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Post AZDNeeelv0psd25SUq by [email protected] |
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Post #AZDNedizNqcBjp3JQm by [email protected] |
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did you know that 100 years ago there were *electromechanical* radio transmitte… |
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Post #AZDNednx5OaJzDNHAO by [email protected] |
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it started in the late 1800s, people were trying to build generators to power h… |
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Post #AZDNedsCpZzICPMfnU by [email protected] |
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but Professor Elihu Thomson and a certain Mr. Tesla (yes, *that* Tesla) figured… |
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Post #AZDNedwSZlOGPbM4Qa by [email protected] |
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see, a alternator's output frequency depends on 2 things: how fast it turns… |
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Post #AZDNee0iJwnEcnLT3g by [email protected] |
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the Thomson/Tesla design was a bit brute force in that way, so it quickly ran i… |
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Post #AZDNee4y48CCpzKrgm by [email protected] |
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then a guy named Alexanderson came along. he had some experience with the very … |
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Post #AZDNee9DoJbB3BKGJs by [email protected] |
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he lightened up the rotor (the rotating part of the alternator), streamlining i… |
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Post #AZDNeeD7ZoiZFH9NOi by [email protected] |
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here's a cross section of the concept. the rotor shaft (not shown) would be… |
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Post #AZDNeeH1LJpxRMyUTY by [email protected] |
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so now the maximum frequency is controlled mainly by the speed and the number o… |
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Post #AZDNeeKv6oxLdSnbYO by [email protected] |
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the next big problem that Alexanderson had to solve was controlling the speed. … |
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Post #AZDNeePAr0MJqen0BU by [email protected] |
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the saturation coil works by using a DC control current to push what is basical… |
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Post #AZDNeeT4cVTi2kc7GK by [email protected] |
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the next problem was to *modulate* the signal with morse code. for that, Alexan… |
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Post #AZDNeeWyO0b6EqRELA by [email protected] |
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the resulting transmit power was 200 kilowatts! even by modern standards this i… |
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Post #AZDNeeaWApQuPq63rk by [email protected] |
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(the frequency was quite a bit below standard AM broadcast, typically around 15… |
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Post #AZDNeeelv0psd25SUq by [email protected] |
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incredibly, there is still an *operational* Alexanderson transmitter! it is cal… |
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Post #AZDNeevQv4ABShslSy by [email protected] |
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there are so many cool details to this technology i had to leave out. but watch… |
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Post #AZDNefLfLX9Am49iM4 by [email protected] |
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the facility also has an informative website: https://grimeton.org/ |
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Post #AZDNeffAB2k7kXHHkG by [email protected] |
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and if you can't make it out to Sweden, there are virtual tours available: … |
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Post #AZDNefyJ1s3UhuEZaC by [email protected] |
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for further reading, here's a useful paper. https://www.navy-radio.com/xmtr… |
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Post #AjnAMUDfcPAF7cnsxc by [email protected] |
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@tubetime apparently someone made a modern receiver out of relatively equivalen… |
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Post #AvhCWLBub1H0jxskpE by [email protected] |
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@tubetime The one in Sweden is still working. They run it ~2 times a year. On n… |
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Post #AvhCa8AyvZA7X8FpVA by [email protected] |
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@tubetime (and those 500 kW AM stations only operated on an experimental basis;… |
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Post #AvhCbq8UyG9wA7uLLc by [email protected] |
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@tubetime somebody heared about the Test QSO of #SAQ ?Today in Erfurt with lon… |
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Post #AvhCbqGeTwgIZPir3Y by [email protected] |
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@tubetime the schedule is here:https://alexander.n.se/en/celebrate-100-years-wi… |
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Post #AvhCgOdmcqkAKoiJGK by [email protected] |
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@tubetime There are 400 kW AM transmitters now that are completely solid-state,… |
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Post #AvhCgbtVLi2lRLAY4W by [email protected] |
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@tubetime I saw the image and instantly thought "Grimeton!" 😆 glad… |
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Post #AvhCkZRKPtfqzBsWJ6 by [email protected] |
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@tubetime Fun times. Now I'm thinking about one of those spinning disks of … |
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Post #AvhCkZYlyDd3MHMSuW by [email protected] |
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@tubetime Since this is getting attention again, I'll mention that seeing t… |
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Post #AvhCr4DQuD0yAnTc6C by [email protected] |
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@tubetime Remarkably similar to a Fisher and Paykel washing machine motor which… |
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Post #AvhCr4LaPtXKa5I7o8 by [email protected] |
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@zl2tod so no spin cycle? |
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Post #AvhCr4Rc3UMCsm6wCW by [email protected] |
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@crazor Yeah, it's fast enough for spin.Some say they do 1400rpm.That's… |
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Post #AvhCrCucZWJZ93kDWi by [email protected] |
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@tubetime Oh that's pretty close to me!Have thought about visiting it a cou… |
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Post #AvhCwj9K8tHmZhFmvQ by [email protected] |
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@tubetime I thought even at 100 kW, you start getting spooky effects like nearb… |
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Post #AvhCwjGlhDEywmjjWq by [email protected] |
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@cr1901 @tubetime I remember back in the late 80s my Telecom Australia apprenti… |
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Post #AvhCwlG8IXv97OSFoe by [email protected] |
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@mpcnat Hah! I got to experience that at the 3LO transmitters in Melbourne. A… |
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Post #AvhCz15gPMkOnWdsxs by [email protected] |
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@tubetime Does that mean it accidentally uses frequency-shift keying? |
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Post #AvhCzPF4c6WFhbDivw by [email protected] |
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@tubetime I LOVE machinery. I am a retired auto technition |
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Post #AvhD0b0QMUlqTaw4NE by [email protected] |
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@tubetime Thanks for posting this; on my list for my next visit to Scandinavia. |
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Post #AvhD2mKHFDrkAGGKYq by [email protected] |
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@tubetime OMG the air-quenched relays are scary, and they're just right out… |
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Post #AvhD2pA6hUVsxaWkcq by [email protected] |
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@tubetime Also *that* Thomson. The Thomson-Houston Electric Company was one of … |
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Post #AvhD2pHCH8BVJZqPg0 by [email protected] |
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@wollman ahhh i had a tickle of memory that he was a famous thomson but i forgo… |
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Post #AvhD7Wl2YRxnKP2r5s by [email protected] |
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@elithebearded @tubetime Mechanical signal generation technology extended to th… |
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Post #AvhDAzCPGb0cPFUjSa by [email protected] |
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@tubetime aka #Rundfunk |
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Post #AvhDEUCaSH5hQeFRMu by [email protected] |
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@tubetime So freaky electrical fact: some of those arc lights were series circu… |
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Post #AvhDIL4iKZnqHRP1mK by [email protected] |
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@tubetimeI knew some of that, but not in the detail you posted. Thanks Tubey! |
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Post #AvhDLlOYvhe8mOJs9I by [email protected] |
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@tubetime OMG it runs off 2-phase because the motor that drives it is from a ve… |
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Post #AvhDQ0aiNCdZ4F1n6W by [email protected] |
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@tubetime Great thread, thanks! |
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Post #AvhDQ8fyJXb08rY6PQ by [email protected] |
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@tubetime Okay, this is wild, I had no idea. https://en.wikipedia.org/wiki/Grim… |
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Post #AvhDTioUPeJl5ZF2VU by [email protected] |
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@tubetime Beautiful thread! |
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Post #AvhDTzwYitsEDW9Dwe by [email protected] |
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@selea @tubetime Tomorrow July 2 is the 100 year anniversary of Grimeton.https:… |
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Post #AvhDXtyMrf72rCr5MW by [email protected] |
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@bornach @tubetime For me at least, spinning disk is very easy to understand ev… |
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Post #AvhDdypBjomDduSZtY by [email protected] |
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@tubetimeWow what a beast 😲 Great video there! |
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Post #AvhDgKnT169OMqmGTw by [email protected] |
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@tubetime fascinating |
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Post #AvhDm3R4TiAeGC1tMO by [email protected] |
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@tubetime And when Fessenden broadcast voice in 1906, he just wired a carbon mi… |
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Post #AviLTWZauntruxeRI8 by [email protected] |
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@SM0RVV They run it today too :)@tubetime |
