Receiver: National NC-183D
| Band | MDS | Blocking DR | Two-tone DR |
| | (20 kHz) | (20 kHz) |
| 80 meters | -142 dBm | 107 dB | 79 dB |
| 40 meters | -142 dBm | 110 dB | 81 dB |
| 20 meters | -136 dBm | 105 dB | 83 dB |
AM audio S/N: 43 dB
AM Audio Frequency Response: in dB, referenced to 1 kHz measurement
| 100 Hz | 200 Hz | 400 Hz | 600 Hz | 800 Hz | 1 kHz | 2 kHz | 3 kHz | 4 kHz | 5 kHz | 6 kHz |
| 0 | +1 | +1 | +1 | 0 | 0 | -6 | -18 | -28 | -39 | -47 |
AM Audio Distortion:| Mod | 100 Hz | 200 Hz | 400 Hz | 600 Hz | 800 Hz | 1 kHz | 2 kHz |
| 30% | 4.5% | 3.2% | 2.5% | 2.2% | 2.2% | 2.2% | 4.0% |
| 50% | 5.0% | 3.2% | 2.5% | 2.5% | 2.2% | 2.2% | 3.2% |
| 70% | 6.3% | 4.0% | 3.2% | 3.2% | 2.8% | 2.8% | 4.0% |
| 90% | 7.9% | 5.0% | 4.5% | 4.0% | 3.5% | 3.2% | 4.0% |
| 100% | 11% | 7.1% | 6.3% | 5.6% | 4.5% | 3.5% | 3.5% |
Notes: Maximum i-f bandwidth is about 4 kHz @ -6 dB. Before running the audio frequency response and audio distortion test the tone control was adjusted for flat response as measured through the auxiliary audio input.
AM distortion numbers show the somewhat typical increase at lower audio frequencies - most often caused by the low audio frequencies riding on the AGC line. Also there is the usual increase in audio distortion as the modulation percentage increases. This is due to the detector's inability to cleanly demodulate the higher amplitude levels although this receiver does pretty well.
Info on the measurement setups and test results on other receivers can be found at:
http://www.w1vd.com/BAreceivertest.html
