To meet the needs of the many hams who have asked for a sensitive, first-rate bandswitching receiver in the lower price bracket, complete with speaker and power supply in one cabinet, the National Company has developed the brand new NC-57. Although moderate in price, this little receiver incorporates features usually found in more expensive models. Excellent tone quality, sensitivity, selectivity and high signal-to-noise ratio afford a level of performance which will appreciated by any operator. A superb receiver for the beginner, the NC-57 will be found ideal as a standby in any amateur station.


  • Continuous frequency coverage from 550 kc to 55 mc. Bandspread tuning at any frequency.

  • Seven tube superheterodyne (plus rectifier and voltage regulator).

  • Automatic noise limiter.

  • Built-in loudspeaker and A.C. power supply.

  • R.F. stage with panel controlled antenna trimmer.

  • Band switching made easy by means of simple 5 position switch.

  • Pitch control to adjust beat note on CW (code) signals.

  • Operates from 105-130 volts, 50-60 cycles A.C. (Provision for battery operation.)

  • Housed in a streamlined gray cabinet.

    R.F. Amplifier 6SG7
    Converter 6SB7-Y
    First I.F. Amplifier 6SG7
    Second I.F. Amplifier 6SG7
    Second Det. - A.V.C. - A.N.L. 6H6
    First Audio - C.W.O. 6SL7GT
    Audio Output 6V6GT/G
    Voltage Regulator OD3/VR-150
    Rectifier 5Y3GT/G

    TUNING SYSTEM: The three-gang main tuning capacitor, the panel-mounted Trimmer control and five sets of coils are used to tune the frequency range of the Receiver in five tuning bands as shown on the following table. The main tuning capacitor and bandspread capacitor are connected in parallel on all bands.

    A 35.0 - 54.0 Mc.
    B 12.0 - 35.0 Mc.
    C 4.4 - 12.0 Mc.
    D 1.55 - 4.4 Mc.
    E 0.56 - 1.55 Mc.

    The Amateur bands tuneable by the NC-57 are spread on the bandpread dial by means of the bandspread capacitor approximately as follows:

    A 6 50.0 - 54.0 Mc. 60
    B 10, 11 27.16 - 29.7 Mc. 62
    15 21.0 - 21.5 Mc. 37
    20 14.0 - 14.4 Mc. 75
    C 40 7.0 - 7.3 Mc. 60
    D 80 3.5 - 4.0 Mc. 80

    AUDIO OUTPUT: Two audio output circuits are provided:

    1. The loudspeaker in the NC-57 is capable of faithfully reproducing the ample audio volume delivered by the Receiver. An output transformer is mounted on the loudspeaker to match the impedance of the output tube.

    2. A Phones jack is mounted on the front panel and is wired so as to silence the loudspeaker when headphones are used.

    POWER SUPPLY: The NC-57 is designed for operation from a 105/130 volt, 50/60 cycle, source of supply. Normal power consumption is approximately 70 watts. The built-in power supply provides all voltages required by the heater and B supply circuits.

    ACCESSORY CONNECTOR SOCKET: An octal type socket is mounted at the rear of the NC-57 to permit convenient connection of external accessories. The Tuning Meter, SM-57 which is available for use with the NC-57 is fitted with a cable and plug to connect directly to this socket with no additional wiring.

    NC-57 Receiver Net $98.50

    SM-57 Tuning Meter Net $14.95

    TB-2 Tilt Base Net $3.95

    Source: Instruction Manual for The National Model NC-57, National Radio Products 1948 Catalog.

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