David Eduardo" wrote: The bandwidth for AM is, by NRSC, 10 kHz in each sideband... actually, a little less. This is to avoid 10 kHz harmonics with adjacent channels. Not harmonics, just plain old splatter. Sorry. The word should have been heterodynes. Actually, your word should have been "I'm sorry for lying about my academic history, name, job title, having a ham license and so on." |
CBS' KFWB shuts off IBOC at night
On Oct 7, 9:09 pm, "David Eduardo" wrote:
"David" wrote in message ... Are they being nice or is their phasor obsolete? Phasors can not be obsolete. They can be badly designed, hi-Q and narrowband, but there is no real change in components (coils and caps and vacuum caps) or design since the first directionals on AM were used at WSUN and WOR in the 20's. How do you know such technical stuff - you are only a high-school dropout, so you must have crib sheets for all of your answers, or look it up on the Web before you post. |
CBS' KFWB shuts off IBOC at night
On Oct 8, 12:23 am, "David Eduardo" wrote:
"Telamon" wrote in message news:telamon_spamshield- Guess where you went wrong. Give it a shot. Most single tower AMs have more broadband ATUs than directionals. It is a lot easier to tune a directional system with high-Q circuits in the phasor, so throught the 60's, most directional systems had such narrow band, high-Q circuits. Now, do you feel on the same level,as us college grads? |
CBS' KFWB shuts off IBOC at night
On Oct 10, 9:41 am, "David Eduardo" wrote:
"David" wrote in message ... On Tue, 9 Oct 2007 19:01:29 -0700, "David Eduardo" wrote: The bandwidth for AM is, by NRSC, 10 kHz in each sideband... actually, a little less. This is to avoid 10 kHz harmonics with adjacent channels. Not harmonics, just plain old splatter. Sorry. The word should have been heterodynes. Got mixed up reading from your book, eh? |
CBS' KFWB shuts off IBOC at night
"IBOCcrock" wrote in message ps.com... On Oct 7, 9:09 pm, "David Eduardo" wrote: "David" wrote in message ... Are they being nice or is their phasor obsolete? Phasors can not be obsolete. They can be badly designed, hi-Q and narrowband, but there is no real change in components (coils and caps and vacuum caps) or design since the first directionals on AM were used at WSUN and WOR in the 20's. How do you know such technical stuff - you are only a high-school dropout, so you must have crib sheets for all of your answers, or look it up on the Web before you post. I did many home study courses in electronics from CEI, National Radio Institute, etc., in order to build and maintain my stations in Ecuador. I have had an FCC First Class License (now General) for nearly four decades. |
CBS' KFWB shuts off IBOC at night
David Eduardo wrote: "IBOCcrock" wrote in message ps.com... On Oct 7, 9:09 pm, "David Eduardo" wrote: "David" wrote in message ... Are they being nice or is their phasor obsolete? Phasors can not be obsolete. They can be badly designed, hi-Q and narrowband, but there is no real change in components (coils and caps and vacuum caps) or design since the first directionals on AM were used at WSUN and WOR in the 20's. How do you know such technical stuff - you are only a high-school dropout, so you must have crib sheets for all of your answers, or look it up on the Web before you post. I did many home study courses in electronics from CEI, National Radio Institute, etc., in order to build and maintain my stations in Ecuador. I have had an FCC First Class License (now General) for nearly four decades. Records seem to indicate you received the FCC license in 1974 using the name "David Frackelton Gleason". |
CBS' KFWB shuts off IBOC at night
"dxAce" wrote in message ... David Eduardo wrote: "IBOCcrock" wrote in message ps.com... On Oct 7, 9:09 pm, "David Eduardo" wrote: "David" wrote in message ... Are they being nice or is their phasor obsolete? Phasors can not be obsolete. They can be badly designed, hi-Q and narrowband, but there is no real change in components (coils and caps and vacuum caps) or design since the first directionals on AM were used at WSUN and WOR in the 20's. How do you know such technical stuff - you are only a high-school dropout, so you must have crib sheets for all of your answers, or look it up on the Web before you post. I did many home study courses in electronics from CEI, National Radio Institute, etc., in order to build and maintain my stations in Ecuador. I have had an FCC First Class License (now General) for nearly four decades. Records seem to indicate you received the FCC license in 1974 using the name "David Frackelton Gleason". Wrong. I received it in 1969 at the FCC offices on M Street in DC. |
CBS' KFWB shuts off IBOC at night
David Eduardo wrote: "dxAce" wrote in message ... David Eduardo wrote: "IBOCcrock" wrote in message ps.com... On Oct 7, 9:09 pm, "David Eduardo" wrote: "David" wrote in message ... Are they being nice or is their phasor obsolete? Phasors can not be obsolete. They can be badly designed, hi-Q and narrowband, but there is no real change in components (coils and caps and vacuum caps) or design since the first directionals on AM were used at WSUN and WOR in the 20's. How do you know such technical stuff - you are only a high-school dropout, so you must have crib sheets for all of your answers, or look it up on the Web before you post. I did many home study courses in electronics from CEI, National Radio Institute, etc., in order to build and maintain my stations in Ecuador. I have had an FCC First Class License (now General) for nearly four decades. Records seem to indicate you received the FCC license in 1974 using the name "David Frackelton Gleason". Wrong. I received it in 1969 at the FCC offices on M Street in DC. You'd better check your records! |
CBS' KFWB shuts off IBOC at night
On Oct 10, 2:27 pm, dxAce wrote:
David Eduardo wrote: "dxAce" wrote in message ... David Eduardo wrote: "IBOCcrock" wrote in message oups.com... On Oct 7, 9:09 pm, "David Eduardo" wrote: "David" wrote in message . .. Are they being nice or is their phasor obsolete? Phasors can not be obsolete. They can be badly designed, hi-Q and narrowband, but there is no real change in components (coils and caps and vacuum caps) or design since the first directionals on AM were used at WSUN and WOR in the 20's. How do you know such technical stuff - you are only a high-school dropout, so you must have crib sheets for all of your answers, or look it up on the Web before you post. I did many home study courses in electronics from CEI, National Radio Institute, etc., in order to build and maintain my stations in Ecuador. I have had an FCC First Class License (now General) for nearly four decades. Records seem to indicate you received the FCC license in 1974 using the name "David Frackelton Gleason". Wrong. I received it in 1969 at the FCC offices on M Street in DC. You'd better check your records!- Hide quoted text - - Show quoted text - Good grief, is it possible that this guy's been caught in yet ANOTHER lie? Tardo, you might want to try telling the truth. Your attempts at deception just aren't working for you. |
CBS' KFWB shuts off IBOC at night
"dxAce" wrote in message ... Records seem to indicate you received the FCC license in 1974 using the name "David Frackelton Gleason". Wrong. I received it in 1969 at the FCC offices on M Street in DC. You'd better check your records! You are looking at a renewal certificate on my website. |
CBS' KFWB shuts off IBOC at night
David Frackelton Gleason, caught lying again whilst posing as 'Eduardo', wrote: "dxAce" wrote in message ... Records seem to indicate you received the FCC license in 1974 using the name "David Frackelton Gleason". Wrong. I received it in 1969 at the FCC offices on M Street in DC. You'd better check your records! You are looking at a renewal certificate on my website. Really? Well, after looking at records I have in hand, and now checking your website I see that you indeed have the original certificate there (dated 1974). And right above that it states "1970. The economic situation in Ecuador looked to be rapidly deteriorating, with runaway inflation, currency controls and shortages of everything. For 6 months, I lived in Washington, D.C. while preparing for the F.C.C. First Class Radiotelephone operator’s license." So, which is correct? You lived in Washington for 6 months (in 1970) preparing for a test that you didn't pass until 1974? (And mind you, there is no mention on your website of obtaining an FCC license in 1969). Somehow I don't think that the FCC is lying to me! dxAce Michigan USA Don't do business with the Huntington Investment Company. |
CBS' KFWB shuts off IBOC at night
David Eduardo wrote: "dxAce" wrote in message ... Records seem to indicate you received the FCC license in 1974 using the name "David Frackelton Gleason". Wrong. I received it in 1969 at the FCC offices on M Street in DC. You'd better check your records! You are looking at a renewal certificate on my website. At least you gave them your legally correct name! |
CBS' KFWB shuts off IBOC at night
Steve wrote: On Oct 10, 2:27 pm, dxAce wrote: David Eduardo wrote: "dxAce" wrote in message ... David Eduardo wrote: "IBOCcrock" wrote in message oups.com... On Oct 7, 9:09 pm, "David Eduardo" wrote: "David" wrote in message . .. Are they being nice or is their phasor obsolete? Phasors can not be obsolete. They can be badly designed, hi-Q and narrowband, but there is no real change in components (coils and caps and vacuum caps) or design since the first directionals on AM were used at WSUN and WOR in the 20's. How do you know such technical stuff - you are only a high-school dropout, so you must have crib sheets for all of your answers, or look it up on the Web before you post. I did many home study courses in electronics from CEI, National Radio Institute, etc., in order to build and maintain my stations in Ecuador. I have had an FCC First Class License (now General) for nearly four decades. Records seem to indicate you received the FCC license in 1974 using the name "David Frackelton Gleason". Wrong. I received it in 1969 at the FCC offices on M Street in DC. You'd better check your records!- Hide quoted text - - Show quoted text - Good grief, is it possible that this guy's been caught in yet ANOTHER lie? Tardo, you might want to try telling the truth. Your attempts at deception just aren't working for you. He's mulling over a way to get out of this one! |
CBS' KFWB shuts off IBOC at night
David Eduardo wrote: "dxAce" wrote in message ... David Eduardo wrote: "IBOCcrock" wrote in message ps.com... On Oct 7, 9:09 pm, "David Eduardo" wrote: "David" wrote in message ... Are they being nice or is their phasor obsolete? Phasors can not be obsolete. They can be badly designed, hi-Q and narrowband, but there is no real change in components (coils and caps and vacuum caps) or design since the first directionals on AM were used at WSUN and WOR in the 20's. How do you know such technical stuff - you are only a high-school dropout, so you must have crib sheets for all of your answers, or look it up on the Web before you post. I did many home study courses in electronics from CEI, National Radio Institute, etc., in order to build and maintain my stations in Ecuador. I have had an FCC First Class License (now General) for nearly four decades. Records seem to indicate you received the FCC license in 1974 using the name "David Frackelton Gleason". Wrong. I received it in 1969 at the FCC offices on M Street in DC. So, in what year did you receive your non-existent amateur radio license? |
| All times are GMT +1. The time now is 01:14 AM. |
|
Powered by vBulletin® Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
RadioBanter.com