TMC GPR-90 Receiver

TMC GPR-90 Performance Test

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

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.