| CatID |
Category |
| 1.1 | antennas and transmission lines - general |
| 1.2 | antennas and transmission lines - high-frequency antennas |
| 1.3 | antennas and transmission lines - vhf antennas |
| 1.4 | antennas and transmission lines - matching and tuning |
| 1.5 | antennas and transmission lines - towers and rotators |
| 1.6 | antennas and transmission lines - transmission lines |
| 2 | audio |
| 3 | commercial equipment |
| 4 | computer-aided design |
| 5 | construction techniques |
| 6 | digital techniques |
| 7 | features and fiction |
| 8 | filters |
| 9 | fm and repeaters |
| 10 | hazards |
| 11 | integrated circuits |
| 12 | keying and control |
| 13 | measurements and test equipment |
| 14 | microprocessors, computers and calculators |
| 15 | miscellaneous technical |
| 16 | novice reading |
| 17 | operating |
| 18 | oscillators |
| 19 | packet |
| 20 | power supplies |
| 21 | propagation |
| 22.1 | receivers and converters - general |
| 22.2 | receivers and converters - high-frequency receivers |
| 22.3 | receivers and converters - vhf receivers and converters |
| 22.4 | receivers and converters - test and troubleshooting |
| 23 | RTTY |
| 24 | satellites |
| 25 | semiconductors |
| 26 | single sideband |
| 27 | software |
| 28 | television |
| 29.1 | transmitters and power amplifiers - general |
| 29.2 | transmitters and power amplifiers - high-frequency transmitters |
| 29.3 | transmitters and power amplifiers - vhf and uhf transmitters |
| 29.4 | transmitters and power amplifiers - test and troubleshooting |
| 30 | troubleshooting |
| 31.1 | vhf and microwave - general |
| 31.2 | vhf and microwave - antennas |
| 31.3 | vhf and microwave - receivers and converters |
| 31.4 | vhf and microwave - transmitters |
| 31.5 | vhf and microwave - microwave techniques |
