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Surecom KT-8900D S-Meter

Recently I bought a cheap Surecom radio for 2m and 70cm. Unfortunately, this radio has no proper S-Meter, only a number that indicates the signal strength. In this article I tried to create a translation table to S-Levels.

IARU Standard

Measured with no modulation. Surecom directly connected to signal generator with 40cm RG223 cable. Frequency was the band midpoint (145MHz on 2m, 435MHz on 70cm)

S-Level dBm Surecom value 2m Surecom value 70cm Note
S9+60dB -33 127 107
S9+50dB -43 113 98
S9+40dB -53 107 89
S9+30dB -63 98 79
S9+20dB -73 88 96
S9+10dB -83 78 59
S9 -93 68 49
S8 -99 62 <48
S7 -105 56 <48
S6 -111 50 <32
S5 -117 <48 <32
S4 -123 <48 <32 Squelch @ Level 1 opens on 70cm
S3 -129 <48 <32 Squelch @ Level 1 opens on 2m
S2 -135 <32 <32 AF: 1kHz, Dev.: 3kHz; Modulation starts to be audible @ -130dBm
S1 -141 <32 <32 There is something in the noise ๐Ÿ˜‰

The Shurecom values seem to be in dB since the step size in dBm is equal to the value change on the radios display. I would say the receiver is not bad but the receiving level indicator is quite useless when calibrating to IARU standards. Nevertheless, many "good" radios also do not comply with the IARU standard, so I tried to find my own S-meter definition for the Surecom.

My Standard

I defined the value "100" as S9 on 2m and 70cm. Then I searched for the input level at wich the Surecom shows "100". In the next step the input levels for all other S-Levels were calculated and the corresponding Surecom values were measured. All measurements were taken with 1kHz frequency modulation @ 3kHz deviation.

This is not a great standard because most stations would be around S2-3 at my QTH. I have to compare the Shurecom to another radio in the future.

2m

S-Level dBm Surecom value
S9+30dB -30 127
S9+20dB -40 113
S9+10dB -50 109
S9 -60 100
S8 -66 94
S7 -72 89
S6 -78 83
S5 -84 77
S4 -90 71
S3 -96 65
S2 -102 59
S1 -108 53

70cm

S-Level dBm Surecom value
S9+30dB -11 127
S9+20dB -21 112
S9+10dB -31 104
S9 -41 100
S8 -47 94
S7 -53 89
S6 -59 83
S5 -65 77
S4 -71 71
S3 -77 65
S2 -83 59
S1 -89 53
last edited a month ago