A modern, general coverage receiver for commercial, military, and amateur communications, incorporating a total of vitally important features available in no other competitive equipment. Tuning range is 540 kc to 31 mc in 7 bands, with dual conversion on all frequencies above 7 mc. Its unique design provides maximum flexibility of operation to satisfy a wide variety of communication requirements. The NC400 may be used as a self-contained unit, either manually tuned or crystal controlled on pre-selected frequencies. In addition, external master oscillator provisions make possible use of modern synthesizer techniques for applications were extreme frequency stability is required. It may be operated in space or frequency diversity applications. Provisions are made for interconnection of any required outputs or for feed to external loads of combiners. All frequency determining circuits may be internally or externally controlled. The NC-400 also provides optimum versatility of bandwidth, either though the use of internal IF circuits or the use of optional mechanical filters.

Band 1 .54 - 1.1 MC
Band 2 1.1 - 2.1 MC
Band 3 2.1 - 4.1 MC
Band 4 4.1 - 7.1 MC
Band 5 6.9 - 12.2 MC
Band 6 11.8 - 20.4 MC
Band 7 19.6 - 31.0 MC

1st RF Amp 6BZ6
2nd RF Amp 6BZ6
1st Mixer (455kHz) 6BE6
1st Mixer (1730kHz) 6BE6
2nd Converter 6BE6
HF Osc 6BZ7
1st IF Amp 6BA6
2nd IF Amp 6BA6
3rd IF Amp 6BA6
Fil. Reg 4H4C
AM Detector/ANL 6AL5
Het Det. 6BE6
Manual NL 6AL5
S-Meter/1st Audio 12AT7
Audio Amp 6AQ5
Voltage Regulator 0B2
Rectifier 5U4GB

FREQUENCY STABILITY: Long term stability after warmup - .002%

SENSITIVITY: 1 microvolt for 10 db signal/noise ratio

SELECTIVITY: 4, 8 and 16 kc positions provided with 6 tuned circuits. 3.5 kc upper and lower sideband positions provided with 14 tuned circuits. 3.5 kc sharp position activated plug-in crystal filter providing 5 additional degrees of selectivity below 3 kc plus phasing notch. Plug-in accessory available which will provide front panel selection of three mechanical filters without modification of receiver. Proper choice of filters will enable selection of bandwidths form 500 cycles to 16 kc, or will enable filter type of sideband selection from front panel.

SSB PROVISIONS: Separate SSB heterodyne detector uses pentagrid converter and spinate beat oscillator. Beat oscillator may be crystal controlled. Special "fast attack-slow release" AGC circuit. Sideband selection accomplished by exclusive, new National pass band switching techniques. In the event of commercial-type SSB reception, single sideband mechanical filters may be installed and switched from front panel.

FIXED CHANNEL OPERATION: HF oscillator has 5 crystal sockets for use in fixed channel operation, Channels may be selected by front panel switch, In addition, HF oscillator may be controlled form external master oscillator selected by front panel switch. "S" meter "Tune"positions permits rapid tuning of receiver to crystal controlled channel.

DIVERSITY PROVISIONS: Basic receiver may be operated form master oscillator as noted above. An accessory Diversity Modification Kit (NC400 DMK) allows choice of internal or external control of all oscillators. Rear panel selector provisions make possible use of any receiver either as master control, or slave fed form other oscillator sources, IF, detector and AGC outputs available for feed to external loads or combiners.

POWER REQUIREMENTS:110-220 volts, 50-60 cycles AC



  • XCU-400 crystal calibrator. Output frequencies of 100 kc. and 1 mc.

  • NTS-2 matching speaker

  • NC-400 DMK diversity modification kit

  • NC-400 FH mechanical filter housing

    Photo courtesy of N4QB

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