Radio Tower Benchmark Destroyed?

[+Klemmer]

A radio station mast near my office in La Mirada CA was recently brought down completely by a light aircraft . I could almost see it from my office (or just outside it). Unfortunately, two persons in the aircarft were killed. My sympathies to the family. What a tragedy for them. What a time of year for it. I'll say a prayer for them.

 

The radio station mast was also a benchmark (intersection station), which I had previously logged in GC.com as found. I just logged it as destroyed:

DY0566

 

There is a link to one of the local newpaper stories on the benchmark page, and a picture. For GC.com puposes, I'm sure that is OK (i.e. logged as destroyed). What about for NGS purposes? What say the experts monitoring the forum? IS it proof enough for an NGS "destroyed" log? I'm reasonably sure it will be rebuilt there, but who knows? In any case, would it not need to be re-surveyed (if it was worth the expense / effort). Might not be in exactly the same spot (3rd order Horizontal is still pretty accurate). Height and / or description might be different (if it would matter).

 

NGS "destoyed" criteria met?

[caseyb]

Although I was unable to locate the official "what to do when a station is destroyed by a light aircraft" manual I suspect it can be logged as destroyed.

 

I would contact Deb or Cheryl with the info, that way you can include all the "extra" information that you would not be able to include in a normal "recovery".

 

-Casey-

Edited December 20, 2004 by caseyb

[+California Bear]

I would say that a photo of the tower laying on the ground qualifies as proof that the tower is no longer standing. It is going to be odd to go by there and not see the 850+' tower standing there anymore. It could be seen from miles away, especially at night.

[Z15]

I saw that on FOX news this am. That tower was 700 ft high?

[+seventhings]

Klemmer -

 

Send an e-mail to Deb Brown at NGS and relate the facts of the incident to her. Include, if you can, a link to an online news story about it. Also, send her one or two photos of the no-longer-standing station.

 

Will

[+Klemmer]

Thanks guys, will do. I'm going to swing by & see if I can get some better pics (or LACK thereof......). I figured there wasn't much doubt it was destroyed.

 

BUT what if it it rebuilt in the "same" location? Is it still a valid intersection station????? That's the real question. I'm GUESSING not, but..... Maybe that's a Deb Brown question..... I'll just get her the info, and she can noodle it out.

 

By the way, the darn thing was causing interference (background radio heard) on a few of our phones in the building, well across the freeway. Not anymore!

 

Also BTW, as a private pilot familiar with the area (and also an ex-USAF pilot), I have NO idea why the plane was THAT low at that location. It is considerably below (and outside of) approach pattern altitude to the (somewhat) nearby Fullerton airport. Should be an interesting NTSB accident report. It was also daylight and clear.

[evenfall]

Even if an antenna is reconstructed at this location, the station is destroyed. It has to qualify as the original object. Your submission of news paper articles and news photos should suffice.

 

Welcome to the changing world. Nothing is forever. The intersected point was likely the top, or the light on the top.

 

Surprisingly, and of note, KFI is an AM radio station. AM radio station antennas are peculiar little buggers as many Ham Operators will attest. FM, TV and other types of towers are tall and just simply act as a platform to bolt the antenna to. No particular requirements to the tower design beyond being tall enough to convey the signal appropriately, and strong enough to bear the load in high wind.

 

AM Radio towers are the antenna itself and a very involved, precise design which works only for the designed frequency. Radio Frequency at 850 Khz is a component of how long or in this case tall, that the antenna has to be. However at these very low frequencies the antenna even at a quarter wave length of the frequency wavelength is often impossibly tall for an antenna. What is done to compensate for this is the use of a custom high output power handling antenna matching network, built to specifically work to a specific length of antenna. What this does is allow you to physically shorten the length or height of the antenna, while electrically leaving the tuning in the transmitter with an antenna which seems to it to be the correct length for the tuning, hence the meaning "Match". In addition, there is likely a lot of enhancements done to the ground around that antenna so as to improve it's performance. It is called a ground plane. I am not sure what kind of total antenna system KFI uses but this is likely a quarter wave ground plane system and may be part of what is called a phased array. it is a common type of antenna for use at these radio frequencies.

 

Going forth I would watch to see if a new antenna of similar height and construction is erected in this same location. The reasons why are many, and it is a lot of work, but part of it is that they are FCC licensed, and exhaustively tested for the location, they have a lot of very expensive equipment made to work only as a designed system at this location, New locations are near impossible for AM Stations to find as Hilltops are not where AM antennas work well, They actually work best in low lying areas as they bounce signals off the ionosphere during the day at that frequency, more so than working line of sight. They also often have the capability of making their signals directional at night with the use of a phased array, a second antenna used at the same time, to avoid interfering with other AM stations on the same frequency at night. This combination of ionospheric reflective conditions and antenna directionality are why we can hear distant AM radio stations at night. AM stations are not usually seen as good neighbors to nearby residences as you may hear their station on every appliance in your house if you have grounding problems etc... Being left where they are already established is where they seem to work best. Most all the bugs are worked out.

 

I do wonder what it must have been like in the transmitter shack when the tubes running 50-100,000 watts to that antenna experienced an impedance mismatch by aircraft. Z-z-z-z-z ZAP! I bet it cooked a lot of french fries!

 

I would not be surprised at all if a new and very similar antenna goes up at that site. It won't be the original, and no, it will not be the one in the NGS Database. Asking NGS to have it destroyed is a good call.

 

Edited to Kilomegahertzesessszz... :-)

 

Rob

Edited December 21, 2004 by evenfall

[+Klemmer]

Thanks, Rob. Good stuff! BTW, for future readers, you meant 850 Khz, not MHz. Actually, the station is 640 KHz. Really on the bottom side.

 

An interesting related issue: On an Air Force aircraft I flew (DC-9A), we had HF radios (250 Watts transmitter power, if I recall correctly). The antenna systems was not a long wire system (which some aircraft have stung over them nose to tail), or even a trailing wire system. Ours was a gizmo in the tail about the size and shape of a beer barrel (30 gallons size or so). When you set a frequency in the cockpit, you had to remember to do a momentary mic key, then wait for about 30 seconds while the antenna gizmo did it's thing, and a "tuned" light illuninated on the radio control head. I was back by it (not too close!) when it was tuned once, and it made the strangest collection of whines, whirs, clicks, clacks, grunts, etc. PFM. Pure F..... Magic, we called it. Radio was great. Sometimes over the US, we had to contact, say, the UK or Japan, then get them to give us a phone patch back to the command post in the US. Funky business.

[evenfall]

Klemmer & TeddyBearMama,

 

Hey thanks for the heads up on the frequency, and I corrected the hertz bit. Maybe a little off topic but please forgive, I had to go look at my shortwave radio as I thought I had a preset for KFI... I had 810 khz... I thought it was KFI, but it was actually KGO. I used to listen to it a few years back in the late night when it would come in here in Seattle... My Bad... You never know what you may hear on any given night on AM, It all comes and goes when you are trying to DX AM stations...

 

Rob

[+KX6D]

Hey Klemmer

 

If you want to get close, I'll take you there on Thursday. You can also go yourself and get up close and personal whenever you want. The top section was completely sheared from the rest of the tower and is laying INSIDE the circle enclosure. The light base is still afixed to the top of the tower section, but the glass is obviously gone.

 

I took a ton of pictures today as well.

 

Dino - K6RIX

[mrh - terre haute]

Rob

 

DXing AM radio. I didn't know anybody still did that. Have you WAF or WAS?

 

Mike

 

ps Sorry all for "Off Topic" reply

[evenfall]

Hi Mike,

 

No, I am not sure anyone gives out those awards to short wave listeners anymore. I just have a Grundig YB400 radio, It came with a long wire but I have never used it. I have it plugged into a set of amplified speakers with subwoofer in my shop, it sounds great, like a big stereo would without taking the space or expense, and I listen to it while I do maintenance on some of my surveying tools or other putzing.

 

There are a number of tools that wear quickly from use in the field and you have to constantly keep after them. This time of year the machete needs a light oiling to guard against wet weather as well as their regular sharpening and cleaning. Tape measures need to be unwound and cleaned to help keep them serviceable from use in wet weather, The dirt and grit can really shorten the life of a tape measure, and surveying tapes are a bit spendy. I own my own and I find this is a daily deal this time of year. Hammer faces can get burrs on them, and you want to file them off so you don't inadvertently cut yourself. In some of the work I do, I occasionally use hand levels to determine an elevation quickly and it is a good idea to keep these calibrated and clean. This time of year they are subject to moisture so that is an issue, I also use nimh batteries in a lot of my tools and instruments and various equipment so I do all the recharging and rotating of the batteries... Just like anything else I suppose, you have to take care of the tools that take care of you.

 

So sometimes while I am at it I have used the seek function to see what the AM band has to offer. Most of the time I have not noticed AM propagation to come in well from too far east. The lions share of what seems to come in well at night here comes in from south and southwest. AM is unpredictable at night and you never know what you might find.

 

Rob

Edited December 21, 2004 by evenfall

[+EScout]

KFI Transmitter

Go to this site for photos and explanations of the transmitter, antenna, matching network and more. 50,000 watts and low frequency means everything is very big.

[Wintertime]

We've been discussing this on the ba.broadcast Usenet group. (I don't think there's an equivalent discussion group for Southern California, so we occasionally discuss L.A. stuff on the Bay Area group--especially when it's something this major.)

 

Anyway, here are two other sites that have photos of the destroyed tower:

 

OldRadio.com

 

Sakrison.com

 

There's also a "before" page on OldRadio.com that includes an aerial photo of the area. It's amazing that the tower didn't hit any of those extremely close (light industrial?) buildings on its way down.

 

Patty

Ex-engineer: KKHI, KQED-FM, KSAN, KNEW, KNBR, KYUU

[evenfall]

Hi Patty,

 

I think I will pose this question to you and your experience in Radio Station Engineering,

 

In the event of a ahem, Major impedance mismatch, like say.... A small plane crashing into the station tower, I imagine in a split second the usual impedance goes from it's usual 50 to a blitz between zero infinite amount of ohms in the form of a resistive load seen by the amp as first the amperage and then the voltage climbs with it until the grids in the tubes melt away, unless there is a fusible link or a breaker protecting the tubes... Or the power supply didn't crowbar first... Grid damage seems like voltage would spike on the cathode... And who knows if the protections can react to a tail chase condition on the grid in the tube If not, Eimac is going to make a lot of money... I imagine there could be arc over in a lot of places... That would be one wicked welder. A 4CX25000 doorstop... Afterwards...

 

Of course Tower damage is a given, and KFI is an old station with back up facilities, so to get the main transmitter back after the tower is replaced, how much other damage would you suppose will need to be mitigated? Are the matching network and hardline toast as well?

 

I suspect this is a very, very spendy station engineer's nightmare!

 

I think it took out more than a geodetic landmark. Going back together do you think they will stick with similar specs or attempt new designs, different antenna types, requiring a complete start over, or is standard practice to put it back to as close to as was condition in an updated way, so as to see a new tower of similar height and dimensions that could be mistaken as the original tower?

 

Can you shed any light or save any possible wisdom Patty?

 

Rob

Edited December 25, 2004 by evenfall