Nagra II (2) Autonome Tape Recorder

• Brand: Nagra

The Nagra II is a self-contained tape recorder using 1/4 " magnetic tape in reels of 5", powered by two batteries of 2 x 1.5 V for the tube filaments and one of 135 V.

During the year of 1952 Stefan Kudelski developed the Nagra I equipped with clockwork motor (Thorens) and low power electronic tubes. Kudelski sold some unities of the Nagra I for Radio broadcast stations and reporters with highly acclaimed success. In 1953, in a new facility, Nagra began the production of the Nagra II (a Nagra I with the option to have an external modulometer [a kind of a VU meter] in the sidewall. Later the Nagra II was improved to the Nagra II b and, after this, in 1955, to the Nagra II c (a Nagra II with some improvements in electronics  and using the first Nagra printed circuit).

In Nagra I and Nagra II tape transport is done using a mechanical spring (steel tape) motor (Thorens 144\F).  Electronics is hand wired within a very compact volume of 110 mm x 110 mm x 90 mm where the four tubes (pentodes), two DAF96 and two DL94, are assembled.

The spring motor provides about  6 minutes of continuous recording and the battery discharge in about 5 hours of continuous use of electronics. The recorder have a mechanical indicator of available tape (or recording time) that is based on the number of revolutions available of spring tape of the motor. 

With the help of the hand crank, the spring strenght may be recharged. Rewind of tape is done manually by using a small key that can be plugged in a hole in the back of recorder.

The three parts metallic box measures 300 mm x 152 mm x 123 mm but the external dimensions of the recorder (because of buttons and the crank dimension)  occupies 330 mm x 175 mm x 123 mm.

In questo link sono elencati 48 modelli, di cui 45 con immagini e 19 con schemi.
Elenco delle radio e altri apparecchi della Kudelski SA; Cheseaux-sur-Lausanne