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Transmitters on mount wilson.
- Thread starter 30james
- Start date
Hey guys I was wondering how durable are the transmitters that sit on mount wilson. Have they ever falling over in a santa ana event. Just curious.
Transmitters are usually inside buildings, protected from the elements. I'm assuming you're meaning the towers the antennas reside on that are fed by the transmitters.
Transmitters are usually inside buildings, protected from the elements. I'm assuming you're meaning the towers the antennas reside on that are fed by the transmitters.
The ridge up on Wilson is quite wide and the buildings ar very strong. Towers are built to withstand even hurricane type winds. Most are very short, around 200 feet…except for Channel 2 and CBS-Fm on a 1000 foot tower on the flat area to the northern end of the ridge.
Is KCBS-2 still on the same array and height as they were in the analog days? I mean if it ain't broke don't fix it but since KCBS-2 broadcasts in the UHF band now there is really no need for such a massive tower height, right?
Any radio or TV transmission above around 30 t0 40 MHz depends as much on height as it does power. That means FM and all the TV channels. It does not matter if the transmission is digital or analog, at those frequencies there is essentially no ground wave coverage so reception depends on line of sight to the end user... the higher the tower, the better the coverage.
This is a lay explanation. I'm sure that the engineers here who are far better qualified that I am can expand on this.
In the 80s when we lived in Alta Loma near the foothills, Getting channel 2 was always a challenge despite enhanced rooftop antenna due to line of site issues. Have to go to friend's house further down the hill to watch the Rams games. Too cheap to get cable!
Part of that is that antennas don't send signal straight downwards. That is to protect people in the transmitter building and surrounding thousand feet or so from intense and potentially dangerous RF. The signal might leave the antenna with aimed in an arc of perhaps 30° to 45° to 50° above straight downwards to focus the power on the population out a mile or two to 30, 40, 50 miles out.
Putting all the signal in a narrow beam is how a 10 kw transmitter can radiate (ERP) 100 kw... all the power is in a thin beam. Sort of like the difference between a flashlight bulb stuck on the end of a wire versus one with a reflector behind it to narrow the light beam and make it seem much brighter.
KCBS-TV is back on their old 975 ft tower as is KDOC-TV joining them as are various LPTV stations.
That is definitely food for thought. Thanks!
i believe the CBS tower is the only guywire tower up there the others being free standing.
That is correct about the old KCBS tower at 123 CBS Lane as being the only guyed tower at Mt. Wilson. It is now owned by American Tower. It is 975 Ft tall plus the KDOC and KCBS antennae.
Lately the big issue on Mt Wilson seems to be fire.
www.cbsnews.com
Fire Near Mount Wilson TV Towers, Observatory Burns 30 Acres
A huge plume of smoke was visible across the Los Angeles basin and surrounding valleys after the flames broke out before dawn near the 5,710 foot peak.
www.cbsnews.com
The most dangerous for radio and TV was the 2009 Station Fire, which made a number of FMs build auxiliary sites down in the LA basin.Lately the big issue on Mt Wilson seems to be fire.
Fire Near Mount Wilson TV Towers, Observatory Burns 30 Acres
A huge plume of smoke was visible across the Los Angeles basin and surrounding valleys after the flames broke out before dawn near the 5,710 foot peak.
I have heard that the distance between the guywires at the ground is nearly one quarter of a mile!
Isosceles triangle formations for the top guy are fairly common. The tower itself is nearly 1/5 of a mile high, so having the top guys out 1000 feet would not bee strange. If you go to far out, the pull and weight of the guys become overly significant.
I once worked at KCBS-TV, and I heard the reason why they built such a high tower (in the 1980's, I believe) was because of their site on the north end of Mt. Wilson. CBS-2's main competitors (KNBC and KABC) were further south on the mountain, and therefore had better line-of-sight to the eastern foothill communities (Bradbury, Sierra Madre, etc).
They had better coverage in the north SFV as well. Ch 4 at one time I think had the tallest tower up there, over 500 ft.
I can vouch for what Signal Geek heard.
Several years back, I had a conversation with the owner of KFLA-8, trying to understand why I couldn't get a usable signal for his station despite him renting space on the KCBS tower. From my location in Covina at the time (the bottom of the eastern SGV's bowl and home to lots of dense population), I could see that tower very clearly by day, and its FAA lights at night.
It wasn't until a few go-arounds that I realized only the top x% of the tower was actually visible to me (I no longer remember exactly how much). Another peak on Mt. Wilson was covering the bottom part of the tower, and KFLA-8's antenna was just beneath that peak.
So you can add a the large, dense population areas in and around the center of the eastern SGV to the list of locations KCBS' tower was built extra high to reach.
(Postscript: KFLA later moved its antenna further up the KCBS tower to extend its own reach as well.)
Several years back, I had a conversation with the owner of KFLA-8, trying to understand why I couldn't get a usable signal for his station despite him renting space on the KCBS tower. From my location in Covina at the time (the bottom of the eastern SGV's bowl and home to lots of dense population), I could see that tower very clearly by day, and its FAA lights at night.
It wasn't until a few go-arounds that I realized only the top x% of the tower was actually visible to me (I no longer remember exactly how much). Another peak on Mt. Wilson was covering the bottom part of the tower, and KFLA-8's antenna was just beneath that peak.
So you can add a the large, dense population areas in and around the center of the eastern SGV to the list of locations KCBS' tower was built extra high to reach.
(Postscript: KFLA later moved its antenna further up the KCBS tower to extend its own reach as well.)
That is correct about the 975 ft KCBS tower at what is now called Deer Park since it was sold to American Tower. It is at the same height at the top of the KNBC tower. The problem with KCBS site is that there is blockage towards the East. I too worked at that site 1981-82.
And then there's Mt. Harvard, slightly lower but further south on the ridgeline than either Mt. Wilson or Deer Park. On Google Maps you'll see it flagged as the site for KWHY-TV. KUSC and a couple of other FMs are there, along with a whole bunch of two way transmitters. It has much better close in coverage in foothill areas like La Canada-Flintridge than either of the other sites.
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