Antique high-frequency alternating current generator (electric, player, antenna, audio)

[Tantalust]

Invented by Ernst Alexanderson, Sweden, 1904.
Built by GE.
200kW.
Replaced by vacuum tubes during the 1920s.

I love this stuff.




https://youtu.be/-S6gXmElHoI?t=167


https://en.wikpedia.org/wiki/Alexanderson_alternator

[plwhit]

They sure don't build them like they used to...

[timfountain]

I'd question the term High Frequency. The wiki article you linked states that it was a VLF transmitter in the 20KHz range. That's audio (for a dog or bat!). Very interesting none the less. Disclosure - I work on modern RF systems from 10Mhz to 72Ghz....

[harry chickpea]

Interesting, because it explores the limitations of electro-mechanical devices. The low end of the AM broadcast band is 550 Khz and these struggled to reach 100 Khz.

[Dude111]

Originally Posted by Tantalust

Replaced by vacuum tubes during the 1920s.

Yup tubes were quite good werent they??

[Tantalust]

Ya gotta love the exhaust fans just for the contactors!

[Tantalust]

A lot of tech guys back then must have been left hanging in the breeze after tubes quickly assumed control. Talk about a whole new ball of wax..

[PacoMartin]

Originally Posted by timfountain

I'd question the term High Frequency. The wiki article you linked states that it was a VLF transmitter in the 20KHz range. That's audio (for a dog or bat!). Very interesting none the less. Disclosure - I work on modern RF systems from 10Mhz to 72Ghz....

Wiki says radio waves as low as 3kHz exist. But yes the wavelength @ 20 khZ is 9.31 statute miles. I wonder what an antenna looked like?

[poppunk]

Originally Posted by PacoMartin

Wiki says radio waves as low as 3kHz exist. But yes the wavelength @ 20 khZ is 9.31 statute miles. I wonder what an antenna looked like?

This is a pretty common VLF antenna (this one is from 1922):





Even these massive antennas are electrically short and inefficient, which is why you see transmitters on the order of 1 megawatt at VLF frequencies.

[poppunk]

Originally Posted by timfountain

I'd question the term High Frequency. The wiki article you linked states that it was a VLF transmitter in the 20KHz range. That's audio (for a dog or bat!). Very interesting none the less. Disclosure - I work on modern RF systems from 10Mhz to 72Ghz....

That's an audio frequency, but an acoustic wave and a electromagnetic wave are two different things. We couldn't hear an EM wave at 3 kHz, otherwise we'd all be hearing the carriers for long range tactical submarine communications.