The Model 5100 was one of the most technically advanced radio receivers in communist Poland. The receiver with a built-in amplifier allowed reproduction of pseudo-quadrophonic sound (quasi-quadro). The quadrophony effect involved using the difference in the signal strength between the left and right channels, which gave an illusion of spatial sound. The Radmor 5100 was developed at Zakłady Radiowe Radmor in cooperation with the A/V section of the Industrial Telecommunications Institute (Przemysłowy Instytut Telekomunikacji – PIT) and with the Industrial Design Centre of PTH Unitech (OWP PTH Unitech). Prototypes of the 5100 model were built in 1976, and mass production began a year later, which was continued until 1979. The Radmor 5100 was sold in Poland and exported to France.
The Model 5100 is the first in a series of luxury class hi-fi radio receivers manufactured by Radmor. It employs a modular design typical for radio telephones for which the Zakłady Radiowe Radmor were famous. The electronic system of the receiver and its technical design was developed by Grzegorz Strzelewicz, the author of many designs of popular electronic devices (including Amator, Julia and Maria radios, as well as the Hi-Fi Mini, Slim-Line audio sets and the MD 3401 SD studio tape recorder). The external housing of the Radmor 5100 is a cuboid, one-part, chipboard veneered box, with a cross-section in the shape of a horizontal letter U. The receiver was built on an aluminium, anodised, spatial chassis on which structural components were installed, including the electrical system and the front housing panel with controls. On the one hand, such a solution enabled a streamlined production process, and on the other it facilitated repair work resulting from faults of electronic components. The disadvantages were the increased production cost and the necessity to lead wiring harnesses throughout the device. The front plate was made of brushed aluminium in two colour versions: black and silver. Due to the technology used, the black panels were sensitive to sunlight, which caused fading and discolouration to a copper or yellowish colour. Therefore, black versions of the receiver are rare.
The device was controlled using split knobs for source selection and radio reception mode. The receiver has a sensor programmer unit for eight radio stations and five rectangular VU meters. For the user’s convenience, the indicators are backlit in green. The 5100 receiver is designed (both in terms of external and technical design) to work with the Radmor 5171 graphical corrector and the Radmor 5122 AM tuner.

Authors: Piotr Turowski, Filip Wróblewski