Hallicrafters SX-117 Receiver

Hallicrafters SX-117
Performance Test

Hallicrafters SX-117


Band	MDS	Blocking	Two-tone D.R.
		(20 kHz)	(20 kHz)

80 meters	-139 dBm	108 dB	81 dB
40 meters	-138 dBm	106 dB	78 dB
20 meters	-140 dBm	107 dB	76 dB

AM Audio S/N: 44 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

-3 dB

+4 dB

+2 dB

+1 dB

0 dB

-5 dB

-9 dB

-13 dB

-20 dB

-33 dB

AM Audio Distortion:



Mod%	100 Hz	200 Hz	400 Hz	600 Hz	800 Hz	1 kHz	2 kHz

30%	71%	16%	5.6%	5.0%	5.6%	6.3%	10%
50%	63%	14%	5.0%	4.0%	4.5%	5.0%	7.9%
70%	56%	14%	5.6%	4.5%	5.6%	6.3%	7.9%
90%	56%	16%	7.9%	7.1%	7.9%	8.9%	8.9%
100%	56%	18%	8.9%	7.9%	8.9%	10%	10%

Notes: Maximum i-f bandwidth is about 5 kHz @ -6 dB.

A couple 'features' of this receiver deserve mention. The notch filter, although it has an 'off' position is never really off. The off position moves the notch frequency toward the edge of the receiver passband, but not completely out of the passband, and creates a problem for AM reception. SSB reception appears to be less affected. The notch filter was temporarily disconnected for the audio tests.

Looking at the audio distortion results one immediately notices the very poor performance at low audio frequencies. Although circuit modifications have not been attempted, one would assume that this is caused by low frequency audio riding on the AVC line. This may especially be the case with the SX-117 when one reads in the instruction manual under General Description, "Amplified fast-attack, slow-release AVC for SSB/CW; fast-attack, fast-release for AM." Fast release is precisely what not to use for clean demodulation of AM signals. See test results for the HRO-60 for more information on distortion improvement vs. AGC time constant.