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The N.V. Dordtsche Radio-Industrie was
founded in 1928. The director was Mr. Wilhelm B. A.
Günther, technical designer was Martinus Hellingman,
born on December 9, 1889 in Purmerend, teacher
on a technical school in Dordrecht.
The company originated from a long-standing
company of Günther, which traded in optical articles and
medical instruments. The address was Groenmarkt
50 in Dordrecht.
The
factory made the 4-valve Dynaco A and the 5-valve Dynaco
B receivers, a number of amplifiers and a radiogram,
based on the Dynaco B radio. |
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The
company did not exist very long.
After 1929 no radios were made anymore. |
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Martinus Hellingman published the
book "Radio
telegrafie en
telefonie;
populair
wetenschappelijke
behandeling van de
theoretische
grondslagen,
waarop een
radio-zender en
-ontvanger
berust"
("Radio
telegraphy and telephony; popular scientific
description of the theoretical foundations on
which a radio transmitter and receiver is
based") in 1925.
He also wrote a book on physics,
was co-author of another book on physics and
gave courses and lectures on radio technology at
the Volksuniversiteit of Dordrecht.
He lived at Reeweg
110 in Dordrecht. |
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In the October 1927 issue
of Radio Nieuws magazine, he wrote an
article about the electro-dynamic loudspeaker he
applied a year later in the Dynaco radios. |
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In 1934 he made a
short-wave transmitter for the MTS technical
school where he worked.
The
station used the call sign PIIJ and transmitted
at 42.35 meters.
The transmitter focused among other
things on contacts with MTS students in the
Dutch East Indies.
The station was still active in 1950. Hellingman
died in Dordrecht on February 29, 1973. He was
82. |
