Half Kw Phone Concert SetSPECIFICATIONS
Model: For some reason, Canadian Marconi did not assign model numbers to their equipment in the early years so the title of this web page becomes the model number.
Modes: CW, ICW, AM (ICW was also referred to as "Tonic Train" in those early years).
Transmitter frequency Range:?
Receiver frequency range: 300 to 3,000 metres (1000 to 100 kHz respectively)
Power output: 500 watts
Range: 100 miles by day. Further at night.
Transmitter Tubes: Three in total. Oscillation tube is MT-4; Control tube is MT-4; rectifier tube is MR-4 .
Filament voltage for transmitting tubes: 12 volts derived from a battery
Transmtting tube anode voltage: 1,000 to 2,000 volts
Receiver tubes: One in the receiving tuner'; 7 in the M-55 amplifier.
Mains power: A rotary converter provides a mains voltage of 85 VAC at150 cycles.
In 1913 , the Canadian government passed a law governing wireless transmitters. In that year, they gave Marconi Wireless Telegraph Company (MTWC) an experimental licence with the call sign XWA. The X meant experimental. There were no licences before that and Toronto radio amateurs gave themselves call signs beginning with X a year before. One of them had been using XWA. He was not allowed to keep it. Broadcast licences were issued on April 1 1922. MWTC was given the call sign CFCF for broadcasting and 9AM for experimental work.
Prior to that, MTWC was competing for another radio "first" .The Americans claimed that KDKA in Pittsburgh was the first radio station in North America. A legitimate counterclaim was made by Marconi's station XWA in Montreal. Both stations were experimenting with broadcasts to 1ocal "hams in 1919. No record appears to have been kept as to the first time a transmission was received from either of these stations by an audience, ThIngs didn't happen that way.
However, if a scheduled broadcast is accepted as a starting point, Canada's XWA beat out the American KDKA. The first scheduled broadcast in Nothh America was a musical program relayed on May 20,1920 from XWA in Montreal to a meeting of The Royal Society of Canada in Ottawa. The first scheduled broadcast from KDKA in Pittsburgh was a broadcast of the HardingCox presidential election returns on November 2, 1920, Meanwhile, other countries such as Holland and England were also commencing broadcasts.
This article in the June 1, 1920 edition of the Electrical News periodical .provides some addition details about the broadcast to the Royal Society of Canada.
parts of the Phone Concert transmitter. Click on thumbnail to enlarge,
(image courtesy Canada Wireless Magazine)
Item K is the Marconi
(UK) type 70 tuner.
|Simplified diagram of the CW transmitter circuit. Click on thumbnail to enlarge. (image courtesy Canada Wireless Magazine)|
|The MR4 was the rectifier valve used in the Phone Concert set. (Image courtesy Wireless Word Radio Review January 1923)|
|The Phone Cabinet
set in action. Broadcast station XWA, was owned and operated by the Canadian
Marconi Company from their factory on William Street in Montreal. This
it how it looked in Sept 1920. This 500 watt set was imported from
the MWT factory in Chelmsford England by Marconi Canada and installed
in experimental station XWA iwhere It would broadcast on 1200 metres
(250 KHz) .
The transmitter in this photo does not quite resemble the one in the photo above. It is presumed that the previous photo is an earlier variant . Download image to enlarge. (Image via Radio News of Canada, March 1929)
Contributors and Credits:
1) Lewis Bodkin <5bodkin555(at)gmail.com>
2) Handbook of Technical Instruction for Wireless Telegraphists (HTI)
3) Handbook, and Canadian Wireless , Aug. 1921, and May 1922.
4) Radio News of Canada
5) The Early Development of Radio in Canada 1901 to 1930 by Robert Murray ; page 24
Apr 20 19