Originally Posted by Mac The Knife
Well that was a brutal outage. I missed Elementary because of that one (thankfully I couldn't care less about college basketball so it could have been a lot worse).
What I don't understand about this outage is that KAZT had to turn off their transmitter so that KPHO could go up the tower. But I thought that KAZT 7.1 (which is actually a Prescott station) only had a low power transmitter at their east valley office just for the purpose of providing a signal to Cox cable. So why would that affect KPHO climbing one of the towers on south mountain? And KAZT is already low-power so even if they are on the same tower, why did they have to shut all the way off?
I also noticed that TBN 21.1 powered down for a couple of hours on Thursday night presumably when KPHO went up the tower to diagnose the problem, but they didn't power down during the day on Friday like KAZT when KPHO was actually up on the tower fixing the feedline. WTF?
I'm also a bit stunned that it was a "feedline" failure. That antenna and feedline are only a few years old and the feedline already failed????
The good news is that CBS typically reruns all eps of their successful dramas, so you will likely get another shot at that ep of Elementary.
The rules about who and how far adjacent broadcasters have to power down are pretty strict, and they are there to prevent harming technicians with the radiation levels that they would otherwise suffer (they also wear coveralls that minimize radiation). Normally the rule is that everyone goes to 25% of their normal power and this allows them to still reach 90% of their OTA audience or better. And of course those rules are designed to err on the side of caution.
But a lot also depends on the frequency and just how close the other tower might be, so sometimes some are asked to power down further, especially if they are on the same tower. Bottom line, there are well thought out reasons behind the strategy.
I'm not sure how we know the age of the feedline; KPHO has been OTA with that signal since 1999, and the feedline could predate that. But that is also not even relevant. Feedlines can last for decades. Or a single bullet hole can depressurize the nitrogen and cause a brand new one to burn up.
The key is VSWR and impedance matching. When a feedline fails that all goes to hell meaning more power (up to 5 megawatts effective) can be drawn across the feedline instead of radiating out from the antenna as RF, which is why they burn up as a common method of failure. Monitoring VSWR, which is done regularly, can predict when problems begin, but sometimes there is just a catastrophic failure that can't be predicted.
An otherwise very bright VP-slash-Director of Engineering I once worked under made a famous-last-words statement one day, which was "who needs nitrogen in Arizona?" (feedlines are typically pressurized with nitrogen to prevent water damage and corrosion). Long story short, he dispensed with it and the end result was that we were off the air for 4 days and he nearly lost his job. Not sure if it was ever revealed to the higher-ups exactly WHY there was a failure.
But that is just a simple (well, maybe collosal) brain fart; what I find surprising is that a top station in this market would not have a backup transmitter and feedline/antenna/tower ready to keep the signal available. Stations I work for have had that in place for a decade or more (thanks mostly to smart decisions made by that very same DoE). The money machine stops cranking when you can't reach your viewing audience.
As to the other poster's Q about why there was no video, let me respond with this question, which is "if you had something mission-critical to your operation go wrong on your watch would you be motivated to post video clips on Facebook trumpeting your screwup?" Also, the only pics you could get of someone 1000 ft up on a tower would be from nearly directly below with a long telephoto lens, so would not be very good pics in the first place.Edited by TomCat - 4/13/13 at 3:33pm