Radio in 1909

Radio Record, Volume III, Issue 29, 31 January 1930, Page 37

Radio in 1909

Then in Infancy T is nearly thirty years since a small band of enthusiasts made a transportable receiver, writes a correspondent to "World Radio." It was wheeled round the streets on a barrow _--there were no motor-cars to help, It was like this. Marquis (then Senatore) Marconi had a mysterious house with a pole on the West Cliff at Bournemouth and was trying to call the Isle-of Wight. If a big man like that could communicate for miles, why should we not try a few yards? So we started. First efforts-to get a throw of a galvo when a Rumkorff coil sparked; we had not much material and no great possessions. The experiment worked across a table-good luck. Hmboldened we constructed a Branly coherer; spent hours filing steel, nickel and silver; sifting the filings and mixing them in various proportions. ‘Then brass rods had to be cut and filed to fit a glass tubepatience. Patience and bad words when sealing the glass! But the coherer worked, and this made us arrange our transportable as we were getting beyond our neighhoux’s gardens. Componentst A bar-

row, bamboo rods, some yards of aerial ‘and earth wire and a spike to stick in the earth; two receivers. Receiver No. 1-A tapping coherer of the ‘Branly type, and No. 2, a Popoff auto-. mati¢e carbon coherer, The first worked like this. Morse signals worked at home by a six-inch spark coil, the sparks fattened by Leyden jars and bed-post brass knobs, were received on our improvised aerial; the oscillations passed to earth through the tube of filings which partially stuck together and conducted a current better. Across the coherer was a relay circuit, as delicate as our crude methods would allow. A few milliamps. worked the oracle. The relay operated an electric bell and the back stroke of the hammer whacked .the tube and decohered the filingsshook them up. This was a poor arrangement for. the spark at the bell contact itself. cohered the filings and a mechanical spring tapper had to be arranged. The relay did heaps of things besides ringing a bell-exploded gunpowder, started a motor or anything else that could be started by an electric current. And many a practical. joke did we play "at a distance" with this receiver. The other receiver was a Popoff carbon and steel arrangement and this required no tapping, but would do no tricks except receive Morse signals. It was connected just as the more recent crystal and carried a small current from a couple of dry cells. Buzzing signals were heard in ’phones

placed across it. We had no variable condensers or tuning coils. Even in high places in those days, tuning consisted.of tapping a coil of wire on 2 ‘wood frame. So we trundled along, erecting the pole in some dark or deserted corner ; we were not escaping a Post Office license, but avoided as,far as possible the‘ interference‘ of youngsters. ‘ We progressed a little farther from home each trip and reached about a mile with our portable, and became of such importance that we were allowed to visit and photograph an early Marconi station-and spoke in Morse twenty miles across the ocean! . The Jone operator was. glad to receive visitors, but equally glad to come and have refreshment at the nearest country "house? Messages were scarce. When asked about lightning-"atmospherics" were not invented then-he said that when the sparks on the aerial reached more than an inch long he just cleared out. We took all. this information in-in those days. Hanging an aerial out of the window and listening to faint Morse was a slow job in 1900. ,