Eric Jacobsen wrote:> > On Tue, 04 Sep 2007 15:16:32 -0400, "Michael A. Terrell" > <mike.terrell@earthlink.net> wrote: > > >"Gene E. Bloch" wrote: > >> > >> > On 9/04/2007, Michael A. Terrell posted this: > >> > > >> > Its obvious that you've never built a TV station from the ground up. > >> > Even a spare 10% transmitter power capacity could cost a couple hundred > >> > thousand dollars in capital assets. and its unlikely the governing > >> > agency will allow you to use equipment capable of excess power, any more > >> > than you can build whatever tower height you want. It costs millions of > >> > dollars to build a full power commercial TV station. > >> > >> Do you *really* think I've never built a TV station from the ground up? > >> > >> Really? > >> > >> Well, you're correct. > > > > > > I HAVE built a complete TV station, starting with an empty building > >and no tower. > > > > > >> It doesn't keep from speculating, however. > > > > > > Speculate all you want, and let everyone see that you have absolutely > >no grasp of the subject. > > > > > >> For example, it *might* be true that it's a good idea to spend extra > >> money to put in safety factors (although, to be fair, I *do* run my > >> 100W lightbulbs at 100W). It could be cheaper in the long run than > >> fixing the reasult of not doing so. > > > > > > Do you know that a TV station's EIRP is transmitter power output, > >multiplied by antenna gain? > > ...less cable losses and backoff. > > Cable loss is pretty substantial in most broadcast applications. > > Nevertheless, transmitter headroom on broadcast amplifiers is pretty > expensive, as has been mentioned. So even getting a dB or two of > headroom can be not only a big NRE cost, but cost a lot of power > consumption during operation. The "black picture" thing is a real > concern in most NTSC transmitters, but it's pretty much just a typical > engineering concern of limiting the amount of black-picture time to > keep the thing from overheating or exceeding whatever spec is limited > by that particular design. And I've never run across an NTSC > transmitter, even a reasonably cheap one, that didn't have automatic > protection circuits that would keep the PA safe even if conditions > went wonky. i.e., it's tough to really damage one of those dude. > > Not to say that I haven't done it. ;) A low-power NTSC transmitter > for which I used to be responsible went through a long string of PA > tubes, all covered by the manufacturer, before we figured out what was > wrong with it. > > Eric Jacobsen > Minister of Algorithms > Abineau Communications > http://www.ericjacobsen.orgThe lowest power NTSC transmitter I ever used was a 90 Watt gates on Ch 8 at an AFRTS TV station. It was a standby transmitter, but every panel in it fit the exciter cabinet of the matching Gates main transmitter. This was late '60s design, and I was using it in '73 & '74. That station was intended to only cover the base. Some idiot ham radio operator had the transmitter so screwed up, it wouldn't operate. He was trying to tune it, like he did his beat up old Swan SSB mobile. Both transmitters were damaged when i arrived. It took the better part of a week to find the problems, only to discover that replacements for the damaged parts had been ordered 18 months earlier and were still on backorder. So they had 90 watts of Visual power, from the standby transmitter and over 250 Watts of Aural power from the main transmitter. I did some scrounging and found the needed parts and repaired both transmitters. After a full alignment of the 500 W transmitter, the output was 756 watts. I backed it down to an even 600 and ran it that way for the year I was in charge. The biggest transmitter I maintained was a 130 KW Comark (Thales) on Ch 55, with a 5 MW EIRP and a 1749 foot tower. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida
Visual "clipping"?
Started by ●September 4, 2007
Reply by ●September 4, 20072007-09-04
Reply by ●September 4, 20072007-09-04
On Tue, 04 Sep 2007 17:06:52 -0500, Richard Owlett <rowlett@atlascomm.net> wrote:>I challenged *YOU* to defend whacko claim!!!Funny how every thread started by Radium, quickly turns into a slapfest. -m- -- Official website "Jonah's Quid" http://www.jonahsquids.co.uk
Reply by ●September 4, 20072007-09-04
On Sep 4, 12:17 pm, Richard Owlett <rowl...@atlascomm.net> wrote:> Michael A. Terrell wrote: > >[snip] > > > Never worked at a TV transmitter site, have you? If they are > > operating under the specified power, they are in violation of their > > license, ... > > *WHAT?* > Please quote a specific regulation that _prohibits_ operating at *LESS* > than authorized power. My commercial license (2nd class phone) may have > expired 40 years ago, but I never heard of such. We even had a backup > 1Kw transmitter for when our 50Kw transmitter went down. There were > occasions (ice storms) when we switched to backup BEFORE primary went > down as it was more tolerant of bad SWR. [now this was an FM rather than > TV but don not see difference for this case]We were required to be between 80 and 110% of licensed power - commercial low band VHF TV. Any deviation from that required log entries for the day it happened. I'm not certain of the procedure if it was going to be for any length of time but I'm certain there would be exchanges with the local FCC office. As for a low power backup transmitter, it was licensed at that power and certainly required log entries when it is on line. If the main transmitter is going to be off line for a while, I'm sure that would also require contact with the FCC. GG
Reply by ●September 4, 20072007-09-04
Martin Heffels wrote:> > On Tue, 04 Sep 2007 12:56:25 -0400, "Michael A. Terrell" > <mike.terrell@earthlink.net> wrote: > > > In the US a station has to notify the FCC if they are not operating > >at the power they are licensed for. > > True, but �73.1560 of the FCC regulations says: > > <quote> > (c) TV stations. (1) Except as provided in paragraph (d) of this section, > the visual output power of a TV or Class A TV transmitter, as determined by > the procedures specified in Sec. 73.664, must be maintained as near as is > practicable to the authorized transmitter output power and may not be less > than 80% nor more than 110% of the authorized power. > </quote>Not one engineer worth his paycheck would try to run that close to the bone. The 80% figure was the lower limit for aging final tubes. If you were at 80% and the line voltage dropped a couple percent, you are automatically operating out of spec. The 110% upper limit was to allow for power line fluctuations in the other direction. Not many TV transmitters were run from a Sola Adjust-A-Volt stepping regulator. I kept to within +/- 3% of the rated power for civilian operations.> So they could run at 80% theroretically, with the excuse that receivers > have improved, and people who live in the grade-B zones (or grade-Z ;-) ), > will probably have satellite-receivers by now anyway. Saving them a lot of > meny, and not actually violating the FCC-regulations.Theoretically, aliens could have built the station to be self repairing, and powered it with a ZPM. TV is a competitive business, and reducing power to save money is a sign they are going bankrupt. The 5 MW UHF station I engineered at paid out a little over $45,000 US dollars a month to power the transmitter. that was less than half the monthly operating budget for the station. if they wanted to save money, they reduced the cost of heating and cooling the offices and studios, or laid off a couple people, but they NEVER reduced power. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida
Reply by ●September 4, 20072007-09-04
Richard Owlett wrote:> > Michael A. Terrell wrote: > > Richard Owlett wrote: > > > >>Michael A. Terrell wrote: > >> > >>>[snip] > >>> > >>> Never worked at a TV transmitter site, have you? If they are > >>>operating under the specified power, they are in violation of their > >>>license, ... > >> > >>*WHAT?* > >>Please quote a specific regulation that _prohibits_ operating at *LESS* > >>than authorized power. My commercial license (2nd class phone) may have > >>expired 40 years ago, but I never heard of such. We even had a backup > >>1Kw transmitter for when our 50Kw transmitter went down. There were > >>occasions (ice storms) when we switched to backup BEFORE primary went > >>down as it was more tolerant of bad SWR. [now this was an FM rather than > >>TV but don not see difference for this case] > > > > > > > > That is an emergency situation, not normal operation. If any single > > emergency lasted more than three days, the FCC required notification. If > > a station is 'dark' more than a set number of days because of equipment > > failure, they can lose their operating license, and have to fight anyone > > else who wants that frequency allocation when they reapply for a > > operating license. They may also be required to repalce any oldder, adn > > all defective equipment that was grandfathered under the old operating > > license. > > > > > > All the FCC requlations are part of Title 47 CFR, so help yourself at > > the link below. There are months of reading involvled to wade through > > all of it. > > > > http://www.gpoaccess.gov/cfr/index.html > > > > NO WAY!!! > > YOU claimed it was illegal to operate below rated power. > I challenged *YOU* to defend whacko claim!!!I don't chat with screaming idiots. Goodbye. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida
Reply by ●September 4, 20072007-09-04
Martin Heffels wrote:> > On Tue, 04 Sep 2007 17:06:52 -0500, Richard Owlett <rowlett@atlascomm.net> > wrote: > > >I challenged *YOU* to defend whacko claim!!! > > Funny how every thread started by Radium, quickly turns into a slapfest.Hear that sound? I just flushed 'Slappy' down the toilet. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida
Reply by ●September 4, 20072007-09-04
On Mon, 03 Sep 2007 20:03:04 -0700, Radium <glucegen1@gmail.com> wrote:> >Clipping in an audio signal results when an audio device receives a >signal that is too loud. The audio signal distorts into square-waves >because the "tops" of the signal are flattened. The device cannot >handle power levels over a certain level. When this level is exceeded, >clipping occurs. Clipping is usually harsher in digital devices than >in analog devices. Analog clipping tends to be fuzzy and soft compared >to digital clipping.Sounds like crap to me!>What is the visual-equivalent of "clipping"? Is there a difference >between analog and digital in terms of visual-clipping? If so, what is >the difference? > >Auditory-clipping can damage speakers. Can visual-"clipping" damage >monitors?More crap! If the words visual or auditory are both a response to a human sense then how did these two words get mutilated into something that can damages speakers, burn CRT's, etc. Visual-clipping would be Supermans X-ray vision which was considered cutting edge at that time. Auditory-clipping would be what Superman heard the many times he met his own sound barrier crack during each lap around the earth, over and over to move time backwards and save Louis. Keep up the imagination Radium, there is a method to your madness. * * * Christopher Temecula CA.USA http://www.oldtemecula.com
Reply by ●September 4, 20072007-09-04
On 9/4/07 12:17 PM, in article 13drbm77vm4rm62@news.supernews.com, "Richard Owlett" <rowlett@atlascomm.net> wrote:> Michael A. Terrell wrote: >> [snip] >> >> Never worked at a TV transmitter site, have you? If they are >> operating under the specified power, they are in violation of their >> license, ... > > *WHAT?* > Please quote a specific regulation that _prohibits_ operating at *LESS* > than authorized power. My commercial license (2nd class phone) may have > expired 40 years ago, but I never heard of such. We even had a backup > 1Kw transmitter for when our 50Kw transmitter went down. There were > occasions (ice storms) when we switched to backup BEFORE primary went > down as it was more tolerant of bad SWR. [now this was an FM rather than > TV but don not see difference for this case] > >As I recall all broadcast stations had to file a report if they needed to run at reduced power.
Reply by ●September 4, 20072007-09-04
On 9/04/2007, Michael A. Terrell posted this:> "Gene E. Bloch" wrote: >> >>> On 9/04/2007, Michael A. Terrell posted this: >>> >>> Its obvious that you've never built a TV station from the ground up. >>> Even a spare 10% transmitter power capacity could cost a couple hundred >>> thousand dollars in capital assets. and its unlikely the governing >>> agency will allow you to use equipment capable of excess power, any more >>> than you can build whatever tower height you want. It costs millions of >>> dollars to build a full power commercial TV station. >> >> Do you *really* think I've never built a TV station from the ground up? >> >> Really? >> >> Well, you're correct.> I HAVE built a complete TV station, starting with an empty building > and no tower.Immune to humor, are we? <SNIP> -- Gene E. Bloch (Gino) letters617blochg3251 (replace the numbers by "at" and "dotcom")
Reply by ●September 4, 20072007-09-04
On 9/04/2007, Tim Wescott posted this:> Gene E. Bloch wrote: >> On 9/04/2007, Michael A. Terrell posted this: >>> "Gene E. Bloch" wrote: >>>> >>>> On 9/04/2007, Michael A. Terrell posted this: >>>>> Martin Heffels wrote: >>>>>> >>>>>> On Tue, 04 Sep 2007 12:23:52 -0400, "Michael A. Terrell" >>>>>> <mike.terrell@earthlink.net> wrote: >>>>>> >>>>>>> Never worked at a TV transmitter site, have you? If they are >>>>>>> operating under the specified power, they are in violation of their >>>>>>> license, and no one is stupid enough to overbuy on the transmitter >>>>>>> requirements. >>>>>> >>>>>> Help me here..... Since when would this be a violation? A >>>>>> transmitter-license usually states the _maximum_ amount of power, so >>>>>> what >>>>>> is different here? Stories are plenty of radio and television-stations >>>>>> cutting down their power for power-saving reasons (money, money, >>>>>> money). >>>>> >>>>> >>>>> In the US a station has to notify the FCC if they are not operating >>>>> at the power they are licensed for. It has to be logged on a set >>>>> schedule and kept in the station's permanent files for the FCC field >>>>> inspectors. If a station is operating below the level they are licensed >>>>> for, they are not serving the area they agreed to provide service to. >>>>> VERY few stations were ever allowed to differ from their rated power. >>>>> The only two I ever saw were on military bases where the transmitter >>>>> power was listed, with "Or as deemed necessary". These were in remote >>>>> locations and major repairs were consider as 'Depot Level' repairs. >>>>> Reduced or increased power was allowed, to stay on the air, but none of >>>>> these were high power stations. The license was deemed a 'Courtesy >>>>> License' by the FCC, which meant that they had little authority over a >>>>> military transmitter, but the 'Courtesy License' was granted to make >>>>> sure the frequency coordinators didn't assign a civilian station an >>>>> allocation that would interfere. >>>>> >>>>> >>>>> If your power level is too high, you can cause problems for other >>>>> stations, and if it's too low, your advertisers will demand refunds. >>>>> >>>>> I was a broadcast engineer at one military and two civilian TV >>>>> stations over a 17 year period. I lost count of the AM radio stations I >>>>> did work for, or located parts and equipment to keep on the air. >>>> >>>> However, the original remark was not about the *licensed* power, it was >>>> about the *rated* power. I.e., the electrical or electronic limits, not >>>> the legal limits. >>> >>> >>> Its obvious that you've never built a TV station from the ground up. >>> Even a spare 10% transmitter power capacity could cost a couple hundred >>> thousand dollars in capital assets. and its unlikely the governing >>> agency will allow you to use equipment capable of excess power, any more >>> than you can build whatever tower height you want. It costs millions of >>> dollars to build a full power commercial TV station. >> >> Do you *really* think I've never built a TV station form the ground up? >> >> Really? >> >> Well, you're correct. It doesn't keep from speculating, however. >> >> For example, it *might* be true that it's a good idea to spend extra money >> to put in safety factors (although, to be fair, I *do* run my 100W >> lightbulbs at 100W). It could be cheaper in the long run than fixing the >> reasult of not doing so. >> >> The above has certinaly been true in civil construction for millennia. >> > Oh. So that's why small rural bridges never have weight limits posted on > them? > > Not.OK. So?> Any system has to be designed with some sort of limits in mind.I seem to have said that already.> If the > broadcasters want to make decisions about how much of a screen can be black > and for how long, it's their decision to make.Yes. They almost certainly would not follow my advice. In fact I'd recommend *very* strongly that they ignore my advice :-) -- Gene E. Bloch (Gino) letters617blochg3251 (replace the numbers by "at" and "dotcom")
