On Sunday 29 November 2020 05:32:04 Richard Hector wrote: > On 28/11/20 9:58 am, Gene Heskett wrote: > > Nominal power drain was about 250kwh an hour > > That's about 250kW then? :-)
Yes. The original install had a 250kw sola transformer but it was destroyed by a lightning strike, so it got bypassed, which actually helped the technical operation by removing the noise choking effect of that ton of iron, allowing the local power powerline to absorb to a large extent, the 6 times per hz noise pulse cause by the slow recovery of the high voltage rectifiers, which had the effect of short circuiting the phase with the rising voltage to the decaying voltage of the phase going down. That was about 15 microseconds, 6 times an incoming HZ, and was not only visible as a noise bar slowly running thru the broadcast picture, but was also hell on other stuff plugged into normal wall plugs due the the sudden switch as the diodes finally recovered, which put a nominally 1 kilovolt noise spike sitting on the 127 volts from the wall. Small stuff that ran on 10 watts would suffer random instances of a failed 2 amp fuse due to the cumulative effect of that heat pulse causing a crystalization and eventual fatigue failure of the fuse link metal. The fuse wasn't blown. just broken. The rectifiers could have been replaced with faster ones, but when there are 6 of the sticks about 6 feet long, a 3 phase bridge developing 20 kilovolts for klystron beam power with 72 big diodes per stick, the replacements would have cost something north of $10k so it never got done. Transmitters using klystron amplifiers do not change their power draw with the brightness of the picture and the nearly 6 amps of beam current is not modulated by the video, only the beam velocity is modulated. And at 20 kv, the electrons are moving at definitely relatavistic speeds and that leads to video distortions we didn't then know how to predistort in the opposite to cancel. Now we do have such. The effect is that of changing the length of the tube according to the power level of the output, and was/is caused by the increased mass of the electron as it speeds up, and the decreased mass as it slows down. You could slow them, but you couldn't speed them up to match because they got heavier when sped up, so at high power levels the tube effectively got longer causing timing distortions in the amplified signal. That to me, was prima faci evidence that Einstein was right. And our experiments since have proved him right to a considerable number of zeros to the right of the decimal point. Your trivia factoid overload for the day. Due to the operating expense of such a transmitter, not the least of which was the $125,000 cost of a new tube at 5 year or so intervals, and each NTSC transmitter used 2 of them, newer technology has replaced them and I doubt there are any left on the air here in the US today. Technical considerations has little to do with it, the bean counters will spend the sheckels to reduce the monthly power bill, they have that choice or have the last man out of the building turn off the lights and lock the door. It really is that simple. > Richard Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene>
