A couple of days ago, I stumbled upon this article:
"The WLW 500-kilowatt broadcast transmitter", Proceedings of the Institute of Radio Engineers volume 22, number 10, October 1934, pages 1151...1180.
The transmitter was amplitude-modulated by varying its supply voltage. A 350 kW audio amplifier was used for that. It consisted of two 175 kW amplifiers in parallel, so the show could go on with less modulation if one of them happened to break down.
The output stage of each of the two amplifiers had four valves type UV 862, a water-cooled valve of about 1.52 m (5 feet) height. The supply voltage was 11.8 kV. Each output transformer had a weight of 19 ton.
I read it via the IEEE site, but you can also find it here:
https://worldradiohistory.com/Archive-IRE/30s/IRE-1934-10.pdf
"The WLW 500-kilowatt broadcast transmitter", Proceedings of the Institute of Radio Engineers volume 22, number 10, October 1934, pages 1151...1180.
The transmitter was amplitude-modulated by varying its supply voltage. A 350 kW audio amplifier was used for that. It consisted of two 175 kW amplifiers in parallel, so the show could go on with less modulation if one of them happened to break down.
The output stage of each of the two amplifiers had four valves type UV 862, a water-cooled valve of about 1.52 m (5 feet) height. The supply voltage was 11.8 kV. Each output transformer had a weight of 19 ton.
I read it via the IEEE site, but you can also find it here:
https://worldradiohistory.com/Archive-IRE/30s/IRE-1934-10.pdf
Another high power transmitter that I was lucky to see closely, was cooled by steam. It was said to be more effective than water, and 100 or 150°C was cool enough for the tubes.
At the Antique Wireless Association museum in Bloomfiles NY, we display a decommissioned 250,000W transmitter from the Voice of America. The modulator was 125 KW, using vapor-cooled tubes - each one sat in a pot of water, with heat carried off by steam.
https://www.antiquewireless.org/wp-...-1-250000-watt-transmitter-scaled-300x225.jpg
https://www.antiquewireless.org/wp-...-1-250000-watt-transmitter-scaled-300x225.jpg
Due to the enormous vapourizing energy of water, vapour cooling @ normal atmospheric pressure by far is the most effective way to get rid of excessive heat. I know of several German stationary diesel engines of the pre war aera that are also cooled this way. Here, as an example, the DEUTZ MAH 711:
Best regards!
Just imagine Canada having to say "Could Y'all cut that down a little at night? Please?"
They eventually agreed to reduce power at night when it was not needed.
Just imaging how big of a deal it was at the time to have a radio station that could reach most of the US. Those commercial spots were worth a bundle.
They eventually agreed to reduce power at night when it was not needed.
Just imaging how big of a deal it was at the time to have a radio station that could reach most of the US. Those commercial spots were worth a bundle.
Those tubes will survive EMP generated during a nuclear war, as long as they're not destroyed from the initial blast.
https://www.theculturecrush.com/feature/conmen-at-the-border I don't think anyone actually knew how much power XERF broadcast back in the day.
Kay Pininha, I have a friend with a Hit-or-Miss engine from the 20s or 30s, which is about 50% larger than that Deisel. It starts with gasoline and then is run on kerosene. It uses a spark plug with an "ignition lighter", not an ignition coil but a low voltage variant to create a low voltage spark. It also is prone to pre-ignition when running hot under load, so a water injection system is incorporated to cool the head, and prevent carbon buildup.
With 8 cm bore, 11 cm stroke, calculating to a displacement of 553 cm³, a power of 6 hp@1500 min-1, that MAH 711 diesel really isn't a big engine. But, weighing about 150 kg, it's a massive one 😉 .
Best regards!
Best regards!
I remember reading about a pre-WWII era German 1MW transmitter, Nikola Tesla got a lot of people to broadcast at the same (about 14 MHz) frequency, creating a Tesla Hole or Gap in the spectrum. I think it was in 1936.
My memory is hazy, and a quick net search was futile.
The cable from transmitter to antenna was about 1 meter diameter, possibly water cooled, and they had problems with peasants using the power for free.
If anybody can chime in about this, I will be very glad.
My memory is hazy, and a quick net search was futile.
The cable from transmitter to antenna was about 1 meter diameter, possibly water cooled, and they had problems with peasants using the power for free.
If anybody can chime in about this, I will be very glad.
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Yes, in his 1934 book »Du und die Elektrizität« (You and electricity) German author Eduard Rhein writes about people who illuminated their gardens located next to a powerful radio transmitter station by that free RF energy.
Best regards!
Best regards!
Quite interesting- A good bit of history... and so preserved here
It's a two stroke diesel, isn't it? Well, in this case I'd rather regard a hot bulb engine as adequate for real men 😉 :
Best regards!