The Koliber 2 is one of the three versions of the Koliber travel radio produced between 1962 and 1966 by the Zakłady Wyrobów Elektrotechnicznych Eltra in Bydgoszcz. The Kolibers are a development of the Eltra MOT-59 – the first portable radio manufactured in Bydgoszcz. The solutions adopted also became the basis for other travel radios such as the Sylwia, Minor, Kama and Dominika.
The Koliber 2 is a superheterodyne, improved from the original version through the use of seven transistors and a germanium diode on a printed circuit board. The first semiconductor diode was developed by Russell Ohl in 1939. The “barrier” in the form of a fissure that separates areas with positive and negative charges enables the flow of current only in one direction. The prototype transistor was designed a decade later and was developed by a team comprising John Bardeen, William Shockley, and Walter Brattain (who were jointly awarded the Nobel Prize in physics for it in 1956). It enabled the outdated electron-array vacuum tubes to be replaced in the electrical circuits of radio and television equipment. This was important as the tubes were characterised not only by high power consumption, but also high heat emission.
In contrast to the tubes, the transistor has a lower power consumption, does not emit heat, and has smaller dimensions, thus enabling devices to be miniaturised.
The monophonic Koliber 2 was equipped with five tuned circuits, which allowed reception of medium and long wave bands. Thanks to its small dimensions it fulfilled the role of a portable, battery-powered radio (with the possibility of connecting it to the mains, but only using a special converter). The Koliber 2 has a built-in ferrite antenna and a Tonsil GD 7/0,2 magnetic electric speaker.
The device is enclosed in a cuboid housing of grey plastic with rounded edges and corners. The surface of the front wall is divided with vertical bands placed at regular, narrow intervals, in the form of isosceles triangles with trimmed top corners. On the right side of the front is a transparent tuning knob with digits of different sizes in an art déco-style typeface. On the left is a speaker covered with a light-coloured fabric that is visible through the square hole with the vertical bands described above. Below it is a light-coloured inscription with the name of the radio. On the sides, there are two metal belt clips, and on the top wall there is a volume knob with a power switch and a radio band switch.

Author: Filip Wróblewski