Jan 11, 2014

ChennaiHamsBlogspot visitor stats : Exciting story so far

Very happy to share below visitor statistics till date from startup in 2009 of ChennaiHamsBlogspot which is really encouraging for us to continue to put efforts to improve this free forum further so that this wonderful hobby keeps growing to greater heights . Total visitor count has crossed 1 lac+ visitors and continues to grow day by day and more exciting is that fact that amatuer radio lovers from around 169 countries across the world have visited the blog so far and enjoyed the knowledge/info shared . From a humble beginning in 2009 , we thank everyone who visited and continued to visit the blog

The famous World War II Marconi R1155 Communications Receiver!!!!

The Marconi R1155 is a World War II era receiver produced for the British Royal Air Force. It was used in Lancaster and Halifax bombers and includes special circuitry for direction finding.

The R1155 tunes longwave down to 75KHz and shortwave up to 18MHz, with a couple of gaps along the way. Fortunately the broadcast band is covered from 600KHz to 1500KHz, so there is still something to tune in today. Aside from the DF circuitry it's a fairly standard multi-band super-het with one RF stage, mixer-oscillator, two IF stages, detector, one audio stage, and a magic-eye tuning indicator.

An audio power output stage was not included as the receiver was only used with headphones originally. There is no internal power supply as B+ and filament power were supplied from an external source when installed in an aircraft. The unit below the receiver in the photo is a home-made power supply and audio amplifier, described further below.

Many of these receivers were sold as surplus after the war. In Canada they were sold by the War Assets Corporation (see advertisement: XTAL, Jan 1947). They were commonly purchased by hams. Many of them were then extensively modified, typically by removing the DF circuitry and/or installing a power supply or audio amplifier inside. 

Jan 4, 2014

Titanic's Marconi Wireless Room (set) video Tour

This is the main set for our upcoming film "The Last Signals". The film is an entirely factual depiction of the sinking from Harold Bride's point of view and the film will play out exactly how the real disaster did.

This set took many months of research and labor to make, and nearly $2,000. It will be flooded and destroyed on camera

Jan 3, 2014

The Titanic radio department - a brief background!!!!

The Titanic radio department in 1912- a brief background

The Titanic's "wireless" equipment was the most powerful in use at the time in 1912 . The main transmitter was a rotary spark design, powered by a 5 kW motor alternator, fed from the ship's lighting circuit.
The equipment operated into a 4 wire antenna suspended between the ship's 2 masts, some 250 feet above the sea.  There was also a battery powered emergency transmitter.
The main transmitter was housed in a special room, known as the "Silent Room". This room was located next door to the operating room, and specially insulated to reduce interference to the main receiver.
The equipment's guaranteed working range was 250 miles, but communications could be maintained for up to 400 miles during daylight and up to 2000 miles at night.

In charge was 25 year old John (Jack) G. Phillips (left), with 21 year old Harold Bride (right) as the deputy or second R/O. The R/O's remained at their posts until about 3 minutes before the vessel foundered... even after being released from their duties by the Captain.
Harold Bride remarked that water could be heard flooding into the wheelhouse as he and Jack Phillips abandoned the radio room. Jack Phillips was still sending as the power supply to the radio room failed...
The Titanic Radio Officers did great honour to their profession.
Jack Phillips died of hypothermia on or near Collapsible lifeboat B - his body was never recovered......
Harold Bride left the sea after WW1, and faded into obscurity. He died in Scotland in 1956.

The left hand photo actually shows the Marconi wireless Room of the Titanic's sister ship Olympic, with Radio Officer Brent receiving a message.
In the right hand picture Phillips and another R/O (NOT Harold Bride) are shown on the White Star vessel "Adriatic" (both photos from the Father Browne collection).

Olympic's Marconi Room - taken on her maiden voyage.  Note the external porthole in the centre of picture.  
Titanic's Marconi Room was located inboard (more detail later).

The Titanic Marconi room set from the James Cameron movie.
This set quite accurately portrays Titanic's sister ship Olympic's Marconi Room.
The Titanic set was based on archival pictures of Olympic, with the window omitted (see the Olympic photo below). 

Another view of the Titanic radio room set from the James Cameron movie.
Clearly, no expense has been spared...note the Marconi uniform cap on the operating desk.

A Marconi wireless telegram from the RMS Olympic, Titanic’s sister ship, reports the Carpathia’s rush to the site where the Titanic went down. "Found boats and wreckage only," it says in part. "About 675 souls saved crew and passengers.
A Marconi wireless telegram from the RMS Olympic, Titanic’s sister ship, reports the Carpathia’s rush to the site where the Titanic went down. 

"Found boats and wreckage only," it says in part. "About 675 souls saved crew and passengers.

NOSTALGIC MEMORIES : On 12 December 1901 radio crossed for the firsttime across the Atlantic THE ATLANTIC

On 12 December 1901, Guglielmo Marconi received a radio signal that had been sent by his colleagues across the Atlantic. Although wireless telegraphy was not new - it had started to be used commercially by coastal shipping three years previously - Marconi's demonstration was exceptional.
To begin with, there was no reason to suppose that a radio signal would follow the curvature of the earth. As an eminent scientist said at the time, "there is a mountain of water one hundred miles high to be got over, and electric waves tend to go straight".
Despite this, Marconi - at 27 years of age - persuaded the hard-headed directors of his newly formed Wireless Telegraph Company to invest �50,000 and a lot of time in the experiment. This was a considerable investment - equal to several millions of pounds today - by a small company still existing on its capital.
Marconi's confidence was based on his experience of radio transmissions around England1, to France and to an experimental station in the south west of Ireland. For the Atlantic attempt, he set up a new station at Poldhu in Cornwall. His aerial comprised twenty-four ships' masts each 200 feet high, and the transmitter was powered by a 32 brake horsepower engine driving a 25 kilowatt alternator whose 2,000 volts were then boosted to 20,000 volts. At the receiving end, in St John's Newfoundland, Marconi waited with kites and balloons to hold an aerial wire aloft. In the event, a kite with 500 feet of wire received the first signals - the three dots of the Morse code letter S   
Public reaction was mixed. The Daily Telegraph reported, "The view generally held is that "electric strays" were responsible for activating the delicate instrument" while The Times and the technical press - despite accepting that the message had been sent - were doubtful that transatlantic wireless communication had any practical application.
Better news, however, came in an unlikely form. The Anglo-American Telegraph Company immediately wrote to Marconi saying that it had a monopoly on communications in Canada's Newfoundland and Marconi was to stop transmissions immediately. This he did, and was immediately courted by Canadian and United States authorities incensed by the company's attitude, and keen to be involved in a technology that they recognised as having great potential.
The Government of Canada offered a free site and $80,000 dollars towards the cost of building and equipping a wireless station at Cape Breton - provided Marconi agreed a maximum of 10 cents a word for sending commercial messages: the cablegram rate was 25 cents a word.
Despite only three days' notice, a dinner in Marconi's honour given by the American Institute of Electrical Engineers at the Waldorf-Astoria in New York attracted 300 delegates. The event - a month after the first signal - was a brilliant success. "At the two ends of the room," wrote historian Gordon Bussey2, "were large tablets, one reading "Poldhu" in white lamps and the other "St John's" in letters about a foot long. Immediately opposite the speaker's table was a similar tablet bearing the name "Marconi". Between the signs were strung, at frequent intervals, clusters of three lamps to represent the three dots, or "S", sent across the Atlantic from the Cornish coast to Newfoundland. At fitting times these were flashed or allowed to stay illuminated."
Progress in those early days was rapid. When Marconi returned to New York from Southampton in late February on the SS Philadelphia, he maintained readable messages with Poldhu up to 700 miles out by day, and 1,500 at night. The letter "S" was received 2,100 miles out, despite the limited aerial rigged on board.
In January 1903 the first wireless message was received in England directly from the United States. It read: "President of the United States to the King of England. In taking advantage of the wonderful triumph of scientific research and ingenuity which has been achieved in perfecting the system of wireless telegraphy, I extend on behalf of the American people my most cordial greetings and good wishes to you and the people of the British Empire. Theodore Roosevelt."
Although there were theories explaining why radio signals did not ignore the curve of the earth and disappear into space, it was not until 1924 that the existence of the ionosphere was discovered - bouncing them back to the ground. By then, transatlantic wireless communication was commonplace, and the first signal to be sent successfully around the globe - a possibility predicted by Marconi - was demonstrated two years later.
Marconi was born in 1874 in Bologna, Italy, studying Heinrich Hertz's theory of radio there and demonstrating its practice in experiments around the family home. He moved to Britain and filed his first patent in 1896, forming a company in 1897 which became Marconi's Wireless Telegraph Company (eventually Marconi plc) three years later.
The first advertised broadcast in Britain - using a Marconi transmitter - was made in 1920, and the first microwave telephone link was established by Marconi in 1932 between the Vatican and the Pope's summer residence. At that time Marconi was also demonstrating the potential of blind navigation, the forerunner of radar.
Marconi returned to Italy in 1935, and died there in 1937. In a tribute, wireless stations throughout the world observed two minutes silence and the radio spectrum was as silent as it had been forty years before.

The 700 people saved from the Titanic were "saved through one man, Mr. Marconi"

Jan 2, 2014

Another feather in Chennai's HAM cap : 4th VHF repeater (Vandu Net Repeater) Installed

We are happy to inform that one more repeater has been installed in Chennai.

Name of the Repeater: Vandu Net Repeater
Call Sign : VU2 LHS
Frequency : 145.550 MHz (Negative Shift)
Active from: 03-JAN-2014 for all HAMS

The Maha Meet Net Contest which was running at 144.900 MHz simplex is being shifted to Vandu Net Repeater from 03-JAN-2014. The timing is 21:15 to 21:45 hours. Please note the above change and continue to extend your active participation and cooperation.
Anna (VU2KBX)

Here comes the ever exciting MAHA Eyeball meet 2014!!!!!