03-04-2021, 06:24 PM
(This post was last modified: 03-04-2021, 06:29 PM by peter scott.)
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
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.
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 magnet 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
Watch this video from 5.26
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.
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 magnet 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
