Saturday, August 30, 2008

Special to the RMVHFS*, by WB2CBU

SHANAHAN RIDGE, BOULDER. The August 20th "Video Technology" lead article details the status of the DTV transmitters using the new 730’ AGL tower on Lookout Mountain near Golden, CO.

KCNC, VHF Channel 4, DTV UHF Channel 35 is currently running only 24 Kw but will up their power to 974 Kw ERP on 2/17/09. KMGH, VHF Channel 7, DTV UHF Channel 17 is running only 15 Kw now but will go to at least 90 Kw (that's the size of their UPS) on 2/17/09 when they "go back" to VHF Channel 7 for DTV. I think that may be the only transmitting VHF channel left here at that time. KUSA, VHF Channel 9, DTV UHF Channel 16: running half power at 500 Kw now. They'll go to the megawatt ERP on 2/17/09.

The current consequences of the low power transmissions at my location is that although the analog signals from Lookout Mountain were received quite well with a small attic "all band" TV yagi from Radio Shack, a ceiling height fish mobile hidden double bowtie antenna does not recieve KMGH's (old Channel 7) signal at all when aimed to optimize Channel 6, and the more impressive higher gain discrete bedroom antenna needs careful orientation to receive the Denver stations sans Channel 12.

For all it's worth, at my QTH at 5700’ MSL on Shanahan Ridge in SW Boulder I can receive all three with my yagi but have to really work to get Channel 7's DTV signal on the double bow tie antenna. My gosh, CB'ers when I was growing up where probably running 15 Kw. I guess a 16 dB improvement at midnight next 2/17 will fix most people's problems with Channel 4, although their signal is ok here. The 3 dB increase for Channel 9 is not needed at my QTH although the planned 7.8 plus dB improvement for Channel 7 is required for the TV set with only the 6 dB indoor antenna. Now I need to find my VHF rabbit ears just for Channel 7 when they move their DTV signal back there. What a pain.

Although the article was about the Lookout Mountain site, it didn't mention the power for KTVD, UHF Channel 20. DTV VHF Channel 19. Since they’re located a little further south from Lookout, the story didn't talk at all about Channel 6, DTV Channel 18. It’s ok with a little aiming of my UHF antennas. I can't receive the digital signal at all for VHF Channel 12, KBDI, DTV UHF Channel 38 at all. Their website said, "No Boulder coverage until we get a translator sometime in 2009." Phooey on them.

Although I have both digital and analog cable, I watched the Olympics--go Misty May--on DTV off the air. The picture was noticeably higher res than even on digital cable, and the 16:9 format was much better. It seemed they framed their shots for wide screen as often only half a talking head was visible on cable's 4:3 formats where also the front runner or swimmer was off the screen on the 4:3 cropped pictures. It's fun to see that the broadcast stations are all currently transmitting 16:9 wide format but having their newscasters all huddle together in the middle of the desks. They are hedging their bets, I guess. They even superimpose their logos 2/3s of the way over rather than in the upper or lower corner of the screen. It's not clear what the broadcasters will do after midnight 2/17 with their formats since letterbox causes all sets to show a little picture in the picture for conventional material. Good old FCC. Bet they didn't think of all these issues. Why would they? They're the government, and they're here to help us.

There was another article in the most recent Video Technology magazine about how Wilmington, NC is going to all DTV 6 months this September "as a test" to see how well people are prepared. Also all the full powered Orlando stations are broadcasting occasional one minute black pictures on analog with text saying that the viewer is not prepared for digital but with "congratulations" messages on the digital signals as an attempt to encourage the locals to switch over. Unfortunately, the cable companies in Orlando haven't done so yet and are getting lots of phone calls each time the black screen appears and says the opposite of the cable companies' promotions that "you're good to go". You gotta love all this.

I looked at the two local Golden sites in preparation for my graduate video technology class last June. The new 800’ plus tower is pretty impressive even though it starts 100 feet below the top of Lookout. The new transmitter building is also below the mountain top to lower its profile. At least that’s what the Lake Cedar Group says. As for Channel 6, I guess it's quite possible that they are running low power as well. None of the stations mention on their websites or on the air that they are running low power for their digital allocations until midnight 9/17/09, and it’s not a small reduction either in the cases of Channel’s 4 and 7. Two theories as to why they are running QRP are that there are some intermod issues or at least interference/adjacent channel problems with all the analog stations still up and/or they are loath to spend double with Xcel Energy. For all it's worth I can receive Channel 12's analog signal just fine, actually better than the translator on Channel 11. I guess this supports the theory that they are running very low power from Squaw for the DTV UHF signal. It's a shame to not be able to get them because 11-2 is the Documentary Network and would be fun to have available. I did visit Shaw Mountain's transmitter room many years ago when that ham, I think named Bill, lived there (with his lovely wife "Margret" as everyone who checking into the 34/94 net would greet her. Until I met her, I imagined she was like Norman Bates' mom.)

The article also talked about the emergency generators for the LCG stations. A couple of them are using flywheel UPS systems. That has to be an awful big (and heavy) flywheel to hold up a million watt station for 30 seconds until the generators kick in. It would be fun to see the equipment, but from a distance. When I was a kid I would look into the windows of the old generator buildings where the New York Subway had rotary converters to make DC from Con Edison's AC when the the city dropped their own DC generation. These buildings looked and sounded like generation stations but made nothing out their smoke stacks. I was very disappointed when they switched to very big, really very big, non-moving rectifiers.

The power combiner plumbing for the combined antenna for digital Channels 4, 7, 9, and 20 is below. Lookout Mountain pictures are courtesy of K0DK via K0RZ.

*I forgot the name of the Rocky Mountain VHF Society's club newsletter. (Kind of embarassing for the President, I suppose.) I’m sure it started with a Q, but it couldn’t have been QRP or QRM. Maybe QRN or QRZ. Both would have made a lot of sense but not as much as some other local club newsletters. This might be very funny to radio amateurs but might be lost on those not familiar with 100 year old telegraphers' abbreviations: QRP means "low power", QRM is "interferrence", QRN is "noise", and QRZ is the plantive "Is anyone calling me?".