Hallicrafters SX-28A
Performance Test

Hallicrafters SX-28A

Hallicrafters SX-28A

Band MDS Blocking Two-tone D.R.
(20 kHz) (20 kHz)
 
80 meters -140 dBm 102 dB 60 dB
40 meters -139 dBm 103 dB 57 dB
20 meters -139 dBm 108 dB 58 dB

AM Audio S/N: 52 dB




AM Audio Frequency Response:

 
100 Hz 200 Hz 400 Hz 600 Hz 800 Hz 1 kHz 2 kHz 3 kHz 4 kHz 5 kHz 6 kHz
 
+2 dB +1 dB 0 dB 0 dB 0 dB 0 dB 0 dB 0 dB 0 dB 0 dB -2 dB

AM Audio Distortion:

 
Mod% 100 Hz 200 Hz 400 Hz 600 Hz 800 Hz 1 kHz 2 kHz
 
30% 4.0% 2.0% 1.6% 1.4% 1.4% 1.4% 1.4%
50% 5.6% 2.5% 1.4% 1.3% 1.2% 1.2% 1.3%
70% 10% 2.8% 2.2% 2.2% 2.0% 2.0% 2.5%
90% 18% 18% 16% 14% 14% 14% 14%
100% 22% 20% 18% 18% 16% 16% 16%

Notes: Maximum i-f bandwidth measured about 14 kHz @ -6 dB on this receiver. Before running the audio frequency response and audio distortion test the tone control was adjusted for flat response with the bass switch "in".

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.