...and also for real women. Please kindly watch this young, petite and smart lady starting and operating an Italian Landini L55, also a two stroke, hot bulb powered tractor 😉 :
Best regards!
Best regards!
There are some photos of those enormous output tubes here: http://theradiohistorian.org/wlwgallery1/wlwgallery1.html
Someone from a Dutch audio forum found this film with a tour of what is left from the transmitter - including some output valves and one of the modulator output transformers
As Laurens Hammond still was to invent his famous organ in 1934, I wonder which organ can be seen in this pic from 1924?
Best regards!
It looks like a theater organ console, maybe a Wurlitzer. The body of the organ could be behind the curtains.
Did Wurlitzer build pipe organs then? Or on which principle did their organs work?
Best regards!
Best regards!
Yes, it was the leading manufacturer of a peculiar pipe organ designed to play the original score of silent movies. It works at higher air pressure compared to church organs to better emulate the brass section of the orchestra and had a few special registers and effects. This video (also available in german) explains the instrument:
Classic AM transmitters used "brute force" plate modulation needing clean Audio 50% trasmitter power amplifiers, which meant not only bigb tubes but also monster modulation OTs ... which to boot had to stand huge DC idle current, whatever the transmitter took.
A few cheapies used screen modulation, but were typically only 35% efficient.
When I was starting Electronics, late 60s early 70s , a couple 100kW AM broadcast radio stations were built here in Argentina, using a new RCA invention: to avoid the monster Modulation Transformer, they used two exact same 50kW transmitters , one of them was RF phase modulated with Audio program against the other (which was left unmolested and stable) , both feeding the same antenna.
RF output varied from 2X (when in phase) to zero (out of phase) , achieving perfect 100% AM modulation.
They did not save on tubes or power, but certainly saving on a couple Ton MT was good 🙂
A few cheapies used screen modulation, but were typically only 35% efficient.
When I was starting Electronics, late 60s early 70s , a couple 100kW AM broadcast radio stations were built here in Argentina, using a new RCA invention: to avoid the monster Modulation Transformer, they used two exact same 50kW transmitters , one of them was RF phase modulated with Audio program against the other (which was left unmolested and stable) , both feeding the same antenna.
RF output varied from 2X (when in phase) to zero (out of phase) , achieving perfect 100% AM modulation.
They did not save on tubes or power, but certainly saving on a couple Ton MT was good 🙂
This 500 kW transmitter used a kind of parafeed structure. A 50 uF, 15 kV capacitor and a choke with a weight of 12 ton kept the RF amplifiers' DC currents out of the modulator output transformers.
The RF power on some Soviet aircraft was also remarkable, I read 600 kW on MiG-25R.
That implies a generator rated at almost 2 MW.
It seems it could kill rabbits on the runway, the pilots were instructed to switch on the radar once airborne.
Could be a tall story, or my memory is playing tricks...the optics were also famous, as used in the cameras.
That implies a generator rated at almost 2 MW.
It seems it could kill rabbits on the runway, the pilots were instructed to switch on the radar once airborne.
Could be a tall story, or my memory is playing tricks...the optics were also famous, as used in the cameras.
That’s probably EIRP, with much of the gain coming from the antenna. And average power much lower, as you can’t talk and listen at the same time. Still a lot of power focused in a tight beam, which might still be rabbit-sized at the end of the runway.
On a ship it might approach 600 kW of average power since there is enough coolant available to do it, and they DO need to be able to sense the enemy with enough warning time to get the birds in the air. The stories about fried seagulls are quite real.
On a ship it might approach 600 kW of average power since there is enough coolant available to do it, and they DO need to be able to sense the enemy with enough warning time to get the birds in the air. The stories about fried seagulls are quite real.
I think such waste of energy like e.g. the 1MW (!) 540 kHz AM transmitter in Hungary is insane. But it was built because of a well known political background, more on it is against the forum rules, I believe.
Fact is every household had a simple AM receiver. SW receivers were not so common, the receiver was more expensive, and it was against politics to be able to listen to every kind of foreign news. 50's, 60's behind the Iron Curtain was the era when big AM transmitters were built.
Fact is every household had a simple AM receiver. SW receivers were not so common, the receiver was more expensive, and it was against politics to be able to listen to every kind of foreign news. 50's, 60's behind the Iron Curtain was the era when big AM transmitters were built.
Radar and Jamming is all about pulse power and narrow beams, really really short pulses;
actually the shorter the pulse, the higher the radar's resolution;
the 600kW is likely to be the peak pulse power in the center of the beam, while average power may be orders of magnitude lower.
Pulse energy is stored in high voltage capacitor banks for that purpose.
High voltages also produced massive amounts of hard x-rays, and there were reports that many military repair men died of radiation induced cancer 10 or 20 years after; they had to repair, test and calibrate radar equipment with doors and shields down.
Here's a more modern example of a 500kW SW transmitter from 1972:
Two of these YL1490 tubes were run in parallel to produce the RF power, while another pair of the same type in push-pull served as modulation amplifier.
The 12kV power supply however was already SS and had thyristors in the rectifier bridge.
The article's author also mentioned that the modulation transformer was in a separate cabinet due to its weight and or safety reasons, but unfortunately there was no picture shown ...
also there is a datasheet of the YL1490 tube ... Coaxial metal-ceramic tetrode, vapor-cooled, with integrated boiler .
Two of these YL1490 tubes were run in parallel to produce the RF power, while another pair of the same type in push-pull served as modulation amplifier.
The 12kV power supply however was already SS and had thyristors in the rectifier bridge.
The article's author also mentioned that the modulation transformer was in a separate cabinet due to its weight and or safety reasons, but unfortunately there was no picture shown ...
also there is a datasheet of the YL1490 tube ... Coaxial metal-ceramic tetrode, vapor-cooled, with integrated boiler .
Audio transformer design article for this system.
https://dalmura.com.au/static/High Power Audio Transformers.pdf
https://dalmura.com.au/static/High Power Audio Transformers.pdf
What a great thread! It brings out our (lost?) childish ability to be amazed. We're all too jaded, and don't try to deny it, it's natural.
Much thanks to all,
Chris
Much thanks to all,
Chris
