| Abbreviation | Definition |
|---|---|
| SCARS | South Canadian Amateur Radio Society |
| SCATS | Southern California Amateur Transmitting Society |
| SCC | Signal Conditioning Carrier |
| SCCS | Signal Conditioning Carrier System |
| SCFM | Sub-Carrier Frequency Modulation |
| SCM | Single - Carrier Modulation |
| SCPC | Single - Channel - Per - Carrier |
| SCRRBA | Southern California Repeater and Remote Base Association |
| SEC | Gas Sampling method |
| SHO | Simple Harmonic Oscilator |
| SIR | Signal-to-Interference Ratio |
| SIT | Special Information Tone |
| SJHRC | St. Joseph High (School) Radio Club |
| SK | Silent Key |
| SKN | Straight Key Night |
| SLAPPIMNGFATARSE | EEPEPEPEPEPEPEPE |
| SMA | Satellite Master Antenna |
| SMARC | Southwest Missouri Amateur Radio Club |
| SMARS | Southern Michigan Amateur Radio Society |
| SNIO | Simultaneous Non-Interfering Operations |