Page 30 - EngineerIT December 2021

AMATEUR RADIO

Centenary of the first transatlantic

radio communication

2 December 2021 marks the Another driving force in Britain
centenary of the first transatlantic The driving force for these tests in Britain was Philip Coursey, 2JK, an experienced engineer
1amateur radio communication with the Dubilier Condenser Co who had been an assistant to Ambrose Fleming (of diode
between the US and the UK. It also marks valve fame) and became honorary secretary of the Radio Society of Great Britain (RSGB) in
the birth of shortwave communication. 1924. Coursey publicised the tests through the Wireless Society of London, the forerunner of
Early long-distance services used surface the RSGB, and after several radio manufacturers offered handsome prizes, over 250 British
wave propagation at very low frequencies, amateurs declared they would take part.
which are attenuated along the path. Longer The ARRL organised the US transmissions, which took place on 2, 4 and 6 February 1921
distances and higher frequencies using this during the early hours of the morning in Britain, when most of the Atlantic path was in
method meant more signal attenuation. darkness. Early receivers had limited selectivity and Coursey appealed to all British amateurs
This and the difficulties of generating to observe radio silence during the tests. To avoid any false claims of reception, the US stations
and detecting higher frequencies, made transmitted secret code words in addition to their call signs and on one night they also sent
discovery of shortwave propagation difficult pre-assigned portions of a text. To the disappointment of all participants, the tests were a
for commercial services. complete failure as not one British listener received a signal that could unquestionably be
Between 1921 and 1924, radio attributed to an American amateur.
amateurs experimented with transmitting With hindsight, since short wave radio conditions can be variable, it was an error to limit
across the Atlantic. Sponsored by ARRL, the tests to only three short sessions. Although no-one qualified for the reception prizes, W
these transatlantic tests aimed to prove R Wade of Bristol was awarded a three-valve Burnham audio amplifier for the description of
that shorter wavelength frequencies could the receiver he used, which was a home-built design with seven valves, including a separate
propagate long distances using transmitters heterodyne oscillator. Apart from the short duration of the tests, the entrants also complained
running less than 1 kW. Radio amateurs that they had to contend with severe interference from the harmonics of high power European
conducted the first successful transatlantic commercial stations (such as Nantes) operating on longer wavelengths, as well as radiation
tests in December 1921, operating in the from the self-heterodyne receivers of other participants. This was a problem that was later to
200 metre mediumwave band (1500 kHz) plague the fledgling broadcasting industry for many years.
- the shortest wavelength then available to There was great enthusiasm on both sides of the Atlantic for further tests the following
amateurs. winter and these were scheduled on the nights of 8 to 17 December 1921. This time round
Although operation on wavelengths the sessions were extended to six hours per night, with the first two and a half hours being a
shorter than 200 metres was technically
illegal (but tolerated as the authorities
mistakenly believed at first that such
frequencies were useless for commercial
or military use), amateurs began to
experiment with those wavelengths using
newly available vacuum tubes shortly after
World War I.

First amateur radio attempt to cross
the Atlantic
In 1921, the editor of Everyday Engineering,
M B Sleeper, promoted the first trans-
atlantic test to the amateur world to take
place in February 1921. It did not happen
as the publication was suspended. Sleeper
approached the American Radio Relay
League to take over his initiative and to
proceed with the test. Transatlantic Tests Succeed January 1922 Cover QST Issue December 1921

EngineerIT | December 2021 | 28