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Old 01-06-2011, 11:09 PM
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What happened to the old analog TV transmitters?

I know many of these perfectly good transmitters were junked after the DTV transition; but, I wonder if any of them were modified for digital and are still being used?

From what I can tell, many of these transmitters were decades old when DTV took over. Our local ABC affiliate was using a transmitter that went on in '74 and I think I remember seeing a YT video of a '53 RCA that was still in service up until the DTV transition.

It's really sad when you think about all these old machines that were junked and likely ended up in China.

And, from what I've seen, the new transmitters are boring, since they consist of a small cabinet with rows of slide out modules. I think I would have liked the old days better; when, they were huge and full of tubes.
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Old 01-08-2011, 09:04 PM
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It depends on the particular situation. Some reasonably good analog transmitters could be converted to digital by substituting a digital exciter. The catch, however, is that stations usually needed to be on the air with both digital and analog during the transition (a few were allowed to do a direct cut), so new equipment had to be bought anyway. In some cases, equipment got cycled around as channel allocations were adjusted. Some stations went on the air in digital using a low power transmitter, then switched their more powerful analog transmitter to digital at the cutover, keeping the smaller digital transmitter as a backup. Or, the analog transmitter was switched to digital and diplexed with the other digital to get 3 dB more power.
In some cases, the analog transmitter was due for replacement in a few years, and the station just hung in there until they could turn it off and NOT replace it.

Edit: in the big cites where the stations lease space on tall buildings, there was a lengthy negotiation period with the stations playing building owners against each other before settling on the final location for the digital transmitters. In Chicago, it was of course Sears Tower vs. Hancock Building - but then there were also several stages of modifying the antenna farm on Sears.

Last edited by old_tv_nut; 01-08-2011 at 09:09 PM.
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Old 01-08-2011, 11:05 PM
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Even after the 6/12/09 extension, our local ABC affiliate had originally planned to turn off their analog transmitter on the original 2/17/09 cut-off date. However, I think the FCC wanted them to stay on, since they are the primary news station in the area.

At about 3 AM on the morning of 6/12, the old analog transmitter went off the air. I think they got it back on around 6 AM, only three hours before the 9 AM analog signal shutdown. Just before the shutdown, the station GM mentioned that, after the deadline extension, they hoped to be able to keep the analog transmitter on the air until 6/12 and that it decided to drop off the air just a few hours prior to it's scheduled shutdown. Then, they showed the old test pattern from '53; followed by a shot of the engineer pushing the button to kill the transmitter. Since that transmitter was from '74, I'm sure it probably was on it's last leg and I doubt they went to much expense maintaining it, since they knew the days of analog were numbered.

BTW, this station was the only one who did an "analog send-off". The other stations simply killed the transmitter during the middle of programming.
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Old 01-09-2011, 09:08 AM
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Quote:
Originally Posted by radiotvnut View Post
BTW, this station was the only one who did an "analog send-off". The other stations simply killed the transmitter during the middle of programming.
We had one local Ch8 that did a pretty good transition program. Still up on Youtube.

http://www.youtube.com/watch?v=obZcfZcbSCU
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Old 01-25-2011, 09:20 PM
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Unhappy ancient analog transmitter junked

[B]I can tell you what happened to one analog tv transmitter here in
Spokane. The station owner gave it to me if I would remove it from
its mountain top building. It was a UHF GE transmitter of the mid 1960s.
Even though I am a ham radio gear builder, there was nothing of use
that came out of this transmitter. There was some 6000lbs of stuff
not including the power transformer. It used a quad of Amperex
klystrons which were made of berylium, which in itself is a first class
hazard. Other not-so-nice stuff was gallons of glycol which had become
very corrosive, and lots of rat stuff. This thing had to be a model
of inefficiency. The station engineer allowed as to how the plate
power in was about 1/4MW and the PEP out was in the order of 40KW.
It took a 50HP blower to cool the glycol heat exchanger. The analog
transmitter's dig replacement was smaller that a refrigerator, and
had way less power output.
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Old 01-26-2011, 10:03 PM
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Quote:
Originally Posted by cork View Post
[B]I can tell you what happened to one analog tv transmitter here in
Spokane. The station owner gave it to me if I would remove it from
its mountain top building. .
A few thousand dollars worth of junk steel, copper, motors.
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Old 01-27-2011, 10:10 PM
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What kind of life did they get out of the tubes?
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Old 02-08-2011, 10:47 PM
markdi markdi is offline
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did you take any pictures ?
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Old 02-13-2011, 06:31 PM
mbear2k mbear2k is offline
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I should have read a little furthur down before posting this:

http://videokarma.org/showthread.php?t=250174
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Old 04-04-2011, 01:01 PM
earlyjukeman earlyjukeman is offline
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NBC transmitter

In 1983 I went to broadcast tech school in Manhattan and we took a trip up to the transmitter room in the Empire State Building. The original 1940's NBC transmitter was still there but not being used anymore. It was untouched except that all the art deco RCA metal logos were missing off the front. Still had all the tubes. My teacher who worked up there told me that it would cost to much for them to remove it and it was free to anybody who could. I was interested in acquiring some of the tubes but never did. CBS still had their transmitter running as a back up to the World Trade Center so they were the only network to stay up on 9/11.

The transmitter room is above the observation deck and techs go outside and climb up to work on the antenna. I looked out of there and you couldn't pay me enough to step out.
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Old 04-13-2011, 08:15 PM
julianburke julianburke is offline
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Here in Knoxville, Channel 10 gave me their RCA TT50's (2 transmitters and had to uninstall them) and of the 6000 lbs (each cabinet weighed about 1000 lbs) mostly went for junk. I wanted to save one but had no where to put it but I stripped out all porcelain tube sockets, bus lines as well as all tubes and all RCA logos and data plates and the meters that were on the top front. I hated that but should have saved at least one cabinet. They were beautifully made with no rivets, all nuts and bolts for serviceability.

What was really funny and to see the monkey dance, was a huge pile of solid copper transmission line, cavities and combiner scrap about 5 feet high and about 12 feet in diameter. The old transmitters had to be removed as the space was being remodeled and when a new worker/contractor/block mason would come in and saw this huge pile of copper, their eyes would get this BIG and always ask what we were going to do with it. I would tell them that we could use help to put it in the dumpster and I couldn't do it all by myself!! Tee Hee Hee!!! Their expressions at that point was worth the price of a ticket!! The copper brought about $8000 scrap and was divided among the engineers for all the extra work.
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Last edited by julianburke; 04-13-2011 at 08:28 PM.
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