Tesla 4002A

Tuned-radio-frequency TV receiver with a round picture tube with 25 cm diameter, the diagonal of the visible image was even smaller because the bakelite frame did not stretch out to the full diameter of the tube. This device is based on the 4001A receiver, but is equipped with a radio receiver based on the Talisman. The tuned-radio-frequency principle of the TV receiver did not enable any channel change, the receiver was tuned to a single channel, on which the Prague and Ostrava transmitter operated. The components of the TV receiver are used from military radar production. It was possible to switch off the video part and receive only the TV sound - in the beginnings, Czechoslovak TV operated only in the evenings and a test pattern was broadcast during the day, accompanied with the sound of the Czechoslovak Radio. The picture was very small, but as this TV receiver was the only one manufactured in Czechoslovakia, it was commonly bought to be used in pubs, municipal authorities etc. and was watched by many people together. It was possible to enlarge the picture with a plastic magnifying lens placed in front of the screen. The lens was hollow and would be filled with water. However, the viewing angle would be reduced by this. The receivers have been commonly modified to use a 35 cm square picture tube or rebuilt as a superheterodyne with channel switching. It was also possible to buy a color plastic foil that had a blue stripe on the top, orange in the middle and green at the bottom. It would be sticked on the screen and would make a "color" picture.