UPG (Peregovornoe ustr) 1980
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The negotiating device loud-speaking "UPG" since 1980 produced an experimental plant NPO "Wave". The device is intended for two-way loud-speaking wired communication between two subscribers at a distance of up to 1000 meters. Nominal output power 125 mW. The operating frequency range is 450 ... 3000 Hz. Dimensions of one device 125x75x56 mm. Weight 450 grams.
Documentation:
Based on information from collection of Valery Khartchenko