Had a chance to make measurements on a precision full-wave AM detector yesterday. The detector used for the test was described by K2CU some time ago on AMfone and had been in daily use on the 455 kHz output of my R-390A ... until the changeover to the SoftRock demodulator.
The R-390A was operated in the 16 kHz BW position and MGC mode - same as for the SoftRock testing. Operating in MGC mode provided a convenient means to adjust the input level to the detector. Performance remained essentially the same over a wide range of input levels.
Information on the detector can be found here:
http://www.amwindow.org/tech/htm/alowdisdet.htm Receiver: R-390A / K2CU Precision Full-wave AM Detector
AM audio S/N: 42 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 |
| +1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
AM Audio Distortion:| Mod | 100 Hz | 200 Hz | 400 Hz | 600 Hz | 800 Hz | 1 kHz | 2 kHz |
| 30% | 1.4% | 1.4% | 1.4% | 1.4% | 1.4% | 1.6% | 1.6% |
| 50% | 1.1% | 1.4 | 1.6% | 1.6% | 1.6% | 1.6% | 1.6% |
| 70% | 1.0 | 1.1 | 1.4% | 1.4% | 1.4% | 1.4% | 1.4% |
| 90% | 1.0 | 1.4 | 1.4% | 1.6% | 1.6% | 1.6% | 1.8% |
| 100% | 1.1 | 1.6 | 1.8% | 1.8% | 1.8% | 1.6% | 2.2% |
