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Old 26th Mar 2021, 12:46 am   #1
peter_scott
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Default Marconi Wireless Station Clifden

I was looking at the location of this station that was in Galway between 1907 and 1922. In addition to the wireless station this location is also famous for being the landing site for Alcock and Brown in 1919.

There isn't much today to show where the wireless station was but maps show the huge condenser shed with wires radiating out from it eastwards. The photo below is looking towards the backside of the condenser shed with the masts and wires on the far side.

The landing site of the Vimy is marked with a bullet shaped monument and if the location is accurate then it was within the span of the aerial wires. There is no mention in the accounts that I've read of any collision with the aerial. I wonder if they flew in beneath it?

The Google "Aerial View" is compared with the Wireless Station map.

Peter
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Old 26th Mar 2021, 1:11 am   #2
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Default Re: Marconi Wireless Station Clifden

Interesting. Would dearly love to know the answer. I am currently reading a book on the Marconi Hall Street Works- what fascinating times they were.
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Old 26th Mar 2021, 9:37 am   #3
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Default Re: Marconi Wireless Station Clifden

Even the orientation of the aircraft at the landing site would be interesting to understand their approach direction.

Peter
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Old 26th Mar 2021, 1:57 pm   #4
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Default Re: Marconi Wireless Station Clifden

I have taken the Bing Aerial View and superimposed it on the Wireless Station Map.

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Old 27th Mar 2021, 8:54 am   #5
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Default Re: Marconi Wireless Station Clifden

There's no fool like an old fool!

Most people would think that I'm old enough now not to take everything at face value but to question everything.

My first mistake was with the Marconi Wireless Site map. The aerial system was not as wide as the map suggests because the outer rows of points described as masts were not masts at all. They were anchor points for guy wires supporting the inner rows of masts.

My second mistake was to accept the map location described as the landing site of Alcock and Brown's aircraft. It was probably a good vantage point from which to witness the landing and it was also a nice place to site a monument but that was as far as it goes.

Peter
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Old 31st Mar 2021, 11:18 am   #6
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Default Re: Marconi Wireless Station Clifden

The aerial system did start out with a mast beyond the position of the Alcock and Brown monument. As on the right hand side in the coloured sketch but the whole array was later reduced to a width bounded by the centre two rows of masts.

As for the monument, it started out with a sign on the top saying "Landing Site 500 metres" however, the sign did not survive the weather or the subsequent refurbishment. My red arrow starts approx. at the monument and ends about 500 metres distant in the general direction.

Peter
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Old 31st Mar 2021, 2:19 pm   #7
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Default Re: Marconi Wireless Station Clifden

I'd wondered about this myself- in the many articles about this epic and incident-prone flight, the wireless station usually only gets a passing mention. I wouldn't be surprised if this station, on the very eastern edge of the North Atlantic, didn't undergo considerable investment and updating during the course of WW1- perhaps the aerial system underwent revision then.

Scant and varying details describe the aircraft electrical system as consisting of the generator and a large battery providing power for instruments, heated flying suits, intercommunication and the radio apparatus. A well-known part of the story is the failure of the slip-stream powered generator a few hours into the flight, (some sources say that the airscrew broke away) leaving them unable to use the radio or talk to each other and resorting to hand signals amidst the horrendous racket of a broken exhaust. I wonder if the generator provided HT and battery LT- that would explain the failure of the "electronic" part of the set-up, or if they simply regarded instruments and suit-heating as having priority on battery power. Seeing the Marconi masts might have encouraged them to set down nearby and at least get word out quickly that the previous radio silence didn't have an ominous explanation.

Sorry for the thread diversion, but at least it's radio-orientated!
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Old 31st Mar 2021, 5:51 pm   #8
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Default Re: Marconi Wireless Station Clifden

Their initial plan had been to land at Galway. There were other competitors who set off about the same time hoping to win the Daily Mail £10k prize for the first non-stop crossing in a heavier than air machine. The generator in the Vimy had failed early into the flight so they spent most of the time frozen in their electrically heated suits. Their radio had no power and they had no idea whether a competitor was close behind and might land before them and win the prize so landing asap was more attractive than pressing on to their planned destination. It certainly must have been a real trial.

Peter
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Old 1st Apr 2021, 11:20 am   #9
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Default Re: Marconi Wireless Station Clifden

Landing a large bomber somewhere there isn't actually a runway and surviving is pretty good going. Without a functional radio on the Vimy, the folk at the radio station would have had no prior warning, just the sound of approaching engines. I must confess to a very strong preference for runways for landings. We take radio a bit too much for granted, but there are still procedures for how to approach an airport without radio so that other traffic can be cleared out of your way.

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Old 1st Apr 2021, 12:55 pm   #10
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Default Re: Marconi Wireless Station Clifden

In this case, what other traffic?
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Old 1st Apr 2021, 2:04 pm   #11
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Default Re: Marconi Wireless Station Clifden

I was commenting that radio-less approach procedures are still in place... and therefore we DO now have other traffic with which they must work.

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Old 1st Apr 2021, 7:27 pm   #12
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Default Re: Marconi Wireless Station Clifden

I don't how widespread the knowledge was but it was known locally that the flight was taking place and that it was expected to land at Galway.

Watch this video from 5.26

Peter
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Old 2nd Apr 2021, 12:29 am   #13
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Default Re: Marconi Wireless Station Clifden

Thanks for that most interesting video, featuring people who actually witnessed the landing. The accounts I have read often mention that they crash-landed in a peat bog, but the Marconi guy who witnessed it said that they did in fact land safely and only came to grief when taxiing. Interesting comment by the old lady that the site for the Marconi station was chosen due to its proximity to the peat bog. As well as providing fuel, its wetness would no doubt have provided a better earth than the thin soil/bare rock that predominates in that part of Ireland.
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Old 3rd Apr 2021, 9:30 am   #14
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Default Re: Marconi Wireless Station Clifden

The radio station was really a very different world. The Condenser House was 350 ft long containing an air spaced condenser comprising 1800 galvanised steel plates 30' x 12' spread on either side of the transmitter and receiver in the centre section. Initially the connections to the aerial system were on the opposite side from the masts but later the aerial was redesigned and fed from the same side as the masts.

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Old 3rd Apr 2021, 2:39 pm   #15
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Default Re: Marconi Wireless Station Clifden

The transmitter used spark techniques to pulse a resonant circuit coupled to the aerial. Power came from a high voltage DC generator (or a high voltage battery) that alternately charged two capacitors in series where each has a spark gap that connects through the resonant circuit. A form of electro-mechanical multivibrator. The generator or battery voltage was about 12kV so I would not have wanted to go anywhere near the plates in the Condenser House. The capacitors alternately discharge pulsing the resonant circuit. This generated a fairly continuous wave instead of the rather random pulsing of a simple buzzer type of spark generator and therefor didn't fill the entire RF spectrum with as much noise. That said, in order for the operator at the receiving end hear a tone rather than a simple on/off click a further refinement was added such that the timing of the spark discharges were forced to occur with a regular frequency. The carrier generally used was 45kHz and the tone imposed on the sparking around 8kHz. You can see Marconi's description in the Nobel Lecture he gave. The transmitter is shown in Figure 24.

I think the simple spark spectrum would have been like the first screen shot and the toned one more like the second screen shot.

At the receiving end the detector used was the famous Marconi Magnetic Detector that passed a continuous loop of soft iron wire through two concentric coils. One coil was connected to the tuner or aerial arrangement and the other to a headphone. The wire loop was driven round by clockwork and as it entered the coils it was magnetised by a horse shoe maget but the received signal in the tuner/aerial coil acted to degauss the magnetism depending on the amplitude of the received signal. A second magnet was also arranged at the point where the wire exited the coils. I have no idea what it did.

Peter
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Old 3rd Apr 2021, 5:19 pm   #16
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Default Re: Marconi Wireless Station Clifden

Amazing stuff- reading about 12kV circuits ivolving 1800 huge steel plates sitting on a peat bog on the west coast of Ireland, I can smell the ozone just looking at the pictures!
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Old 3rd Apr 2021, 6:29 pm   #17
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Default Re: Marconi Wireless Station Clifden

I do like Peter's combined spectrum and selfie photos.

1800 huge steel plates at 12kV is scary, and the ozone from the whirling spark gaps must have added to the bracing reputation of the sea air.

Isn't it amazing what it took in the early days, yet an FT101 and a G5RV can accomplish it relatively easily. Valves, transistors and the understanding of suitable frequencies have brought us a long way.

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Old 4th Apr 2021, 12:40 am   #18
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Default Re: Marconi Wireless Station Clifden

That receiver looks like a wire recorder with one magnet erasing and the other providing bias. The RF would record pulses on the wire.
I am assuming that there is another coil reading the wire and feeding the head phones.
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Old 4th Apr 2021, 8:21 am   #19
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Default Re: Marconi Wireless Station Clifden

Yes, there are two coils mounted coaxially, the inner and longer one connecting between aerial and earth and the outer one connecting to a headphone. The headphone will not respond to the RF and nor would it sense the envelope shape of the RF because any magnetic flux changes would be cancelled/degaussed by the RF but given the magnetic bias to the moving wire from the horse shoe magnet at the entry to the coils the RF degaussing now leaves a flux that changes in proportion to the RF amplitude. Glasslinger gives a nice demonstration.

Peter
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Old 4th Apr 2021, 9:11 am   #20
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Default Re: Marconi Wireless Station Clifden

To someone like me who knows very little about aerials the system used at Clifden was also interesting. It consisted of a set of masts 200ft tall that supported aerial wires running horizontally away from the direction of the receiving station across the Atlantic at Glace Bay. Apparently most of the transmitted radiation came from the vertical parts rather than the long horizontals. If you have a simple vertical aerial then towards the top the current tends to zero but the horizontal additions add capacitance to the aerial and increase the current flow at the top and add to the effective length or height although also increasing the optimal wavelength.

Peter
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