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CBS' KFWB shuts off IBOC at night
On Oct 10, 2:51 pm, dxAce wrote:
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!- Hide quoted text - - Show quoted text - This is freaking amazing. This idiot would lie about what he ate for breakfast! |
CBS' KFWB shuts off IBOC at night
Steve wrote: On Oct 10, 2:51 pm, dxAce wrote: 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!- Hide quoted text - - Show quoted text - This is freaking amazing. This idiot would lie about what he ate for breakfast! Yes, he would. It's an illness over which he's obviously had no control. |
CBS' KFWB shuts off IBOC at night
"Steve" wrote in message ups.com... On Oct 10, 2:27 pm, dxAce wrote: 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. The 1974 license on my website is a RENEWAL. In fact, until the 70's, the old license was not returned. If this bothers you so much, write to the FCC. |
CBS' KFWB shuts off IBOC at night
"dxAce" wrote in message ... 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). When I got the renewal in 1979 of the 1974 license, also a renewal, the FCC had begun to cancel and return the old license, just like they do with passports. The original issue, if we count back, could have been late '69 or early '70... it was normal to submit a renewal application quite a few months in advance. And that is all we are dealing with... was it the last month or two of one year or the first month or two of another. The fact is, when things got sticky in Ecuador, I traveled many times to the US, even to Pocatello, ID, where I interviewed with Dan Libeg at a Top 40 station there. Since station owners have nearly unlimited air travel and due bills, it was easy to go and find out what might be available. I even interviewed in Mexico City with ORC and Acir... You sure get into an uproar over a matter of months, something that does not change the fact I had a 1st ticket... demonstrating I passed the FCC set of three exams. 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." Yeah, it was either late 69 or early 1970 when I got the first license. I don't think that the day and month matter at all... 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). So? It may have been late 69 or early 70. I really have no precise recollection.... the date is somewhere in that vicinity. What, really, is a couple of months? If it matters so to you, ask the FCC. |
CBS' KFWB shuts off IBOC at night
"dxAce" wrote in message ... David Eduardo wrote: 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? The authorization, which was not a license certificate, but an "oficio" was in '66 or '67. |
CBS' KFWB shuts off IBOC at night
On Oct 10, 5:16 pm, "David Eduardo" wrote:
"Steve" wrote in message ups.com... On Oct 10, 2:27 pm, dxAce wrote: 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. The 1974 license on my website is a RENEWAL. In fact, until the 70's, the old license was not returned. If this bothers you so much, write to the FCC. Tardo, nothing you do bothers me. I can count on you for at least one good laugh each day. It's a good thing. |
CBS' KFWB shuts off IBOC at night
Steve wrote: On Oct 10, 5:16 pm, "David Eduardo" wrote: "Steve" wrote in message ups.com... On Oct 10, 2:27 pm, dxAce wrote: 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. The 1974 license on my website is a RENEWAL. In fact, until the 70's, the old license was not returned. If this bothers you so much, write to the FCC. Tardo, nothing you do bothers me. I can count on you for at least one good laugh each day. It's a good thing. Yes, it is. Edweenie is at least good for a laugh. dxAce Michigan USA |
CBS' KFWB shuts off IBOC at night
David Eduardo wrote: "dxAce" wrote in message ... 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). When I got the renewal in 1979 of the 1974 license, also a renewal, the FCC had begun to cancel and return the old license, just like they do with passports. The original issue, if we count back, could have been late '69 or early '70... it was normal to submit a renewal application quite a few months in advance. And that is all we are dealing with... was it the last month or two of one year or the first month or two of another. The fact is, when things got sticky in Ecuador, I traveled many times to the US, even to Pocatello, ID, where I interviewed with Dan Libeg at a Top 40 station there. Since station owners have nearly unlimited air travel and due bills, it was easy to go and find out what might be available. I even interviewed in Mexico City with ORC and Acir... You sure get into an uproar over a matter of months, something that does not change the fact I had a 1st ticket... demonstrating I passed the FCC set of three exams. 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." Yeah, it was either late 69 or early 1970 when I got the first license. I don't think that the day and month matter at all... 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). So? It may have been late 69 or early 70. I really have no precise recollection.... the date is somewhere in that vicinity. What, really, is a couple of months? If it matters so to you, ask the FCC. A couple of months? To a pathological liar such as yourself, obviously nothing. Don't stay up to late trying to correct your pathetic website. dxAce Michigan USA |
CBS' KFWB shuts off IBOC at night
David Eduardo wrote: "Steve" wrote in message ups.com... On Oct 10, 2:27 pm, dxAce wrote: 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. The 1974 license on my website is a RENEWAL. NOT! |
CBS' KFWB shuts off IBOC at night
David Eduardo wrote: "dxAce" wrote in message ... David Eduardo wrote: 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? The authorization, which was not a license certificate, but an "oficio" was in '66 or '67. Guess that's why it never shows up anywhere! "oficio" must mean "faux". I'm LMFAO you f00kin fake!. |
CBS' KFWB shuts off IBOC at night
"dxAce" wrote in message ... David Eduardo wrote: "Steve" wrote in message ups.com... On Oct 10, 2:27 pm, dxAce wrote: 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. The 1974 license on my website is a RENEWAL. NOT! Since I was chief operator of WUNO from late '70 to mid-'72, and that requires not only a 1st ticket but notification of the Engineer in Charge of the FCC field office, there is, no doubt, somewhere record of it. |
CBS' KFWB shuts off IBOC at night
"dxAce" wrote in message ... David Eduardo wrote: "dxAce" wrote in message ... David Eduardo wrote: 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? The authorization, which was not a license certificate, but an "oficio" was in '66 or '67. Guess that's why it never shows up anywhere! "oficio" must mean "faux". An "oficio" is basically an "edict" and is a folio with fiscal stamps and a notification text. |
CBS' KFWB shuts off IBOC at night
In article ,
"David Eduardo" wrote: "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? They would not and since when is Idaho, Wisconsin, Arizona or Alabama in south America? 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. Where did I say it was more expensive in SA? The logic is why spend money you don't have to spend. The problem looks to be reading comprehension. 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. No. 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. I don't have that book so I can't do that but general theory would indicate otherwise and there are companies that offer tower kits to improve bandwidth performance as I have described. 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. Again that is not my understanding of tower VSWR. The levels at 5, 10, and 15 KHz are much higher than you indicate, which requires mitigation efforts. 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. For analog +/- 10 KHz sounds reasonable but it looks like IBOC is going past that number. The testing recommendation I read suggests testing to +/- 15 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. I don't see how that can be improved. Series feeding the tower will require a fairly high Q network that is inherently narrow band compared to a shunt feed method. 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. I don't see where you keep on this tack about Unipoles as they can just as easily be part of a directional network. 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. I don't see where a Unipole would present a problem in a directional network. 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. Yeah, there must be another reason. 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. That's fine if the coax and transmitter output impedance is 52 ohms. I didn't realize I was making it more complicated I was just trying to explain the dynamics of tuning the tower. An ATU is usually necessary. 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. Wow, I guess the engineering of the IBOC working group really sucks. I figured something in the way of the application in the field is what would bring things down. This is far worse that I imagined. 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. And all my equipment has fuses or circuit breakers but I usually apply effort toward making sure they are not used. 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. I don't see the need to be so defensive about what I posted. I made it clear it was an assumption and explained my logic for those assumptions. The reasoning was technical and there is no need to try to make it into something else. -- Telamon Ventura, California |
CBS' KFWB shuts off IBOC at night
In article ,
David wrote: 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? Very funny. -- Telamon Ventura, California |
CBS' KFWB shuts off IBOC at night
In article ,
"Brenda Ann" 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. I've been in on installing one of those kits.. lot of fun when you have the backup tower for the station only a few dozens of yards away.. you don't want to forget to connect that ground in at least two places on the way down the tower.. :) That's great. Tell us how it works out when you tune it up. -- Telamon Ventura, California |
CBS' KFWB shuts off IBOC at night
"Telamon" wrote in message ... In article , "David Eduardo" wrote: 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? They would not and since when is Idaho, Wisconsin, Arizona or Alabama in south America? I asked why South or Central America would have conditions of terrain, grounding or cost any different than those states? I have no idea why you think a unipole would be of any greater advantage there than in, say, Lake City, FL? Why? In a simple sentence; why would grounding be different than in the US. Another: why would the terrain be different than in the US? 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. Where did I say it was more expensive in SA? You said that Latin America is "where (it is) expensive to install..." And I do not see that it is expensive at all, and where a unipole would be less expensive. The logic is why spend money you don't have to spend. The problem looks to be reading comprehension. Importing a unipole kit from the US (nobody makes them or uses them in Latin America) and bringing in an experiienced installer would be much more expensive than a simple to build and maintain series fed antenna. Every nation in Latin America has a local tower fabricator and erector or two. 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. No. You obviously have not measured may, if any, AM vertical radiators. Untill they get very wide, like the old towers of the 20's and 30's which were built like scaffolding, there is no appreciale benefit in width, and the cost at any optimum point is prohibitative and likely will get no zoning clearance. The problem with bandwidth can be solved by ATU design, and VSWR reduced to less than 1.09 to 1 at 10 kHz with ease. 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. I don't have that book so I can't do that but general theory would indicate otherwise and there are companies that offer tower kits to improve bandwidth performance as I have described. The purpose of a unipole is to allow the tower to be at ground potential so we can get point to point and other antenna rentals without isocouplers. It is also to compensate for bad grounds, like where a parking lot and shopping center now sit on the ground system. Bandwidth is mostly enhanced below 1/4 wave, and the FCC only licences such towers under extreme circumstances... very few towers under 90 degrees exist in the US. I've seen a bunch of non-licensed stations, such as AFRTS facilities using them though.... 1040 at Ft. Brook used one to tune a roughly 75 foot tower and it did not sound too dreadful, either. Rame, on 780, used one on a 50 foot tower, also. 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. Again that is not my understanding of tower VSWR. The levels at 5, 10, and 15 KHz are much higher than you indicate, which requires mitigation efforts. The ATU will generally create a 52 ohm match at carrier, and j 0. At plus or minus 10 kHz, we would look for well under 1.1 to 1 VSWR with a good ATU. They can be designed to give even less than that, but considering the amount of entergy under NRSC at 10 kHz is minimal, that is often good enough. 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. For analog +/- 10 KHz sounds reasonable but it looks like IBOC is going past that number. The testing recommendation I read suggests testing to +/- 15 KHz. The stations for which AM HD is even appropriate are major stations in each market only... and most of these have nicely designed antennas. The very directional stations are going to have more problems in the phasor than in the ATU and tower. Phasors have to be a compromise of tunability (High Q) and bandwidth... so the bottleneck is in the phasor, the rest of the system being infinitely more tolerant. 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. I don't see how that can be improved. Series feeding the tower will require a fairly high Q network that is inherently narrow band compared to a shunt feed method. The kind of network and the network design can make a pretty decent broadbanding within licensed bandwith possible. In any case, you are not going to get a shunt fed tower in the US, and you are not going to get shunt fed directionals anywhere. 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. I don't see where you keep on this tack about Unipoles as they can just as easily be part of a directional network. Shunt fed towers tend to have slight directionality, and unipoles have enormous mechanical instability, making adjusting a unipole directional and meeting licensing requirements something that might not even be possible. And the cost of readjusting as the outriggers move about and the wires strech and age would be huge... most station engineers do not adjust their own directionals... a consulting engineer does, at great cost. I don't see where a Unipole would present a problem in a directional network. See above. Mechanical stability is the first issue. 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. That's fine if the coax and transmitter output impedance is 52 ohms. I didn't realize I was making it more complicated I was just trying to explain the dynamics of tuning the tower. How many towers have you tuned? An ATU is usually necessary. Always unless there is a perfect match. I chatted with some engineers who are into this sort of thing, and we came up with one station in the west, the 1590 in the Victor Valley about two decades ago... it has since moved and has a doghouse at the tower base, now. 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. Wow, I guess the engineering of the IBOC working group really sucks. I figured something in the way of the application in the field is what would bring things down. This is far worse that I imagined. iBiquity does not design exciters. In this case, the HD exciter was built by one of the big three transmitter companies, and it had a "design mismatch" (read "flaw") when mated to one particular transmitter which they did not even manufacture. It's the price stations pay for being early on the curve... which is usual in major markets because, problem and all, such stations have at least one backup transmitter, and many have two. Or, in today's transmitters, it does neither. It detects VSWR and shuts off. And all my equipment has fuses or circuit breakers but I usually apply effort toward making sure they are not used. In the case of transmitters, the control circuit performs system shutdown or power reduction to protect itself without fuses or circuit breakers; a high VSWR might cause a transmitter to progressively fall back to half power, half again, and so on until it can operate... or it shuts off. 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. I don't see the need to be so defensive about what I posted. I made it clear it was an assumption and explained my logic for those assumptions. The reasoning was technical and there is no need to try to make it into something else. In that case, I do apologize. I may have mistakenly thought you were one of the multitude that thinks that all of Latin America consists of terrain that can only be found in an Indiana Jones movie; the fact is that the land anywhere there is comparable to some place in the US. Towers tend to cost less, as they are locally fabricated and the labor costs are lower; ATUs and such can be made from off the shelf caps and coils you can wind from automotive AC tubing if the need arises. |
CBS' KFWB shuts off IBOC at night
On Oct 10, 11:17 pm, "David Eduardo" wrote:
"Telamon" wrote in message ... In article , "David Eduardo" wrote: 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? They would not and since when is Idaho, Wisconsin, Arizona or Alabama in south America? I asked why South or Central America would have conditions of terrain, grounding or cost any different than those states? I have no idea why you think a unipole would be of any greater advantage there than in, say, Lake City, FL? Why? In a simple sentence; why would grounding be different than in the US. Another: why would the terrain be different than in the US? 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. Where did I say it was more expensive in SA? You said that Latin America is "where (it is) expensive to install..." And I do not see that it is expensive at all, and where a unipole would be less expensive. The logic is why spend money you don't have to spend. The problem looks to be reading comprehension. Importing a unipole kit from the US (nobody makes them or uses them in Latin America) and bringing in an experiienced installer would be much more expensive than a simple to build and maintain series fed antenna. Every nation in Latin America has a local tower fabricator and erector or two. 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. No. You obviously have not measured may, if any, AM vertical radiators. Untill they get very wide, like the old towers of the 20's and 30's which were built like scaffolding, there is no appreciale benefit in width, and the cost at any optimum point is prohibitative and likely will get no zoning clearance. The problem with bandwidth can be solved by ATU design, and VSWR reduced to less than 1.09 to 1 at 10 kHz with ease. 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. I don't have that book so I can't do that but general theory would indicate otherwise and there are companies that offer tower kits to improve bandwidth performance as I have described. The purpose of a unipole is to allow the tower to be at ground potential so we can get point to point and other antenna rentals without isocouplers. It is also to compensate for bad grounds, like where a parking lot and shopping center now sit on the ground system. Bandwidth is mostly enhanced below 1/4 wave, and the FCC only licences such towers under extreme circumstances... very few towers under 90 degrees exist in the US. I've seen a bunch of non-licensed stations, such as AFRTS facilities using them though.... 1040 at Ft. Brook used one to tune a roughly 75 foot tower and it did not sound too dreadful, either. Rame, on 780, used one on a 50 foot tower, also. 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. Again that is not my understanding of tower VSWR. The levels at 5, 10, and 15 KHz are much higher than you indicate, which requires mitigation efforts. The ATU will generally create a 52 ohm match at carrier, and j 0. At plus or minus 10 kHz, we would look for well under 1.1 to 1 VSWR with a good ATU. They can be designed to give even less than that, but considering the amount of entergy under NRSC at 10 kHz is minimal, that is often good enough. 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. For analog +/- 10 KHz sounds reasonable but it looks like IBOC is going past that number. The testing recommendation I read suggests testing to +/- 15 KHz. The stations for which AM HD is even appropriate are major stations in each market only... and most of these have nicely designed antennas. The very directional stations are going to have more problems in the phasor than in the ATU and tower. Phasors have to be a compromise of tunability (High Q) and bandwidth... so the bottleneck is in the phasor, the rest of the system being infinitely more tolerant. 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. I don't see how that can be improved. Series feeding the tower will require a fairly high Q network that is inherently narrow band compared to a shunt feed method. The kind of network and the network design can make a pretty decent broadbanding within licensed bandwith possible. In any case, you are not going to get a shunt fed tower in the US, and you are not going to get shunt fed directionals anywhere. 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. I don't see where you keep on this tack about Unipoles as they can just as easily be part of a directional network. Shunt fed towers tend to have slight directionality, and unipoles have enormous mechanical instability, making adjusting a unipole directional and meeting licensing requirements something that might not even be possible. And the cost of readjusting as the outriggers move about and the wires strech and age would be huge... most station engineers do not adjust their own directionals... a consulting engineer does, at great cost. I don't see where a Unipole would present a problem in a directional network. See above. Mechanical stability is the first issue. 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. That's fine if the coax and transmitter output impedance is 52 ohms. I didn't realize I was making it more complicated I was just trying to explain the dynamics of tuning the tower. How many towers have you tuned? An ATU is usually necessary. Always unless there is a perfect match. I chatted with some engineers who are into this sort of thing, and we came up with one station in the west, the 1590 in the Victor Valley about two decades ago... it has since moved and has a doghouse at the tower base, now. 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. Wow, I guess the engineering of the IBOC working group really sucks. I figured something in the way of the application in the field is what would bring things down. This is far worse that I imagined. iBiquity does not design exciters. In this case, the HD exciter was built by one of the big three transmitter companies, and it had a "design mismatch" (read "flaw") when mated to one particular transmitter which they did not even manufacture. It's the price stations pay for being early on the curve... which is usual in major markets because, problem and all, such stations have at least one backup transmitter, and many have two. Or, in today's transmitters, it does neither. It detects VSWR and shuts off. And all my equipment has fuses or circuit breakers but I usually apply effort toward making sure they are not used. In the case of transmitters, the control circuit performs system shutdown or power reduction to protect itself without fuses or circuit breakers; a high VSWR might cause a transmitter to progressively fall back to half power, half again, and so on until it can operate... or it shuts off. 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 ... read more »- Hide quoted text - - Show quoted text - Of course, none of this justifies your lying about your academic background. |
CBS' KFWB shuts off IBOC at night
"Telamon" wrote in message ... In article , "Brenda Ann" 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. I've been in on installing one of those kits.. lot of fun when you have the backup tower for the station only a few dozens of yards away.. you don't want to forget to connect that ground in at least two places on the way down the tower.. :) That's great. Tell us how it works out when you tune it up. In about 1989, we put a unipole on WDSR 1340 in Lake City, FL. The tower was actually over 90 degrees, but the base was nearly 100 feet offshore in the lake (thus the city name). The brackish water had pretty much dissolved the ground system after some 40 years, and we put down a large ground mesh in the water around the tower, and put a unipole on. The folks form Tennessee came down, and they supervised the rigger. they strapped the tower base plate to ground with three 2" copper straps, and use experience, the known impedance of the tower and the rigger to find a connect point. They were close enough that only two minor moves of less than a meter fund the right match, and the station was back on the air. The unipole did increase coverage, in an area where ground conductivity is horrible. We did not notice any audio change, good or bad. The only long term bad thing is that the outriggers had to be retensioned a bit, and in major storms flying objects could break the wires or dislodge the fiberglass yardarms that held them away from the tower, and on one occasion breaking the critters off at the tower mount. I would not want one in a hurricane prone region, as it would fly off the tower at the first impact of airborne aluminum siding or trash cans. |
CBS' KFWB shuts off IBOC at night
"Steve" wrote in message oups.com... Of course, none of this justifies your lying about your academic background. It's obviously past your bedtime. But, before you go, there is a Boise 50 kw AM on Craigslist for $800 thousand dollars... why don't you buy it and impress us all with your radio talent and knowledge? Of course, the potty words you erupt with here will have to be controlled, perhaps with a muzzle. |
CBS' KFWB shuts off IBOC at night
"Telamon" wrote in message ... I don't see the need to be so defensive about what I posted. I made it clear it was an assumption and explained my logic for those assumptions. The reasoning was technical and there is no need to try to make it into something else. By the way, thank you for an interesting and civil discussion. Your technical knowledge is obviously extensive, and some of my anecdotal or field experience may be unknown to you. Goes to show... we can learn from each other. I hope... |
CBS' KFWB shuts off IBOC at night
"Telamon" wrote in message ... In article , "Brenda Ann" 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. I've been in on installing one of those kits.. lot of fun when you have the backup tower for the station only a few dozens of yards away.. you don't want to forget to connect that ground in at least two places on the way down the tower.. :) That's great. Tell us how it works out when you tune it up. This has been about 8 years or so ago now, at the 970 AM site in Portland, OR. We didn't do the tuneup, that was left for their CE to do. We did the tower work. I've had the opportunity (mostly doing grunt work) to work around lots of high energy RF. I had the really fun job of resplicing all the ground wires at the former Sunny 1520 (also a Portland market station) during a new site install. We built the new transmitter shack (moving the 50KW box out of the back room of a preschool of all places). I got to, as I said, reattach all the radials, about 300 of them, on a 3 tower system, then, when the concrete and block work were done (in different stages) I had to lay expanded copper mesh on the foundation, walls and roof of the shack (Faraday cage). Then I ran a few thousand feet of 50 pair icky-pick for control wiring. All this fun in August. :) Sure loved the $$$ though.. |
CBS' KFWB shuts off IBOC at night
David Eduardo wrote: "dxAce" wrote in message ... David Eduardo wrote: "dxAce" wrote in message ... David Eduardo wrote: 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? The authorization, which was not a license certificate, but an "oficio" was in '66 or '67. Guess that's why it never shows up anywhere! "oficio" must mean "faux". An "oficio" is basically an "edict" and is a folio with fiscal stamps and a notification text. Gee! |
CBS' KFWB shuts off IBOC at night
David Eduardo wrote: "dxAce" wrote in message ... David Eduardo wrote: "Steve" wrote in message ups.com... On Oct 10, 2:27 pm, dxAce wrote: 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. The 1974 license on my website is a RENEWAL. NOT! Since I was chief operator of WUNO from late '70 to mid-'72, and that requires not only a 1st ticket but notification of the Engineer in Charge of the FCC field office, there is, no doubt, somewhere record of it. So you 'claim'! Was your legal name, "David Frackelton Gleason", on that forgery as well? |
CBS' KFWB shuts off IBOC at night
On Oct 10, 11:31 pm, "David Eduardo" wrote:
"Steve" wrote in message oups.com... Of course, none of this justifies your lying about your academic background. It's obviously past your bedtime. But, before you go, there is a Boise 50 kw AM on Craigslist for $800 thousand dollars... why don't you buy it and impress us all with your radio talent and knowledge? Of course, the potty words you erupt with here will have to be controlled, perhaps with a muzzle. You're much closer to Boise than I am. Why don't you buy it? Perhaps you can solve all of it's problems by putting a fresh coat of paint on the station. |
CBS' KFWB shuts off IBOC at night
On Oct 10, 11:33 pm, "David Eduardo" wrote:
"Telamon" wrote in message ... I don't see the need to be so defensive about what I posted. I made it clear it was an assumption and explained my logic for those assumptions. The reasoning was technical and there is no need to try to make it into something else. By the way, thank you for an interesting and civil discussion. Your technical knowledge is obviously extensive, and some of my anecdotal or field experience may be unknown to you. Goes to show... we can learn from each other. I hope... I'll bet you could also learn from on-topic posts. You might want to give it a shot. Maybe start off slow, with one or two on-topic posts, and see how it goes. |
CBS' KFWB shuts off IBOC at night
On Oct 10, 11:33 pm, "David Eduardo" wrote:
"Telamon" wrote in message ... I don't see the need to be so defensive about what I posted. I made it clear it was an assumption and explained my logic for those assumptions. The reasoning was technical and there is no need to try to make it into something else. By the way, thank you for an interesting and civil discussion. Your technical knowledge is obviously extensive, and some of my anecdotal or field experience may be unknown to you. Goes to show... we can learn from each other. I hope... Let's all join hands now and sing "We Are The World"... |
CBS' KFWB shuts off IBOC at night
On Wed, 10 Oct 2007 06:41:56 -0700, "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. The 10 kHz heterodynes are from the carriers, not the sidebands. They can easily be notched out, by the way. |
CBS' KFWB shuts off IBOC at night
On Thu, 11 Oct 2007 01:53:51 GMT, Telamon
wrote: In article , "Brenda Ann" 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. I've been in on installing one of those kits.. lot of fun when you have the backup tower for the station only a few dozens of yards away.. you don't want to forget to connect that ground in at least two places on the way down the tower.. :) That's great. Tell us how it works out when you tune it up. There's a couple of mountain top AMs in Santa Barbara that use folded unipole. |
CBS' KFWB shuts off IBOC at night
In article ,
"David Eduardo" wrote: "Telamon" wrote in message ... In article , "David Eduardo" wrote: 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? They would not and since when is Idaho, Wisconsin, Arizona or Alabama in south America? I asked why South or Central America would have conditions of terrain, grounding or cost any different than those states? I have no idea why you think a unipole would be of any greater advantage there than in, say, Lake City, FL? Why? In a simple sentence; why would grounding be different than in the US. Another: why would the terrain be different than in the US? The pacific side of central America is similar to Florida but not the west or south America. I don't understand why you are keying on central or south America. I don't know why grounded towers are not used in most place most of the time. 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. Where did I say it was more expensive in SA? You said that Latin America is "where (it is) expensive to install..." And I do not see that it is expensive at all, and where a unipole would be less expensive. Ground systems are expensive to install. The grounded towers don't eliminate them they just make them less critical. The logic is why spend money you don't have to spend. The problem looks to be reading comprehension. Importing a unipole kit from the US (nobody makes them or uses them in Latin America) and bringing in an experiienced installer would be much more expensive than a simple to build and maintain series fed antenna. Every nation in Latin America has a local tower fabricator and erector or two. I don't understand where you are going with this. A grounded tower does not eliminate the ground system it just makes for an easier to tune and more broad band antenna. The antenna is easier to load properly. 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. No. You obviously have not measured may, if any, AM vertical radiators. Untill they get very wide, like the old towers of the 20's and 30's which were built like scaffolding, there is no appreciale benefit in width, and the cost at any optimum point is prohibitative and likely will get no zoning clearance. The problem with bandwidth can be solved by ATU design, and VSWR reduced to less than 1.09 to 1 at 10 kHz with ease. I haven't tuned any AM broadcasting towers but I have tuned higher frequency antennas and I know theory and there are companies that build kits I described to broaden the towers bandwidth as I described. So for you to be right the theory as I understand it is wrong, I didn't understand what was really happening in my past antenna tuning experience and there are companies out there selling radio stations crap for antenna modification kits. So that said where do you think things went wrong? 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. I don't have that book so I can't do that but general theory would indicate otherwise and there are companies that offer tower kits to improve bandwidth performance as I have described. The purpose of a unipole is to allow the tower to be at ground potential so we can get point to point and other antenna rentals without isocouplers. It is also to compensate for bad grounds, like where a parking lot and shopping center now sit on the ground system. Bandwidth is mostly enhanced below 1/4 wave, and the FCC only licences such towers under extreme circumstances... very few towers under 90 degrees exist in the US. I've seen a bunch of non-licensed stations, such as AFRTS facilities using them though.... 1040 at Ft. Brook used one to tune a roughly 75 foot tower and it did not sound too dreadful, either. Rame, on 780, used one on a 50 foot tower, also. The purpose you state may your reason to use a ground tower. 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. Again that is not my understanding of tower VSWR. The levels at 5, 10, and 15 KHz are much higher than you indicate, which requires mitigation efforts. The ATU will generally create a 52 ohm match at carrier, and j 0. At plus or minus 10 kHz, we would look for well under 1.1 to 1 VSWR with a good ATU. They can be designed to give even less than that, but considering the amount of entergy under NRSC at 10 kHz is minimal, that is often good enough. The ATU can not improve the tower bandwidth. The ATU can only make it worse. 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. For analog +/- 10 KHz sounds reasonable but it looks like IBOC is going past that number. The testing recommendation I read suggests testing to +/- 15 KHz. The stations for which AM HD is even appropriate are major stations in each market only... and most of these have nicely designed antennas. The very directional stations are going to have more problems in the phasor than in the ATU and tower. Phasors have to be a compromise of tunability (High Q) and bandwidth... so the bottleneck is in the phasor, the rest of the system being infinitely more tolerant. 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. I don't see how that can be improved. Series feeding the tower will require a fairly high Q network that is inherently narrow band compared to a shunt feed method. The kind of network and the network design can make a pretty decent broadbanding within licensed bandwith possible. In any case, you are not going to get a shunt fed tower in the US, and you are not going to get shunt fed directionals anywhere. The ATU's and antenna networks do not improve antenna bandwidth. 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. I don't see where you keep on this tack about Unipoles as they can just as easily be part of a directional network. Shunt fed towers tend to have slight directionality, and unipoles have enormous mechanical instability, making adjusting a unipole directional and meeting licensing requirements something that might not even be possible. And the cost of readjusting as the outriggers move about and the wires strech and age would be huge... most station engineers do not adjust their own directionals... a consulting engineer does, at great cost. I don't see where a Unipole would present a problem in a directional network. See above. Mechanical stability is the first issue. 1. I was posting about grounded towers not Uniploes. 2. Grounded tower are more stable that isolated ones. 3. I don't where a Unipole would be more of a mechanical design problem over an isolated 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. That's fine if the coax and transmitter output impedance is 52 ohms. I didn't realize I was making it more complicated I was just trying to explain the dynamics of tuning the tower. How many towers have you tuned? AM broadcast towers zero. I have tuned many other types of antennas and RF circuits. AM towers tune like any other antenna of its type. An ATU is usually necessary. Always unless there is a perfect match. I chatted with some engineers who are into this sort of thing, and we came up with one station in the west, the 1590 in the Victor Valley about two decades ago... it has since moved and has a doghouse at the tower base, now. Many amateur radio operators don't understand the necessity of tuning the antenna at the antenna and not in the shack. Usually this is done for convenience though. 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. Wow, I guess the engineering of the IBOC working group really sucks. I figured something in the way of the application in the field is what would bring things down. This is far worse that I imagined. iBiquity does not design exciters. In this case, the HD exciter was built by one of the big three transmitter companies, and it had a "design mismatch" (read "flaw") when mated to one particular transmitter which they did not even manufacture. It's the price stations pay for being early on the curve... which is usual in major markets because, problem and all, such stations have at least one backup transmitter, and many have two. Or, in today's transmitters, it does neither. It detects VSWR and shuts off. And all my equipment has fuses or circuit breakers but I usually apply effort toward making sure they are not used. In the case of transmitters, the control circuit performs system shutdown or power reduction to protect itself without fuses or circuit breakers; a high VSWR might cause a transmitter to progressively fall back to half power, half again, and so on until it can operate... or it shuts off. You may be looking at this a little to simplistically. I don't know what the response time of the transmitter fallback circuitry is and I don't know when the transmitter modules failed. Did they fail at the turn on of the IBOC exciter? Did they fail after a while? I don't know the details. 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. I don't see the need to be so defensive about what I posted. I made it clear it was an assumption and explained my logic for those assumptions. The reasoning was technical and there is no need to try to make it into something else. In that case, I do apologize. I may have mistakenly thought you were one of the multitude that thinks that all of Latin America consists of terrain that can only be found in an Indiana Jones movie; the fact is that the land anywhere there is comparable to some place in the US. Towers tend to cost less, as they are locally fabricated and the labor costs are lower; ATUs and such can be made from off the shelf caps and coils you can wind from automotive AC tubing if the need arises. From what I have seen the coils don't look to hard to fabricate out of tubing but you have to buy the high voltage vacuum capacitors. The connections look like hardware store nuts and bolts would do most of the time. You would most likely need to buy sense transformers for the metering. -- Telamon Ventura, California |
CBS' KFWB shuts off IBOC at night
In article ,
"David Eduardo" wrote: "Telamon" wrote in message ... In article , "Brenda Ann" 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. I've been in on installing one of those kits.. lot of fun when you have the backup tower for the station only a few dozens of yards away.. you don't want to forget to connect that ground in at least two places on the way down the tower.. :) That's great. Tell us how it works out when you tune it up. In about 1989, we put a unipole on WDSR 1340 in Lake City, FL. The tower was actually over 90 degrees, but the base was nearly 100 feet offshore in the lake (thus the city name). The brackish water had pretty much dissolved the ground system after some 40 years, and we put down a large ground mesh in the water around the tower, and put a unipole on. The folks form Tennessee came down, and they supervised the rigger. they strapped the tower base plate to ground with three 2" copper straps, and use experience, the known impedance of the tower and the rigger to find a connect point. They were close enough that only two minor moves of less than a meter fund the right match, and the station was back on the air. The unipole did increase coverage, in an area where ground conductivity is horrible. We did not notice any audio change, good or bad. The only long term bad thing is that the outriggers had to be retensioned a bit, and in major storms flying objects could break the wires or dislodge the fiberglass yardarms that held them away from the tower, and on one occasion breaking the critters off at the tower mount. I would not want one in a hurricane prone region, as it would fly off the tower at the first impact of airborne aluminum siding or trash cans. That's a good point. I didn't think about flying objects breaking the tower wires on the extenders. Every engineering solution has its down side. -- Telamon Ventura, California |
CBS' KFWB shuts off IBOC at night
"Telamon" wrote in message ... In a simple sentence; why would grounding be different than in the US. Another: why would the terrain be different than in the US? The pacific side of central America is similar to Florida but not the west or south America. I don't understand why you are keying on central or south America. I don't know why grounded towers are not used in most place most of the time. The Pacific side of Central America consists of a variety of terrain. It is soft loamy soil in most places, with mountains farther inland. The conductivity is high, and it is like the gulf coast of Texas for the most part, as is the Caribbean coast... although that is more tropical rain forrest like, with lower conductivity. In both places, the soil is easy to plow, and it is simple to put in a ground. Unipoles are costly, have to be imported in kit form, and are often not built to fit locally built metric dimensioned towers. In addition, few broadcast engineers know the system. Finally, unipoles, as proven in Puerto Rico and Florida, do not hold up well in hurricane territory. South America has as much variety of land as the continental US does. Most medium and smaller AMs use shorter towers... I had below quarter wave on all but two of mine in Ecuador due to costs; when I built my first tower in 1964 the only other station with a tower was the government station and the one owned by the two daily newspapers... it was hard to find a crew to rig it and all the sections, then, were imported. With spots at less than a dime at the time, importing anything was a luxury we could not afford. Other stations used longwires between phone poles.... all 40 of them. You said that Latin America is "where (it is) expensive to install..." And I do not see that it is expensive at all, and where a unipole would be less expensive. Ground systems are expensive to install. The grounded towers don't eliminate them they just make them less critical. Grounds in Latin America, where much of our copper comes from, are dirt cheap. Labor is typically a tenth or less of US costs, the society is not as litigious, so there is no need for insurance, and it is generally very cheap and low tech. I don't understand where you are going with this. A grounded tower does not eliminate the ground system it just makes for an easier to tune and more broad band antenna. The antenna is easier to load properly. Unipoles, like shunt fed towers, are hard to tune. That is why in the US the kits are also accompanied by a visit from a trained engineer who knows how to find the right feed point. While a station engineer can easily tune a series fed tower with simple principles using an OIB, a shunt fed system like a unipole, requires special riggers and special tuning techniques. and is very susceptible to damage in high wind zones. The broadband aspect is not at all of interest, since almost 100% of Latin American AMs (save a few in Mexico and one or two athat are intentionally directional do cover better the market, not for protection) are single towers, and single towers can easily be tuned to decent characteristics, there is no need for broadbanding and never was one. You obviously have not measured may, if any, AM vertical radiators. Untill they get very wide, like the old towers of the 20's and 30's which were built like scaffolding, there is no appreciale benefit in width, and the cost at any optimum point is prohibitative and likely will get no zoning clearance. The problem with bandwidth can be solved by ATU design, and VSWR reduced to less than 1.09 to 1 at 10 kHz with ease. I haven't tuned any AM broadcasting towers but I have tuned higher frequency antennas and I know theory and there are companies that build kits I described to broaden the towers bandwidth as I described. If you read the websites, like the Kintronics one, you will see the principal point of purchase is for bad grounds and to enable renting tower space to other customers. It's so hard today to get a tower built, and smaller market radio is such a poor business that the revenue from tower rental is a very important item in most places. Very few single tower AMs are really worried about andwidth a they are so easy to tune with easy to adjust ATU's. As metioned, the cost of importing (duties of as much as 100% and huge shipping costs) plus the cost of bringing in a specialized antenna is way too much for the perception of minimal gains. So for you to be right the theory as I understand it is wrong, I didn't understand what was really happening in my past antenna tuning experience and there are companies out there selling radio stations crap for antenna modification kits. I did not say that. The unipole is 90% of interst for enabling existing towers to be used for other purposes without isocouplers. The remaining 10% is for situations where the ground system is deteriorated and difficult to replace, or the station is on a rooftop and uses a conutnerpise ground, etc. The slight, and barely perceptable bandwidth issue is a tiny sidebar benefirt... the added bandwith on any tower in use in the US is so minimal compared to a well tuned series fed tower that this can not alone justify the change from a standard series fed tower; the time off air is also a major consideration. The purpose of a unipole is to allow the tower to be at ground potential so we can get point to point and other antenna rentals without isocouplers. It is also to compensate for bad grounds, like where a parking lot and shopping center now sit on the ground system. Bandwidth is mostly enhanced below 1/4 wave, and the FCC only licences such towers under extreme circumstances... very few towers under 90 degrees exist in the US. I've seen a bunch of non-licensed stations, such as AFRTS facilities using them though.... 1040 at Ft. Brook used one to tune a roughly 75 foot tower and it did not sound too dreadful, either. Rame, on 780, used one on a 50 foot tower, also. The purpose you state may your reason to use a ground tower. But those are not licensed stations... they are AFRTS staitons on military bases. US and Latin American commercial stations do not use unipoles commonly or, in the later case, at all. The ATU will generally create a 52 ohm match at carrier, and j 0. At plus or minus 10 kHz, we would look for well under 1.1 to 1 VSWR with a good ATU. They can be designed to give even less than that, but considering the amount of entergy under NRSC at 10 kHz is minimal, that is often good enough. The ATU can not improve the tower bandwidth. The ATU can only make it worse. And tower bandwidth at quarter wave and above is adequate for the AM service. An ATU can take a short tower, using one example of 60 meters high at 570 AM, that measures 11 ohms -j 110 and make it 52 ohms at carrier, with only +/- 5 ohms at 10 khz and similarly tolerable reactance... and pretty decent bandwidth that can be compensated for by a minor amount of equalization. There is no need to go off the air for days to install and tune a unipole if there is no perception of gain. In any case, AM is dying in Latin America much faster than in the US, with many nations like Chile and Ecuador and most of Central America having fewer stations today than 10 years ago, so any unnecessary investment would be rejected. .. The kind of network and the network design can make a pretty decent broadbanding within licensed bandwith possible. In any case, you are not going to get a shunt fed tower in the US, and you are not going to get shunt fed directionals anywhere. The ATU's and antenna networks do not improve antenna bandwidth. The only place where bandwidth within the NRSC mask is an issue on AMs that are directional. and the towers are generally 5% of the issue while the phasor is 95%. Phasor redesign requres relicencing the directional, and, gnerally, an antenna proof or partial proof... the time may be many months, depending on how much air time the station can afford to lose. 1. I was posting about grounded towers not Uniploes. 2. Grounded tower are more stable that isolated ones. 3. I don't where a Unipole would be more of a mechanical design problem over an isolated tower. Shunt fed towers in the US are not licensed; I don't know if one could even get a waiver to use one. Outside the US, the tuning requires riggers on a live tower, and that is much more complicated than a simple series fed system that does everything for less money. There are few who even know how to find a match point on a shunt fed tower while anyone with an OIB can tune by trial and error a series fed tower. AM broadcast towers zero. I have tuned many other types of antennas and RF circuits. AM towers tune like any other antenna of its type. Due to the wavelengths involved the huge amount of land needed for the ground, etc., AM antennas are rather unique... and when you get to multi-tower directionals, even more so. Doing a full FCC directional proof may take weeks, and adjusting a critical array months. One construction permit, for 10 kw night operation of WISN in Milwaukee, took nearly 2 decades to build and adjust and get tuned to operate legally. You may be looking at this a little to simplistically. I don't know what the response time of the transmitter fallback circuitry is and I don't know when the transmitter modules failed. Did they fail at the turn on of the IBOC exciter? Did they fail after a while? I don't know the details. No, they failed due to an improper instruction in installation instructions regarding the interface between the transmitter and the HD exciter which, basically, caused the power modules (there are 128 for 50 kw operation) to overdrive and literally burn out. In this case, the problem was not corrected by the fialsafe circuitry as it essentially defeated it rather than interfacing a second system with it. In that case, I do apologize. I may have mistakenly thought you were one of the multitude that thinks that all of Latin America consists of terrain that can only be found in an Indiana Jones movie; the fact is that the land anywhere there is comparable to some place in the US. Towers tend to cost less, as they are locally fabricated and the labor costs are lower; ATUs and such can be made from off the shelf caps and coils you can wind from automotive AC tubing if the need arises. From what I have seen the coils don't look to hard to fabricate out of tubing but you have to buy the high voltage vacuum capacitors. The connections look like hardware store nuts and bolts would do most of the time. You would most likely need to buy sense transformers for the metering. Most metering today is an RF ammeter at the doghouse and, for directional stations, an RF sampling system which allows phase and current to be detected for each tower. Neither is very expensive. With pretty simple components, even things like diplexers can be built, too. Remember that most directionals and even ATUs in use in the US were built before computers could assist in the design. The diplexer shown on my website, built in 1966, was entirely calculated and designed using a slide rule and a notepad... this is one of the reasons why highQ networks were preferred as they were easy to design and tune in the field. |
CBS' KFWB shuts off IBOC at night
"Telamon" wrote in message ... That's a good point. I didn't think about flying objects breaking the tower wires on the extenders. Every engineering solution has its down side. Then you will appreciate this: after one of the major gulf coast hurricanes, in the 70's, an engineer from Miami was hired to settle some tower destructions. One, which failed at about 80 feet and collapsed was examined. The measurements on the damaged section that caused the failure exactly matched the shape and mass of a cow which had been picked up and hurled into the tower 80 feet over the ground. You can not designee for the occasional flying cow. |
CBS' KFWB shuts off IBOC at night
On Oct 11, 10:41 pm, "David Eduardo" wrote:
"Telamon" wrote in message ... That's a good point. I didn't think about flying objects breaking the tower wires on the extenders. Every engineering solution has its down side. - Then you will appreciate this: after one of the major gulf coast hurricanes, - in the 70's, an engineer from Miami was hired to settle some tower - destructions. One, which failed at about 80 feet and collapsed was examined. - The measurements on the damaged section that caused the failure exactly - matched the shape and mass of a cow which had been picked up and hurled into - the tower 80 feet over the ground. You can not designee for the occasional - flying cow. Gives new meaning to "When Cows {Pigs} Fly" am'er - watch-out for that tower ~ RHF |
CBS' KFWB shuts off IBOC at night
On Oct 12, 1:41 am, "David Eduardo" wrote:
"Telamon" wrote in message ... That's a good point. I didn't think about flying objects breaking the tower wires on the extenders. Every engineering solution has its down side. Then you will appreciate this: after one of the major gulf coast hurricanes, in the 70's, an engineer from Miami was hired to settle some tower destructions. One, which failed at about 80 feet and collapsed was examined. The measurements on the damaged section that caused the failure exactly matched the shape and mass of a cow which had been picked up and hurled into the tower 80 feet over the ground. You can not designee for the occasional flying cow. What have you been listening to on shortwave lately? |
CBS' KFWB shuts off IBOC at night
"Telamon" wrote in message ... Well, thanks for the replies. I learned a few things. It was an interesting discussion. Agreed. Thanks. |
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