TMC GPR-90 Performance Test

TMC GPR-90

TMC GPR-90

Band MDS Blocking Two-tone D.R.
(20 kHz) (20 kHz)
 
80 meters -140 dBm 111 dB 85 dB
40 meters -139 dBm 108 dB 81 dB
20 meters -139 dBm 107 dB 75 dB

AM Audio S/N: 45 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
 
0 dB +1 dB +1 dB +1 dB 0 dB 0 dB -3 dB -7 dB -12 dB -17 dB -21 dB

AM Audio Distortion:

 
Mod% 100 Hz 200 Hz 400 Hz 600 Hz 800 Hz 1 kHz 2 kHz
 
30% 2.2% 1.6% 1.6% 1.6% 1.8% 1.8% 2.8%
50% 2.8% 1.6% 1.4% 1.8% 2.5% 3.5% 5.0%
70% 10% 8.9% 8.9% 10% 10% 11% 13%
90% 18% 16% 16% 16% 16% 16% 18%
100% 20% 18% 18% 18% 18% 18% 20%

Notes: Maximum i-f bandwidth is about 11 kHz @ -6 dB. Before running the audio frequency response and audio distortion test the audio selector control was adjusted for 'normal' and audio spread was set for 'wide'.

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.