Far better than I could ever explain it, Dave Hershberger, of Continental Electronics explains some of the potential problems with increasing the IBOC carrier(s) in an FM HD Radio system. If you have not already read it, read the entire article, it sheds some interesting light on the IBOC system and how it works.
Transmitting more digital power will certainly increase the digital coverage area and reduce digital dropouts. However, there may be some unintended consequences, which every broadcaster will have to evaluate before increasing digital power.
It is all right there. What amazes me is that the IBOC proponents do not acknowledge the system’s problems. Perhaps the above article is a bit over the head of the average general manager, or group VP, whatever the title dejour is. Engineers should understand this. Engineers should be able to explain this in an understandable way to managers and owners. It is the owners or whoever is holding their paper that have the most to loose in this scheme, which is to say, everything. Forget the FCC, they are in the pockets of their corporate sponsors anyway. Radio station owner’s and the bankers that control them should take a real hard look at this and see for themselves that they are writing their own epitaph.
Letter to the editor in the April 15, 1987 Radio World:
I’ve heard all the garbage I can stand about the AM stereo “issue.” The problem?
1. Motorola and Kahn each was a monopoly.
2. The stations don’t want to waste $6,000 on the wrong system.
3. The FCC is afraid it will be sued by the “sore loser” in a standard decision.
4. The receiver makers are afraid of wasting millions of the wrong system.
5. The listeners don’t know anything about AM stereo.
Does any of this sound vaguely familiar regarding some AM “improvement” scheme currently being used? Those that fail to learn from history are destined to repeat it, Bob.
Oh, if only it where so, AM stations would be rich! Rich, I tell you. This dates back to 1987 article in radio world that details how AM stations receiving Cuban interference could submit to the USIA (US Information Agency), the State Department VOA oversight organization, detailed interference reports and requests for reimbursement of lost revenue. In addition to that, the FCC would consider night time power increases and or pattern modifications, so long as no US or Canadian station was adversely effected by the changes.
Prior to about 1980 or so, Cuba adhered to the NARBA of 1950. This allocated broadcast channels in the AM band, including clear channels for the US, Canada, Mexico, Cuba and the Bahamas. Later on, most of the countries in South America joined the treaty and most international interference was mitigated.
Then, for reasons only known to Fidel, Cuba began broadcasting high power on several frequencies. The stations suffering the worst interference were all in Florida; WINZ, Miami, WVCG, Coral Gables, WNWS, South Miami, WEAT, West Palm Beach, WQBA, Miami, WKAT Miami Beach and WSUN, St. Petersburg.
In our neck of the woods, WICC suffered some pretty bad interference from CMKA on 600 kHz. According to treaty, CMKA was supposed to transmit with no greater than 2.5 KW. Sometime in early 1981, they increased power to 150 KW. The path between WICC and CMKA’s transmitter site is almost entirely over salt water. Additionally, CMKA utilizes a fairly tall tower, 130 degrees according to the FCC data base.
The interference was worst in last fall and early spring. Several local newspaper articles were were written about the subject, noting that WICC developed a contest around the interference. The station would drop it’s carrier for 10 seconds at 6:30 and 7:10 pm. Listeners would then try to identify the Cuban songs playing on CMKA and drop a post card to WICC with that information. Winners were picked randomly from the all the correct answers received (CMKA would also be heard on the studio air monitor). Coincidentally, after several months of this, the Cuban station switched it’s programming to English.
In any case, I believe the USIA paid out a total of $500 K to the Florida stations.
The NAB (National Association of Broadcasters), in trying to reach a settlement with the music industry, has decided that cellphones are part of the problem. No kidding, the fact that smart phones like the iPhone and Android do not have FM tuners seems to be a part of the negotiations, even though the cellphone industry has nothing to do with music royalties. The argument is, more people will listen to, and more importantly, buy music if they have an FM tuner in their smartphone.
I don’t know about that.
My HTC Android phone does have an FM tuner, it also has a metal detector. I have found both the be novel applications. Even though I work in radio, I have used the FM tuner twice. Technically speaking, I find it to be adequate. In order to receive anything, a pair of headphones or earbuds has to be used, because the headphone wire acts as the antenna.
That being said, I cannot count the number of times I have used Pandora or other online audio applications. Several times a day at least. Why? Because the content it better.
If consumers want FM tuners in their cellphones, they will ask for them. Cellphone manufacture’s will gladly comply, and make them. The real problem is, most people don’t care about radio because most radio programming is boring and uninspired these days. Let me paraphrase that:
HELLO, BROADCASTERS! ARE YOU LISTENING? YOUR PROGRAMMING SUCKS!
Offer a better product and listeners will return. If there were a compelling reason to build FM tuners into cellphones, it would already be done. Forcing the cellphone manufactures to do something they don’t want to do will simply drive up prices.
The NAB has led the radio industry astray for years now, we really should stop listening to them.
One day, for no good reason, the DA (Directional Antenna) which had previously been rock stable goes haywire. WHAT THE! The phase is way out, or the current ratio is jumping around, nothing makes sense! Time to start cranking on those phasor handles! NOT! AM DA’s are pretty easy to work on, once you get past all the smoke and mirrors hokus pokus stuff.
The first rule of trouble shooting is cause and effect. Every DA has a common point, which is where the input impedance and transmitter power is measured. The common point is the sum of all the tower impedances as seen through the power divider. Any significant changes to the DA will cause the common point current to shift, either up or down.
What does the transmitter say? Most solid state transmitters do not like to run into loads that are significantly departed from 50Ω j0. If the common point has changed, so has the impedance and the transmitter is likely folding back to protect it’s MOSFETS. Tube transmitters are more tolerant, but other signs may exist like increased or decreased modulation levels.
What do the tower base currents say? An AM DA licenses will specify base current ratios as related to the reference tower. That is to say, take the base current of a tower and divide it by the reference tower base current. Those should be within 2% of the licensed value
What do the monitor points say? Every AM DA will have monitor points for each pattern. The maximum values will be specified on the license. In addition to that, a good station practice is to do monitor point readings several times a year and keep a log. Anything out of the ordinary indicates a problem with the DA.
1. Problem: Phase and or current ratios are out on one or more towers. All else is normal. In this case, normal operation of a DA can be confirmed by base current ratios and monitor points. Both those values should be on the license. If base currents and monitor points are normal, then this is most certainly a sample system problem. Most sample systems have either a sample loop on the tower or a toroid current transformer at the base. Working from the tower back to the antenna monitor, use a Simpson 260 VOM to check for continuity. Use a working tower get baseline information, e.g. the sample loop is a DC short, the toroid has 4 ohms DC resistance, etc. Be careful of working in hot ATU’s.
2. Problem: All current/phase rations are out of tolerance and the reflected power on the transmitter has gone up. This would indicate that a change has occurred with one of the tower impedances. Look for changes at the base tower, excessive vegetation, flooding, burned, shorted or open components can cause this. Be sure to check things like sample system and tower light isolation coils.
3. Problem: Common point current has changed one tower current/phase ration is out of tolerance. Many AM arrays have a tower that actually present a negative impedance to the phasor. In this case, the power is “absorbed” from the tower and fed back to the phasor. Check the tower base current of the out of tolerance tower. Often times, something has occurred to take that tower out of the circuit.
4. Problem: All or some of the readings are slightly out of tolerance. Not enough to indicate a real issue, more like a slow drifting over time. This can be caused by seasonal variations. Depending on the wavelength of the tower, tower bases can be very sensitive to small changes in ground conductivity, just as increased or decreased soil moisture.
5. Problem: 2 pattern station, on pattern works, the other does not. This is a phasor control issue. Most DA2 stations rely on contact closures at the tower base to ensure that the pattern switching contactors have moved into the correct position. Often times, a contactor will be hung up or a micro switch will be bad. Another possibility is a hung up contactor in the phasor, or a control circuit problem.
Those are general starting points. Often times, evaluating all of the information on hand will shed some light on the issue. AM DA’s will have the following operating indicating systems:
Transmitter directional coupler and overload circuits
Directional Antenna system monitoring system
Tower base current meters
Monitoring points
Phasor indicator lights
Building all of those indicators into one picture will generally point to the problem. When trouble shooting begin at one end of the circuit and logically work your way to the other.
Sometimes some seasonal effect will cause the readings to be off. Before any phasor handle is turned, make a note of all the readings on the dial cranks. This way, if things get out of whack there is a restore point. If there is a seasonal variation with the antenna array, it should be well documented by previous seasons pattern changes. If not, it could be a slow deterioration of the ground system or ATU components.
If a person were to drive south down I-95 through Bridgeport, CT and look off to the left, they would see a 500 foot smokestack for a coal fired power plant. Side mounted on that smokestack is a 6 bay Shively FM antenna. The antenna is more visible when driving south. That would be the antenna for WEBE 107.9 Mhz. This is right down town, therefore, I would imagine this station has no problems with reception.
Bridgeport Power Plant smokestack, viewed from the west
WEBE is a class B FM with a full 50 KW ERP. Most FM’s around here take advantage of a nearby mountain to gain some altitude and thus reduce the TPO a bit. There are several class B stations that run less than 5 KW into a relatively small antenna, but they are way up in the 900 to 1000 foot HAAT range. In this case, the power plant is located right on the Pequonnock River bay, so the AMSL at the base of the smokestack is only 10 feet. This means lots of watts out and a fairly large antenna.
They are using Broadcast Electronics FM35A for the main and backup transmitters. They were installed in late 1986 and are a little long in the tooth.
Broadcast Electronics FM35A transmitter
They run near 12 KV plate supply, about 3.8 amps making 34 KW TPO. That goes into a six bay Shively 6 bay 6813 antenna centered at 475 feet, which makes the HAAT 117 meters.
One of the problems encountered with at site is the smokestack emissions. It seems that a fair amount of mercury comes out to the top of that thing. In the past, this has caused major problems with the antenna shorting itself out and burning up transmission line. Because of this, the entire antenna system, radomes, and transmission line is supplied with Nitrogen from this liquid nitrogen tank:
Liquid Nitrogen Tank
The antenna then intentionally bleeds N2 into the radomes continuously, overpressurizing them, to keep the smokestack emissions out. This type of tank is needed because a conventional N2 tank would last about a day, whereas the liquid tank lasts about 20 days.
The BE FM35A decided to blow a 200 Amp fuse on Friday afternoon:
Blown 200 Amp fuse
I had a BE FM30A that would randomly trip the 200 amp main breaker every once in a while. I could never find anything wrong with the transmitter, it would just come back on and run normally again after the breaker was reset. I even replaced the breaker thinking breaker fatigue. Still happened. In the end, we replaced that transmitter. In this case, I don’t see that happening anytime soon.
BE FM35A heavy iron:
Broadcast Electronics FM35A plate transformer
I would not want to replace this thing, it must easily weight 1,000 pounds.
And rectifier stacks:
Broadcast Electronics FM35A rectifier stacks
12,000 volts DC. That will light up any dirt, dust, piece of fuzz, etc. in the transmitter.
It is one of the more unique FM transmitter sites I’ve ever been to. Every time I see it, I am reminded of that song, Smokestack Lightning. My favorite version of that song is the live recording by the Yardbirds
When I was a wee young lad, the local FM station in town did something called an “Album Side” every Wednesday night at 8 pm. It was a great way to hear half of an album before plunking down five hard earned dollars at the record store. It was also a way to sometimes get a recording of half of the songs on the album using the trusty stereo cassette deck.
Technics SL-1200 Turntabe
By way of these unauthorized recordings, I accumulated a bunch of cassette tapes that had bands like Aerosmith on one side and Foreigner on the other. Often, the last 8-10 minutes of a cassette tape side would be silent. This, coupled with the auto reverse mechanism on the cassette deck often lead to confusion with my high school sweet heart… the music ends, then while we were otherwise distracted and several minutes later, the music begins again at high volume.
I grew up in much simpler times than these.
In any case, the advent of the CD pretty much ruined the concept of album sides. It means much less to somebody to have a show where one would play “half the songs on a CD, one after another, without commercials or liners.” When CD’s became the norm for music playback somewhere in the late 1980′s early 1990′s so went the album side. These days, with computers, MP3′s and all the other music storage mediums, most people wouldn’t even know what an album side was. The shame of it is, it was a great selling tool for the record industry. Even though I owned those bootleg cassette tapes, later on, I went out and bought almost all of the albums that I had illegally recorded off of the radio. To get the other side.
I mentioned this briefly in my last post, many radio engineers have difficulty parting with things. It comes from being the poor stepchild in the radio station hierarchy. Many times I have loped off an XLR connector thinking: Man, a new Neutrix XLR connector is $4.00, I’ll save this one so I won’t have to genuflect as deeply in front of the owner at the station Christmas party this year. Another one: If I save $100.00 on connectors, perhaps the corporate overlords will grant me my $65K studio project. It is sort of silly, no matter how one looks at it.
The other thing that often occurs is retention of old equipment. It makes some sense to hold onto things that may be used again. Back when we first started installing computer automation systems, I kept the cart machines around for a while, just in case. That old Denon 951 CD player, hey those things were expensive. Otari MX5050B, those were really expensive. It seems almost unfathomable that they are now scrap, although having a working reel to reel machine somewhere in house makes sense. You never know when you might need to grab something from the tape archive.
One thing that I never understood was saving bad parts. Once, when I was trying to repair a BE FM30A transmitter, I thought there was a whole shelf of spares. As I picked up each part to look at it, the letters NG, NFG, or BAD were written it with a sharpie. If one is going to take the trouble to write NFG on something, why not just through it away? Which brings me to this:
Speaks for itself
Found in the parts closet at WEBE/WICC in Bridgeport. WEBE and WICC are going through a major clean up/clean out due to a tornado that struck the building on June 24th. The storm ripped the 15 ton HVAC unit off of the roof, damaged the roof membrane and cause major leaks into the studio space. The company I work for was hired to clean up the engineering space so the water damaged carpet and ceiling tiles can be replaced.
The ITC Delta series cart machines were tanks. Once upon a time, Papst Motoren, GmbH would take those bad motors back and rebuild them. They were expensive motors. All of that being said, ITC has been out of business since 1998 and those times have long past.
Storage space is a luxury item. Keeping equipment for studio spares is a good thing. Equipment that is still valuable, but not usable at that location should be sold or traded. Old equipment that no longer has any use or value should be pitched or recycled. Unless something is a collectors item, or belongs in a museum, throw it out, for Pete’s sake.
The company I work for is in the midst of cleaning out a studio location. Most radio engineers are some form of pack rat. I know I have been guilty of this myself, not wanting to throw something away because tomorrow, it might be needed. That was carried out to the extreme at this location. One of the things that I found in my clean out was a Western Electric 212E vacuum tube.
Western Electric 212E vacuum tube
It is an impressive thing, measures about 12 1/2 inches tall, including the pins. I am thinking this is pretty old, it probably came from a pre-WWII Western Electric AM transmitter. This would make the most sense, as the station signed on in 1926 with 250 watts. Back in the day, Western Electric was the patent holder for AM technology. In fact, there was some talk of suing General Electric for patent infringement after the airing of the world series by WJZ and WGY in 1922. Parent company AT&T was working on radio modulation techniques to implement with their telephone system.
These tubes were used for audio amplification, according to the spec sheet, the plate could dissipate 275 watts. Filament voltages is 14 volts at 6.2 amps, the plate voltage was 3,000 volts, maximum. It is a tetrode. The RF counterpart to this tube is the WE 308A.
From what I am to understand, these have not been made since 1960 or so. I also understand there there is quite a cult following for this tube amongst Asian audiophiles. There are several examples of extremely low distortion class A and AB amplifiers using this tube type. Some prices on Ebay are in the $1,500 to $2,000 per tube range. Unfortunately, I don’t think this one works anymore as there is a loose screw and little bits of what looks like control grid wire in the bottom of it. It does light up with 12 volts on the filament, however.
In a way that never ceases to amaze me, Bob Strubel spins another yarn about HD Radio.™ According to Bob:
Tom’s experiences at the Ford dealership are disappointing. We believe they reflect the growing pains which often occur when companies launch new technologies. Tom hit the lot as factory installed HD Radio receivers were just launching.
Well, then, I guess that explains that. If I went to a Ford dealership today, I’d find plenty of models with HD radio(s)™ stock, right?
As far as new technology and growing pains, let us pick that apart piece by piece:
IBOC has been in development since 1990 or thereabouts. Not really new technology. Apple’s iPhone and iPad are new technology (2 years and 3 months respectively).
Ford Motor Company has been an HD Radio™ partner since 2007. One would think that all the kinks would be worked out by now.
The IBOC roll out hit a wall around 2008 and hasn’t grown since then, both the AM technology, which appears to be shrinking, and the FM technology, which appears to be subsidized by the US government.
To test Mr. Strubel’s next statement:
Had he been able to hold out with his old Explorer for another couple months, he would have been able to purchase an Escape with a factory installed HD Radio receiver as these vehicles hit dealerships the first week of August.
It is now the third week in August, I stopped by three Ford dealerships in reasonable sized cities around here. Not really wanting to waste a sales person’s time, I cut to the chase and asked about vehicles with HD radios. Here is the response:
Dealership #1 said they knew about HD radio, but none were in any of their stock vehicles. They also could not give me an idea of how long I’d have to wait to receive one, if ordered separately.
Dealership #2 pointed me in the direction of SiriusXM, saying that satellite radio was digital radio, or HD Radio™ or whatever it was
Dealership #3 never heard of HD Radio™ and said that all their radios were digital (Like, Duh!)
Finally, there is this standard iBiquity statement that seems to go well in any situation:
…it’s ironic that his negative experience happened at a time when the consumer rollout of HD Radio Technology is stronger than it has ever been. We are seeing dramatic receiver sales increases across all segments – OEM auto, consumer electronics, and the new portable HD Radio category. Overall sales of HD Radio receivers will more than double in 2010, and that is on top of a doubling from 2008 to 2009. Can anyone point to any other facet of AM/FM that has seen this sort of growth over the last several years?
Sure, analog AM and FM receivers continue to fly off the shelves in all the markets quoted above too. Furthermore, doubling receiver sales from one small number to another small number is not that dramatic. Like Mark Twain said: “There are three kinds of lies; lies, damned lies and statistics.” It’s like the rookie batting 1000 after his first time at bat; it happens occasionally, it is really not that dramatic or remarkable.
Comparing new technology such as the iPad to middle aged technology such as IBOC is silly. The iPad has all sorts of neat features, interactive programs, applications, etc. IBOC is just a one way radio that does sound any better than the old style radios.
Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.
~1st amendment to the United States Constitution
Any society that would give up a little liberty to gain a little security will deserve neither and lose both.
~Benjamin Franklin
...radio was discovered, and not invented, and that these frequencies and principles were always in existence long before man was aware of them. Therefore, no one owns them. They are there as free as sunlight, which is a higher frequency form of the same energy.
~Alan Weiner
Everyone has the right to freedom of opinion and expression; this right includes the freedom to hold opinions without interference and to seek, receive and impart information and ideas through any media and regardless of frontiers
~Universal Declaration Of Human Rights, Article 19
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