ChuckCobleigh Well, 100 Mhz MECL (Motorola's high speed product) was kind of a power hog, as I recall. Watts-in meant watts-out in heat. Then again, a 60 kW UHF TV amplifier with 40% efficiency meant that the heat exchanger with the 10-horse blower motor better not fail.
Well, 100 Mhz MECL (Motorola's high speed product) was kind of a power hog, as I recall. Watts-in meant watts-out in heat. Then again, a 60 kW UHF TV amplifier with 40% efficiency meant that the heat exchanger with the 10-horse blower motor better not fail.
In the early days of FM broadcsting, a station in Asheville proclaimed that its transmitter was "high above Clingman's Peak atop Mount Mitchell." This put it on top of the highest mountain east of the Mississippi--6,684 feet. It was easily heard fifty miles south of Charlotte.
Johnny
tree68I haven't really studied FM station broadcast patterns - I've always figured they were omnidirectional.
The 'native' idea is to shape the emission pattern to omni, but in the horizontal plane so the signal doesn't drop off as for spherical propagation but proportional to distance.
In practice the idea is to tinker with the radiators so that the 50-microvolt contour is 'further away' in those demographic areas with more prospective listeners. I confess that one of the reasons we were so strong in the Arbitrons (for a "college" radio station) was that we had a little selective patterning toward the New York and Philadelphia suburban areas. (One amusing thing to note was that I was able to receive PRB in Englewood after one round of 'adjustment' on my fancy Luxman tuner, whereas I couldn't 'before')
Equally amusing is that we no longer broadcast from the top of the second-highest building in Mercer County: we have a link to transmitter and emitters on a 2000' tower near West Windsor, the result of our allowing another station (ISTR around 103.5) to put a translator booster in northern New Jersey. When they asked how much we wanted to allow this, the then station management jokingly said 'a million dollars' -- which they promptly agreed to without demur! This was invested with the guys who run PRINCO, so has done predictably well in the years since... we're not hurtin' for production equipment, or much of anything else, even if you now require far more selectivity to receive us in the northern New Jersey area...
Of course, the best reception at night was always on the car radio. I can remember driving through Nebraska at night and picking up WLS in Chicago, KOMA in Oklahoma City, the hometown broadcasts of both teams in an NBA game, among other things.
Transistor radio? what's a transistor radio? When I took time out ftom the fourth grrade with rheumatic fever, I had a TRF (tuned radio frequency) radio by my bed, and I could listen to far away stations late at night. When in high school, I built a radio with a superheterodyne circuit (with a high voltage power supply), and I would listen to music from the ballroom in the Roosevelt Hotel in New Orleans, using a pillow speaker, late at night--and wake up to a station a few miles north of Charlotte, N.C. in the morning.
BaltACDI listen to a station out of Baltimore 105.7 FM - If I go 15 miles West of my location, I exceed it's broadcast coverage area. If I go 15 miles North of my location its broadcast area overlays at station from Southern Pennsylvania. Make a turn and I lose the Baltimore station and get the PA station - make another turn and vice versa.
I haven't really studied FM station broadcast patterns - I've always figured they were omnidirectional.
Many small-town AM stations went (and probably still do go) directional at night. That's why you often see clusters of three or four antennas for such stations. With proper phasing, the night coverage can get pretty specific.
Some reduced power at night, or did both.
This is, of course, due to the tendency of the AM frequencies to skip. Kids today don't know the thrill of hiding under the covers at night, tuning through the dial on a transistor radio to seek out distant stations.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
BaltACDWLW and its 500Kw transmitter
My Electrical Engineering class in 1956 had a tour of the WLW campus in Mason OH and we saw the 500 KW transmitter with its water cooled (Pyrex piping) transmitter retired in place and the its 50 KW modulator now the on the air transmitter. We allso saw the Voice of America short wave transmitters that had been built in 1944. It was supprising to hear a transformer that was the size of a 40 MW power transformer (over 8 ft tall) "talking". The VOA went off the air in '94. And ham's might be interested in the details of the VOA (voice of america) transmitting facility. https://www.youtube.com/watch?v=3w_ZXRJol_4
tree68 BaltACD Today commercial stations are limited to 50Kw. And I believe that's limited to "clear channel" stations on the AM side - those that pretty much have the frequency to themselves.
BaltACD Today commercial stations are limited to 50Kw.
And I believe that's limited to "clear channel" stations on the AM side - those that pretty much have the frequency to themselves.
I listen to a station out of Baltimore 105.7 FM - If I go 15 miles West of my location, I exceed it's broadcast coverage area. If I go 15 miles North of my location its broadcast area overlays at station from Southern Pennsylvania. Make a turn and I lose the Baltimore station and get the PA station - make another turn and vice versa.
Never too old to have a happy childhood!
BaltACDToday commercial stations are limited to 50Kw.
ChuckCobleigh Erik_Mag As for cooling, Seymour Cray talent was as much for cooling systems as it was for computer architecture. For the CDC-6600, there were more patents for cooling than anything else involved with that system. Well, 100 Mhz MECL (Motorola's high speed product) was kind of a power hog, as I recall. Watts-in meant watts-out in heat. Then again, a 60 kW UHF TV amplifier with 40% efficiency meant that the heat exchanger with the 10-horse blower motor better not fail.
Erik_Mag As for cooling, Seymour Cray talent was as much for cooling systems as it was for computer architecture. For the CDC-6600, there were more patents for cooling than anything else involved with that system.
WLW and its 500Kw transmitter
https://en.wikipedia.org/wiki/WLW
Today commercial stations are limited to 50Kw.
ChuckCobleighThen again, a 60 kW UHF TV amplifier with 40% efficiency meant that the heat exchanger with the 10-horse blower motor better not fail.
When I started at WPRB, we had one of the very first Collins stereo FM radio transmitters -- relatively high output tube power of just under 10kW (ERP 17kW). The cooling for the final stages was, as you note, fairly critical -- and one night the plate safety dropped out because the blower to it failed.
Surprisingly when we got it out, we discovered there had been a manufacturing error -- the blower had a 120V motor but was running off 220V supply. This understandably led to a pretty quick complaint call to Collins Radio -- who informed us this was an intentional design decision, as the blower could be fit entirely in the duct plenum ... and the considerable airflow would keep any, ahem, overheating of the motor within its design rise. Of course, if the intake filters started to clog, or there was an decrease in flow anywhere including at exhaust, the thing would rather promptly fail -- but as with crankcase explosions in Cat 35xxs, it's the user's fault, a 1970s version of 'you were holding it wrong'.
Now our Chief Engineer was not -- heck, no one particularly sane would be -- going to spend several hundred dollars and a courier delivery charge to C.S.Collins for a replacement kludge. It was then that someone remembered seeing part of an oil-burning furnace put out to the curb for trash collection -- we 'adaptively reused' it connecting the blower output right up to the duct with the inline blower just omitted. Looked and sounded just like a furnace ... and we had no subsequent issues with any aspect of cooling.
Erik_MagAs for cooling, Seymour Cray talent was as much for cooling systems as it was for computer architecture. For the CDC-6600, there were more patents for cooling than anything else involved with that system.
CSSHEGEWISCHIn railroading in 1970, consider that HEP for passenger trains was primarily confined to suburban trains, everything else used steam heat and underfloor batteries for light.
It's not that primitive. Keep in mind that HEP was commonly used on early streamliners (remember that Zephyr with all the little Cummins engines providing the hotel power?) and that Santa Fe used steam-ejector air conditioning long after the era of steam passenger power.
The chief reason was, I think, similar to the current issue over implementing ECP in the presence of pressure-maintaining: a common set of standards for all cars in interconnect, combined with common assurance of a proper power source on every train. The alternative -- which of course is what was pursued in reality -- was autonomous power on every car. Which might be done with Spicer drives off the trucks, or Enginators/Ice Engines, in conjunction with the very large battery storage. That this was the 'wave of the future' for the massively more power-consuming postwar streamliners is easily seen as early as Kiefer's motive-power survey in 1947, where he specifically mentions how the acceleration profile is affected by the various points where the axle drives kick in, and then load down progressively. This substitutes instantaneous drawbar TE for head-end power to a trainlined bus... and of course leaves all aspects of maintenance and service to the individual roads that purchased and maintained individual cars. All that needed to be common across intercar connections were the typical required things like brake control or signal lines.
There are significant safety issues associated with 'interchange' HEP, both those associated with having to manipulate the cabling and with potential shorts or other issues concerned with cable degradation, damage, or inadvertent disconnection. Those are not issues on individually-powered cars. Neither are incompatible electrical standards, or workarounds should the HEP bus on one car midtrain become damaged or disconnected.
Meanwhile -- review the operation of steam-ejector air conditioning vs. electrically-driven alternatives, especially in chronic hot weather and typical railroad operating and maintenance conditions. I believe Erik did a good analysis, with diagrams, in an older post here (but with community search disabled it might be necessary to find it with a search engine like Google ... good luck!)
SD60MAC9500 54light15 It's interesting how auto-carriers are fully enclosed in North America but in Europe, they're still open. But imagine the electrical load of all those huge 1970 vintage computers and you know they're only going to get bigger in the future, right? Auto component theft and vandalism are still issues here Stateside more so than in Europe.
54light15 It's interesting how auto-carriers are fully enclosed in North America but in Europe, they're still open. But imagine the electrical load of all those huge 1970 vintage computers and you know they're only going to get bigger in the future, right?
It's interesting how auto-carriers are fully enclosed in North America but in Europe, they're still open. But imagine the electrical load of all those huge 1970 vintage computers and you know they're only going to get bigger in the future, right?
Auto component theft and vandalism are still issues here Stateside more so than in Europe.
No surprise. In Europe you do the crime, you do serious time. They don't fool around over there.
I got it from the source, some European friends from various countries.
Here is a little trip down memory lane for Erik et al. about the ways this stuff was supposed to go in the '80s:
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.84.7180&rep=rep1&type=pdf
This paper itself is nearly 20 years old now!
Ah, the good old days when we called it MIMD and Beowulf was something lit majors discussed...
Cooling was indeed a major issue at that time. In a previous job, I worked as a tape librarian in the computer room of a major Chicago bank. One day, one of the ventilation ducts was blocked and operations deteriorated since the computers couldn't function properly in higher temperatures.
In railroading in 1970, consider that HEP for passenger trains was primarily confined to suburban trains, everything else used steam heat and underfloor batteries for light.
Considering that my newest laptop has more memory and procressing power than a Cray 2...
First time I learned about UPS's was at an EECS department power systems seminar in 1975. These were the always on type with a static switch to take over if the UPS failed, battery was sized to carry the load until the back-up generator kicked in. Some where designed with a 400Hz inverter for certain mainframes.
As for cooling, Seymour Cray talent was as much for cooling systems as it was for computer architecture. For the CDC-6600, there were more patents for cooling than anything else involved with that system.
Water-cooling? Freon, then cryogenics for Josephson junctions.
There was a phony ad in the back pages of Byte Magazine in the late Seventies -- "Cray-1 on a chip! Plug it into a penlite battery and watch it go!!" How we laughed and laughed.
Much less than fifty years later, this:
https://www.extremetech.com/extreme/191877-how-to-build-your-own-110-scale-cray-1-supercomputer
Note near the end that he'll send you the Verilog files for free...
Flintlock76 Tree, Lady Firestorm asked me to tell to that when she worked for Bradford Inc. in Teaneck NJ in 1978 they had an IBM 3030, water cooled, plus an air conditioning unit in the computer room. It was like an icebox in there! I can't imagine that much juice running through those machines!
Tree, Lady Firestorm asked me to tell to that when she worked for Bradford Inc. in Teaneck NJ in 1978 they had an IBM 3030, water cooled, plus an air conditioning unit in the computer room. It was like an icebox in there!
I can't imagine that much juice running through those machines!
We had three phase power into the building. A UPS ran all of the power for the computing and communications equipment - it rectified the 3 phase AC, ran the DC across a large battery bank, then turned it back into the 3 phase AC.
I forget the rating on the old UPS, or the new one I had installed to replace it, but the new one had several hundred deep cycle batteries to maintain the 400 volts DC. It was rated to run the entire computer room for two hours.
The UPS took up an entire room. I believe the generator in the next room was a 60K... That one has since been replace with a much larger version...
The main switch for the telephone system was in the same building, but they had their own batteries.
Flintlock76Tree, Lady Firestorm asked me to tell to that when she worked for Bradford Inc. in Teaneck NJ in 1978 they had an IBM 3030, water cooled, plus an air conditioning unit in the computer room. It was like an icebox in there! I can't imagine that much juice running through those machines!
Saw the electric cables that were used to power the Chessie System Main Frame computers that were on the top floor of the B&O Building in Baltimore - Cables were the size of ones wrist - 1 1/2 to 2 inches in diameter. Early computers were power hogs that generated a lot of heat and were heavy besides. The micro electronics we know today had yet to be invented. Remember some of the earliest used vacuum tubes.
When my departments offices were on the 11th Floor of the 2 North Charles Street building (Balimores first 'urban renewal' office building designed by Meis vander Roe, I was told) in the early 80's - the desk top CRT screens that most of those that occupied the floor used as a part of their duties severly overloaded the air conditioning that was from when the building was built in the early 1960's - the designers never considered the occupants as having multiple heat generating units of office equipment.
54light15But imagine the electrical load of all those huge 1970 vintage computers and you know they're only going to get bigger in the future, right?
The heat load was significant - our computer room had three very large air handlers running at all times. During periods when the machines weren't "producing," it could get downright chilly there.
Right now, in my ham shack, I have a 6"x6"x2" microcomputer that has more processing power, more RAM, and more hard drive space than the IBM 4361 we were using. The processor itself was the size of three washing machines, and each of the hard drives was the size of a dishwasher.
But I still have a similar reaction to the whole 50 year thing, until I remember that fifty years ago I was a couple of years out of high school...
Semper, don't feel bad. I'm of an age that when I think "50 years ago" I think World War One, not Vietnam. Now World War One is 100 years ago and 'Nam is 50!
If someone says "50-year-old airplane" to me the first thing that pops in my mind is a Sopwith Camel. Now it should be an F4 Phantom! Jeez!
When did THAT happen?
Just to prove my age... I saw "50 years ago" and was excited I was going to get to see some steam locos... OUCH! All dismals! {Face palm}
But, I did get to travel down nostalgia lane looking at the punch cards, mag tape, Teletypes, paper tape and computers with lots and lots of lights that blink!
Semper Vaporo
Pkgs.
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