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Sententia
2010-Jun-07, 03:43 PM
I just got done reading an article about a radio playing old tunes from the 40's , and even wartime speeches from Winston Churchill. It's a wireless radio, and before I dismissed it I became curious. In our world of understanding physics- is this possible and how would it be ? Could a 70 year old radio pick up these old wave frequencies and broadcast them without receiving any power for decades ? The more I think about it, the more I view it as a tourist ploy but it raises the question. I don't understand how energy is harnessed and released or frequencies stored so I'm just asking the science and techies what they think.

the radio

http://img.thesun.co.uk/multimedia/archive/01058/SNA051911-682_1058433a.jpg
(Mod note: image shows two antiques, one holding the other's severed power connection)

link to article http://www.thesun.co.uk/scotsol/homepage/news/3001039/Wartime-radios-got-us-spooked.html

mike alexander
2010-Jun-07, 04:14 PM
That sounds as close to impossible as anything I can think of. The story reminds me of a Twilight Zone teleplay from 1960 called "Static". (http://en.wikipedia.org/wiki/Static_(The_Twilight_Zone)).

NEOWatcher
2010-Jun-07, 04:57 PM
link to article http://www.thesun.co.uk/scotsol/homepage/news/3001039/Wartime-radios-got-us-spooked.html
"The Sun" says a lot to me. :wall:

If it's in a museum, then is it entirely possible there is some background music somewhere, or within another exhibit that just happens to fit the accustics where this radio sits? Maybe they can here the same thing from a rock if they placed it there.

On the humorous side of the article:
If it's a wireless, then what's he doing holding a wire in the picture? (it's a joke people, don't jump on it)
So if Winnie, and Glenn are dead, I guess all the recordings are dead too. Right?

mugaliens
2010-Jun-09, 07:56 AM
"Air station secretary Peter David said: "There is a weird atmosphere at the base." "

I'll say...

TrAI
2010-Jun-11, 01:50 AM
I just got done reading an article about a radio playing old tunes from the 40's , and even wartime speeches from Winston Churchill. It's a wireless radio, and before I dismissed it I became curious. In our world of understanding physics- is this possible and how would it be ? Could a 70 year old radio pick up these old wave frequencies and broadcast them without receiving any power for decades ? The more I think about it, the more I view it as a tourist ploy but it raises the question. I don't understand how energy is harnessed and released or frequencies stored so I'm just asking the science and techies what they think.

the radio

http://img.thesun.co.uk/multimedia/archive/01058/SNA051911-682_1058433a.jpg
(Mod note: image shows two antiques, one holding the other's severed power connection)

link to article http://www.thesun.co.uk/scotsol/homepage/news/3001039/Wartime-radios-got-us-spooked.html

I would think it was possible for a radio to pick up some signal even without power, sure, the detector and amplifier circuits would not actually work as intended(tubes does not work without power, after all), but there still would be some passive electronics in there that might do something. If I recall correctly, one of the early forms of detector used an polarized electrolyte setup as a detector, so I wouldn't think it impossible that some old capacitor inside the thing could function in this way. The output wouldn't be very loud, i expect, but a weak, hard to make out sound would probably let the listener supply more to the pattern...

It is also conceivable someone is playing a joke on him. I should think.

Spoons
2010-Jun-11, 02:02 AM
This:

(Mod note: image shows two antiques, one holding the other's severed power connection)
made my day. Hilarious!

jlhredshift
2010-Jun-11, 02:41 PM
I would think it was possible for a radio to pick up some signal even without power, sure, the detector and amplifier circuits would not actually work as intended(tubes does not work without power, after all), but there still would be some passive electronics in there that might do something. If I recall correctly, one of the early forms of detector used an polarized electrolyte setup as a detector, so I wouldn't think it impossible that some old capacitor inside the thing could function in this way. The output wouldn't be very loud, i expect, but a weak, hard to make out sound would probably let the listener supply more to the pattern...

It is also conceivable someone is playing a joke on him. I should think.

As a kid I built a kit radio that was a long wire, single ear plug, and a crystal that you moved a wire around on and you could pick up signals. Got bored with that pretty fast, couldn't hold the wire in the right place for any period of time.

Geo Kaplan
2010-Jun-11, 03:33 PM
I would think it was possible for a radio to pick up some signal even without power, sure, the detector and amplifier circuits would not actually work as intended(tubes does not work without power, after all), but there still would be some passive electronics in there that might do something. If I recall correctly, one of the early forms of detector used an polarized electrolyte setup as a detector, so I wouldn't think it impossible that some old capacitor inside the thing could function in this way. The output wouldn't be very loud, i expect, but a weak, hard to make out sound would probably let the listener supply more to the pattern...

It is also conceivable someone is playing a joke on him. I should think.

As jlhredshift noted, there are "zero power" radios (google "crystal radio"). These were developed a century ago, before amplifiers were invented. Because they are passive, the audio they produce is necessarily lower in power than that of the wireless signals they receive. To produce audible sound from a speaker would require rather substantial power received at the antenna.

Someone is obviously playing a joke.

captain swoop
2010-Jun-11, 04:06 PM
Maybe he was picking up the BBC. They have a lot of repeats.

kleindoofy
2010-Jun-11, 08:51 PM
... a radio playing old tunes from the 40's , and even wartime speeches from Winston Churchill. ...
That's what I love so much about all these stupid woo things.

Wartime speeches from Winston Churchill? He only made a few, so it's funny that the radio would just happen to pick up those very few minutes of broadcasting instead of the countless hours of normal blah blah. How stupid can it get?

It reminds me of those geneology freaks who spend lots of money searching for their ancestors, totally certain that they themselves are of noble origin. No, they're not. They come down from the 99,99% of possessionless, landless servants and serfs, just like the rest of us. Take the coat of arms off the wall, dumbo! It's not yours.

Not to mention reincarnationists. No, you weren't Napoleon. No, you weren't an important revolutionary monk. Even if there were such a thing as reincarnation, you would only find out that you were a poor slob who died at thirty with no teeth left after working 18 hours a day for 24 years for some tyrannic farmer.

HenrikOlsen
2010-Jun-11, 09:03 PM
It reminds me of those geneology freaks who spend lots of money searching for their ancestors, totally certain that they themselves are of noble origin. No, they're not. They come down from the 99,99% of possessionless, landless servants and serfs, just like the rest of us. Take the coat of arms off the wall, dumbo! It's not yours.
The other side to the coin of geneologist are those who research it out of a genuine interest in whichever ancestors they have, and a love for the puzzle of getting the records to fit together. My father's one of those.
Incidentally, he linked us to royalty twice and found the link to not be correct on further study. I think the current state of knowledge is that we aren't linked.

On the other hand, a rather large amount of the ancestors found were amongst those tyrannic farmers:D

cjameshuff
2010-Jun-11, 11:42 PM
I would think it was possible for a radio to pick up some signal even without power, sure, the detector and amplifier circuits would not actually work as intended(tubes does not work without power, after all), but there still would be some passive electronics in there that might do something. If I recall correctly, one of the early forms of detector used an polarized electrolyte setup as a detector, so I wouldn't think it impossible that some old capacitor inside the thing could function in this way. The output wouldn't be very loud, i expect, but a weak, hard to make out sound would probably let the listener supply more to the pattern...

It is also conceivable someone is playing a joke on him. I should think.

Note that old radios like that predated cheap, strong, compact permanent magnets. The loudspeaker often used an electromagnet instead of a permanent magnet, and so required a fair bit of power to operate at all. Crystal sets generally used earphones instead...the older ones being moving-iron devices that were relatively sensitive, but incapable of much power.

It's possible someone's playing a prank on him, it's also possible it's just wishful thinking. The ear is good at picking out patterns from noisy signals. I wouldn't be surprised if it's just something similar to the distortion of ambient noise that occurs when you hold a seashell to your ear, combined with him trying to hear old radio programs.

Geo Kaplan
2010-Jun-12, 12:01 AM
That's what I love so much about all these stupid woo things. {snip}

Not to mention reincarnationists. No, you weren't Napoleon. No, you weren't an important revolutionary monk. Even if there were such a thing as reincarnation, you would only find out that you were a poor slob who died at thirty with no teeth left after working 18 hours a day for 24 years for some tyrannic farmer.

Yes -- it's funny how no one says, "I was a janitor in a Roman vomitorium." They were invariably someone much more interesting.

Gillianren
2010-Jun-12, 06:04 PM
The other side to the coin of geneologist are those who research it out of a genuine interest in whichever ancestors they have, and a love for the puzzle of getting the records to fit together. My father's one of those.

Both my grandfathers were. I have a lot of genealogical data.


Incidentally, he linked us to royalty twice and found the link to not be correct on further study. I think the current state of knowledge is that we aren't linked.

On the other hand, a rather large amount of the ancestors found were amongst those tyrannic farmers:D

I'm not sure if we have any, but we have Scots ancestry. We can display the stuff because we were part of the clan. Ireland, I believe, works similarly. Either way, though, odds aren't bad that any given one of us is descended from Genghis Khan, even if pretty much all the ancestors past that point were peasants.


Yes -- it's funny how no one says, "I was a janitor in a Roman vomitorium." They were invariably someone much more interesting.

Than a stadium janitor? Yeah. (The "vomitorium" wasn't as gross as it sounds. It was the exits on the stadia, the place where people came forth.) Though, to the credit of Boopsie from Doonesbury, she once referred to a previous incarnation as "the first one in ages where I didn't die in childbirth."

captain swoop
2010-Jun-12, 06:25 PM
Arnold Rimmer found out he was Alexander the Greats Chief Eunuch

ravens_cry
2010-Jun-12, 07:00 PM
Ah the Eunuch. Men prized for what they couldn't do. :p

Geo Kaplan
2010-Jun-12, 09:16 PM
Than a stadium janitor? Yeah. (The "vomitorium" wasn't as gross as it sounds. It was the exits on the stadia, the place where people came forth.) Though, to the credit of Boopsie from Doonesbury, she once referred to a previous incarnation as "the first one in ages where I didn't die in childbirth."

:)

JohnD
2010-Jun-12, 10:18 PM
Sententia,
I think you canot live in the UK, else you would know the Sun newspaper.
It purposely uses a vocabulary of about 600 words, and prints a picture on page three every day of a naked woman. It would print it on page one, but then it would be relegated to the top shelves, with "Readers Wives". Interestingly, the owner of the latter journal has recently said he wants to buy the Sun, but Rupert Murdock knows where the money is.

The Sun is an archetypical UK "red-top" newspaper that panders to a sensational form of journalism, described I think in the US as 'yellow'.
It is NOT a 'paper of record'.
I'd suggest that you don't waste your time reading anything form there, unless you wish to measure the lowest common denominator of society.

Yours, very snobbishly,
John

TrAI
2010-Jun-13, 04:12 PM
As a kid I built a kit radio that was a long wire, single ear plug, and a crystal that you moved a wire around on and you could pick up signals. Got bored with that pretty fast, couldn't hold the wire in the right place for any period of time.


As jlhredshift noted, there are "zero power" radios (google "crystal radio"). These were developed a century ago, before amplifiers were invented. Because they are passive, the audio they produce is necessarily lower in power than that of the wireless signals they receive. To produce audible sound from a speaker would require rather substantial power received at the antenna.

Someone is obviously playing a joke.

Well, yes, I do know about crystal radios, however, I was describing another technology, the electrolytic detector.

From the picture, it doesn't seem likely that the sound is very loud, he is practically holding his ear against the speaker.


Note that old radios like that predated cheap, strong, compact permanent magnets. The loudspeaker often used an electromagnet instead of a permanent magnet, and so required a fair bit of power to operate at all. Crystal sets generally used earphones instead...the older ones being moving-iron devices that were relatively sensitive, but incapable of much power.

It's possible someone's playing a prank on him, it's also possible it's just wishful thinking. The ear is good at picking out patterns from noisy signals. I wouldn't be surprised if it's just something similar to the distortion of ambient noise that occurs when you hold a seashell to your ear, combined with him trying to hear old radio programs.

Good point, speakers with field coils would be common in radios from the 1930s and into the 40s, And these would need a field current to work. Come to think about it, permanent magnet speakers of the time may very well have lost some magnetic field strength by this time, and not be able to make much sound this way.

Still, it is hard to say anything definite from that story, but it is not likely to be haunting or some sort of time traveling signal, at least. ;)

Spoons
2010-Jun-14, 12:14 AM
From the picture, it doesn't seem likely that the sound is very loud, he is practically holding his ear against the speaker.

Mind you, that's a photo for the article. Not a fish-eye shot either, so how far could he realistically stand from it and still get the right sort of photo. That said, I imagine it to sound fairly dim too - like when you can hear something throuigh a wall. Suspiciously like that.

Geo Kaplan
2010-Jun-14, 04:43 AM
Well, yes, I do know about crystal radios, however, I was describing another technology, the electrolytic detector.

It makes no difference. Both are passive devices, so the received power necessary to produce an audible output remains extremely high. That, in turn, implies either a local source of the transmission, or hidden active electronics.

HenrikOlsen
2010-Jun-14, 11:05 AM
Mind you, that's a photo for the article. Not a fish-eye shot either, so how far could he realistically stand from it and still get the right sort of photo. That said, I imagine it to sound fairly dim too - like when you can hear something throuigh a wall. Suspiciously like that.
Are you thinking what I'm thinking?

Given that it's an exhibition which has things from that time, could another exhibit be showing period radio casts? And that's what was heard?

Spoons
2010-Jun-14, 11:19 AM
The radio is kept in a 1940s museum at the airbase, ...

Well, it's at a museum. I would think that's the first thing anyone would expect if they hear it's occurred at a museum. You know, the sort of place with a bunch of exhibitions. Firing off tales of history. Songs of the era. The great speeches.


...which is rumoured to have several ghosts - including a dog and a pilot.

Oh, well then I take it back. Clearly it's ghosts doing mocking SCARE-casts!

ZOINKS SCOOB! LIKE, LET'S SCRAM!

RYEAH! REAH! Hee hihihiheehihiheeeee!

neilzero
2010-Jun-14, 11:39 AM
As a teenager, I had two radios from about 1930 The older one had a permanent magnet speaker, that still worked in 1950. The field coil speaker also produced some sound even with no current flowing in the field coil.
I remember that twilight zone episode which likely inspired the recent hoax. Neil

TrAI
2010-Jun-15, 12:43 AM
Mind you, that's a photo for the article. Not a fish-eye shot either, so how far could he realistically stand from it and still get the right sort of photo. That said, I imagine it to sound fairly dim too - like when you can hear something throuigh a wall. Suspiciously like that.

Sure, it is probably a staged photo, but it may still be indicative of the sound not being very strong.


It makes no difference. Both are passive devices, so the received power necessary to produce an audible output remains extremely high. That, in turn, implies either a local source of the transmission, or hidden active electronics.

It would have to be high relative to an active receiver, but there is no inherent problem with that, there may very well be radio transmitters in the area, or close enough to get a reasonably strong signal. And seeing as this is a former air-force base, and an air-force museum, it is quite possible that the equipment necessary is available very close by.

Geo Kaplan
2010-Jun-15, 03:34 AM
Sure, it is probably a staged photo, but it may still be indicative of the sound not being very strong.



It would have to be high relative to an active receiver, but there is no inherent problem with that, there may very well be radio transmitters in the area, or close enough to get a reasonably strong signal. And seeing as this is a former air-force base, and an air-force museum, it is quite possible that the equipment necessary is available very close by.

The numbers don't work out, unfortunately. Let's say that you need to get 100mW to the speaker to make things reasonably audible. A passive device -- electrolytic or other diode-like thing -- will have a poor impedance match to a speaker, so the efficiency will be well below 1%. But let's be optimistic and say that it is as high as that. Then the power received has to be over 10W. With a small antenna (assumed because no one said "Hey, there's a gigantic antenna attached to this thing") the implied power densities are well beyond anything you could reasonably postulate. Think about how difficult it is to light up even small incandescent bulbs by wireless means, and that will give you and idea of how tough this problem is.

The best hypotheses are that the radio had a hidden source of power, or there was a hidden wire to the speaker, or something of that nature. A completely passive wireless explanation just doesn't work out.

DonM435
2010-Jun-15, 04:39 PM
...
Wartime speeches from Winston Churchill? He only made a few, so it's funny that the radio would just happen to pick up those very few minutes of broadcasting instead of the countless hours of normal blah blah.
...


I remember someone asking our physics teacher many years ago whether it would ever be possible to recover hitherto-unrecorded sounds from the past. No, he said, invoking spoilsport concepts like thermodynamics and entropy.

I wondered if, ten thousand years later, the scientist who actually does accomplish that would play back this long-dead professor's very words for comedic effect.

Geo Kaplan
2010-Jun-15, 07:38 PM
I remember someone asking our physics teacher many years ago whether it would ever be possible to recover hitherto-unrecorded sounds from the past. No, he said, invoking spoilsport concepts like thermodynamics and entropy.

I wondered if, ten thousand years later, the scientist who actually does accomplish that would play back this long-dead professor's very words for comedic effect.

Yes, it would be funny (actually, miraculous) if it were to happen, but it isn't going to, for the very reasons that the physics teacher gave. Without some sort of recording device, thermal and other noise processes quickly swamp out the signal as the sound waves propagate. In a very short time, the signal-to-noise ratio degrades to a level where recovery is, for all practical purposes, impossible. I wish it were otherwise!

TrAI
2010-Jun-16, 07:05 PM
The numbers don't work out, unfortunately. Let's say that you need to get 100mW to the speaker to make things reasonably audible. A passive device -- electrolytic or other diode-like thing -- will have a poor impedance match to a speaker, so the efficiency will be well below 1%. But let's be optimistic and say that it is as high as that. Then the power received has to be over 10W. With a small antenna (assumed because no one said "Hey, there's a gigantic antenna attached to this thing") the implied power densities are well beyond anything you could reasonably postulate. Think about how difficult it is to light up even small incandescent bulbs by wireless means, and that will give you and idea of how tough this problem is.

The best hypotheses are that the radio had a hidden source of power, or there was a hidden wire to the speaker, or something of that nature. A completely passive wireless explanation just doesn't work out.

hmmm... 100mW to the speaker, isn't that a bit extreme for this circumstance? After all, the sound is probably not that much stronger than what would be needed to hear it when next to the speaker, I would have said less than 10uW. You might be able to do with less, depending on noise and the hearing of the listener, as you only have to make it strong enough to be recognized as speech or music, the brain will fill in the rest. That this is a 40's radio, may also make the listener more likely to identify the sound as being from that time.

As for the antenna, well, there might be an internal wire coil long enough, and it really depends on the frequency of the recieved signal. A crystal radio for the FM band, for instance, would use an antenna that is less than 20cm.

Geo Kaplan
2010-Jun-16, 07:49 PM
hmmm... 100mW to the speaker, isn't that a bit extreme for this circumstance? After all, the sound is probably not that much stronger than what would be needed to hear it when next to the speaker, I would have said less than 10uW. You might be able to do with less, depending on noise and the hearing of the listener, as you only have to make it strong enough to be recognized as speech or music, the brain will fill in the rest. That this is a 40's radio, may also make the listener more likely to identify the sound as being from that time.

As for the antenna, well, there might be an internal wire coil long enough, and it really depends on the frequency of the recieved signal. A crystal radio for the FM band, for instance, would use an antenna that is less than 20cm.

Nice try, but still no go. To see why this type of hypothesis must be abandoned altogether, let's do more calculations.

Let's provisionally assume that your figure of 10uW acoustic power is consistent with audibility. It does help to know that speakers of that era were perhaps 1% efficient at converting electrical power to acoustic power, but let's be generous and call it 10%. So, we're talking about needing to deliver about 100uW to the electrical terminals of the speaker.

Typical speakers have impedances in the sub-20-ohm range (8 and 16 ohm values were common then). Let's call it 10 for the purposes of our calculations to keep the numbers simple. Crystal detectors typically have impedances in the 10-100kilohm range (and we're making the generous assumption that the radio in question uses a crystal detector; this is not actually the case). So, of the power delivered to the detector, somewhere between 10ppb and 1ppm makes it to the speaker. Working backwards, that means that the antenna system has to deliver between 100W and 10kW to the detector. Pause and reflect on those magnitudes for a moment.

Assume what you want about the efficiency of coupling antenna power to the detector, and you quickly see that there are far too many orders of magnitude to span the gap. Do you now see why a passive scenario is completely absurd? The required RF field strengths would be so large as to cause spontaneous arcing among metal components.

As for your FM hypothesis, there are at least two significant problems that make the scenario worse, not better. First, a crystal detector does not demodulate FM particularly well (you can do it, by a process known as slope detection, but it degrades sensitivity even further). More seriously, FM broadcast radio did not exist in the UK at the time that the Pye radio was built.

In summary, the best hypotheses remain what I said earlier: There is a hoax going on, in which either the report is fabricated, or the radio actually has a source of power, or is not in fact wirelessly operated. Given the reputation of that publication, the hoax hypothesis looks like a strong contender.


ETA: If we are to infer from the article that the radio is otherwise unmodified, then it is important to recognize that unpowered tubes/valves do not convey signals very well. Whatever power is received by the antenna will have a tough time getting to the detector at all.

It's a hoax/joke/gag.

Jeff Root
2010-Jun-17, 04:49 PM
I had a reel-to-reel tape recorder made circa 1967 that, after a few
years of use, started picking up a radio station while it was turned on.
I don't remember if I was able to identify the station, but it was clearly
one of those with a strong signal in my location. The main point: The
sound did not come out of the tape recorder's speaker. It came from
the electronics.

Also, my friend has a tooth filling which detects radar, like police radar,
although only in the older band (K-band, maybe?) that isn't used much
anymore. I've been with him a couple of times when he announced
that there was a radar aimed at us.

-- Jeff, in Minneapolis

LotusExcelle
2010-Jun-17, 05:05 PM
I had a reel-to-reel tape recorder made circa 1967 that, after a few
years of use, started picking up a radio station while it was turned on.
I don't remember if I was able to identify the station, but it was clearly
one of those with a strong signal in my location. The main point: The
sound did not come out of the tape recorder's speaker. It came from
the electronics.

Also, my friend has a tooth filling which detects radar, like police radar,
although only in the older band (K-band, maybe?) that isn't used much
anymore. I've been with him a couple of times when he announced
that there was a radar aimed at us.

-- Jeff, in Minneapolis

Where did the sound come out of then?

Also to confirm he was detecting radar you would need to blind test him or even double-blind. I do not doubt that such things are possible but testing their validity is necessary.

kleindoofy
2010-Jun-17, 07:27 PM
Way back when, we had this really crazy thing. You had these black disks with squiggly grooves cut into them. If you ran a needle along the grooves, you could hear music from the past. Without electricity, it all sounded rather high pitched, but with electricity it sounded very authentic.

Just imagine!

Almost magic.

Geo Kaplan
2010-Jun-17, 07:43 PM
I had a reel-to-reel tape recorder made circa 1967 that, after a few
years of use, started picking up a radio station while it was turned on.
I don't remember if I was able to identify the station, but it was clearly
one of those with a strong signal in my location. The main point: The
sound did not come out of the tape recorder's speaker. It came from
the electronics.

Which were plugged in and turned on. Totally believable, and quite common.



Also, my friend has a tooth filling which detects radar, like police radar,
although only in the older band (K-band, maybe?) that isn't used much
anymore. I've been with him a couple of times when he announced
that there was a radar aimed at us.

-- Jeff, in Minneapolis

I'd like to meet/interview him. I've heard similar anecdotes, but never met anyone who was less than three degrees of separation from the one experiencing the phenomenon.

Geo Kaplan
2010-Jun-17, 07:44 PM
Way back when, we had this really crazy thing. You had these black disks with squiggly grooves cut into them. If you ran a needle along the grooves, you could hear music from the past. Without electricity, it all sounded rather high pitched, but with electricity it sounded very authentic.

Just imagine!

Almost magic.

I still think of it as pretty magical. I have a healthy collection of LPs, and it amazes me how such simple technology was nevertheless capable of quite good sound.

(And speaking of good sound, are you related to Ms. Hahn, or just a fan?)

KaiYeves
2010-Jun-18, 04:51 PM
Way back when, we had this really crazy thing. You had these black disks with squiggly grooves cut into them. If you ran a needle along the grooves, you could hear music from the past. Without electricity, it all sounded rather high pitched, but with electricity it sounded very authentic.

Just imagine!

Almost magic.

It is, isn't it?

TrAI
2010-Jun-21, 05:18 PM
Nice try, but still no go. To see why this type of hypothesis must be abandoned altogether, let's do more calculations.

Let's provisionally assume that your figure of 10uW acoustic power is consistent with audibility. It does help to know that speakers of that era were perhaps 1% efficient at converting electrical power to acoustic power, but let's be generous and call it 10%. So, we're talking about needing to deliver about 100uW to the electrical terminals of the speaker.

That was supposed to be electric, not acoustic power, the acoustic power would be somewhere in the 10nW-100nW range(if we assume a 0.1-1% speaker efficiency). If my memory serves me right, this would translate to the equivalent of 40-50dB beside the speaker. The human threshold of hearing is considered to be about 1pW/m2, or 0dB, but I think that would be rather unlikely in anything but perfect silence and the listener would probably have to have excellent hearing...


Typical speakers have impedances in the sub-20-ohm range (8 and 16 ohm values were common then). Let's call it 10 for the purposes of our calculations to keep the numbers simple. Crystal detectors typically have impedances in the 10-100kilohm range (and we're making the generous assumption that the radio in question uses a crystal detector; this is not actually the case). So, of the power delivered to the detector, somewhere between 10ppb and 1ppm makes it to the speaker. Working backwards, that means that the antenna system has to deliver between 100W and 10kW to the detector. Pause and reflect on those magnitudes for a moment.

Hmmm... Tube outputs would have a rather high impedance, so you would need to match the impedance in some way, There have been some sets designed with high impedance speakers, but they are not that common, generally an impedance transformer is used. It is hard to say without knowing what tubes were used in the radio, though somewhere in the thousands of ohms was common.


Assume what you want about the efficiency of coupling antenna power to the detector, and you quickly see that there are far too many orders of magnitude to span the gap. Do you now see why a passive scenario is completely absurd? The required RF field strengths would be so large as to cause spontaneous arcing among metal components.

As for your FM hypothesis, there are at least two significant problems that make the scenario worse, not better. First, a crystal detector does not demodulate FM particularly well (you can do it, by a process known as slope detection, but it degrades sensitivity even further). More seriously, FM broadcast radio did not exist in the UK at the time that the Pye radio was built.

In summary, the best hypotheses remain what I said earlier: There is a hoax going on, in which either the report is fabricated, or the radio actually has a source of power, or is not in fact wirelessly operated. Given the reputation of that publication, the hoax hypothesis looks like a strong contender.


ETA: If we are to infer from the article that the radio is otherwise unmodified, then it is important to recognize that unpowered tubes/valves do not convey signals very well. Whatever power is received by the antenna will have a tough time getting to the detector at all.

It's a hoax/joke/gag.
I didn't really mean to say that it couldn't be a hoax, I was suggesting a way this effect could be produced.

The problem is that unless we are proposing a conspiracy involving everyone or most of the people at the museum, it is either coincidence or a hoax perpetrated by one or a few. The reason for this is that the radio has been examined by multiple people, both on the outside and inside, including by the former RAF radio operator and a person described as the resident radio expert. Of course, we do not really know how thorough the examination was, but we should assume that, unless the two so called experts were in on the hoax, the most obvious things like an visible active radio reciever or some wires would have been discovered

Me suggesting FM was just to point out that the length of antenna is very dependent on frequency used, and also, any local radio would probably use a FM transmitter. That FM was not used at the time the radio was produced is rather irrelevant, as this type of reception would not be in the design, but a coincidence of it, or due to aging.

I was not suggesting that any of the valves had any active part in the reception, though they may have a passive impact, as resistances and capacitance and so on. I have been thinking a little, there is another way than electrolytic that detection could be achieved; A metal oxide junction could form, especially if there are some poor joint in there, and this might cause a diode effect, this would be similar to the improvised receivers people have rigged up in war time.

If it is a hoax, then of course, someone that do know a bit about radios might have rigged the set to receive signals they send, as I doubt someone checking inside would actually bother to look over the actual circuit. It is even conceivable to hide batteries inside, for example, one of those huge electrolyte capacitors they used back then. I know that sometimes restorers will replace the insides of such capacitors with modern capacitors, so someone with a bit of experience might be able to do this without it being very visible. Actually, it would probably be possible to hide an entire reciever inside those things. Of course, the radio is described as containing cobwebs and spiders, but it wouldn't be impossible to fake a dusty, neglected look, at least one that would pass a superficial examination...

Still, I feel that modifications are a complex solution, and that the simplest one may be that someone just noticed that the radio did pick up some signals by accident, and proceeded to use this to play a trick on people, I have started to believe it is a hoax to some extent though, the intermittent nature of the sound does not fit very well with the idea of some local radio station being picked up, nor does the old music/speech, but someone pulling a joke or perhaps trying to create some publicity for the museum might very well choose to use things that are seemingly related to the period the room is decorated in.