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kathrein: MRK31 s/n 1603

Martin Renz Ernst Erb Vincent de Franco Martin Bösch Mark Hippenstiel Bernhard Nagel Otmar Jung Heribert Jung Eilert Menke 
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Forum » Radios and other type of sets (Physics) etc. » MODELS DISPLAYED » kathrein: MRK31 s/n 1603
Georges Van Campenhout
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19.May.20 12:16
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Dear Forum members,

my set, s/n 1603 does not have the digital frequency meter (MZE01). Perhaps this is a cheaper version?


Unfortunately, I cannot identify the Blaupunkt car radio that has been used. There is no label present with type- and serial number.

This is certainly not a standard radio: at the rear there is a gold plated RF connector, probably to connect it to the frequency meter, and furthermore 3 additional cables (blue, grey and green).

At the left side (see second picture) there is a black shielded cable, connected to the pcb at the rear of the 100 µA meter.

The radio itself is defective...

Best regards




This article was edited 19.May.20 12:18 by Georges Van Campenhout .

Heiner Herrmann
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21.May.20 03:09
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Kathrein model is listed here, please look at the description. The inbuilt radio is a blaupunkt, frankfurt stereo asu, this radio and various brandings of it, is also listed here. Just search "frankfurt stereo asu". The modifications are made by kathrein, feeding out the avr-voltage and amplification of that voltage by a logarithmic amp. The oscillator signal is fed towards the counter module.

The 3 extra wires are for: stereo lamp, switching of AFC and ASU( impulse interference rejection).

The proper front scale photo you will find at site "frankfurt stereo asu" here in on right hand side, additional photos. "Blaupunkt" left, bottom corner, "Stereo" right-hand bottom corner. ASU on top of radio housing, signal-red paper print "ASU".


This article was edited 21.May.20 03:16 by Heiner Herrmann .