From the Ten-Tec Reflector November 1, 1999
- 200's are for accessory items - antenna tuners, filters, dummy loads, etc.
- 300's we have used for "connecting" items - cables and remote knobs.
- 400's are linear amplifiers
- 500's are transceivers
- 600's are keyers and keying devices
- 700's are microphones and SSB related devices.
- 800's Scout modules
- 900's are power supplies
Over the years, a few items have strayed from this (like the use of 200 series numbers for older power supplies/mics) but it has been fairly consistent for the last 10 years or more.