About setting up the Ural-84 transceiver. Scheme, description

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About setting up the Ural-84 transceiver. Encyclopedia of radio electronics and electrical engineering

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Encyclopedia of radio electronics and electrical engineering / Civil radio communications

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When setting up the Ural-84 transceiver, I could not achieve the required receiver sensitivity. It turned out that the cascode circuit, assembled from randomly selected transistors VT5, VT6 [1], had a gain of 6 ... 8 dB instead of 20 dB according to the description.

Using the recommendations described in [2], I selected transistors VT5, VT6 according to the initial drain current so that the initial drain current VT5 (KP303E) was several milliamps more than the initial drain current VT6 (KP312A). At the same time, it was possible to achieve the required amplification of the cascode circuit. If the initial drain current VT5 exceeded the initial drain current VT6 by more than 5 ... 6 mA, then the cascode circuit does not work well.

Literature

1. The best designs of the 31st and 32nd amateur radio exhibitions. Shortwave transceiver Ural-84. - M.: DOSAAF, 1989
2. V. Polyakov. Cascode and differential amplifiers on field-effect transistors. - Radio, No. 1/84.

Author: A. Senchurov (RB4EK), Krivoy Rog; Publication: N. Bolshakov, rf.atnn.ru

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