The 9 MHz Mystery Explained! Why We Use USB & LSB скачать в хорошем качестве

The 9 MHz Mystery Explained! Why We Use USB & LSB

Amateur radio operators follow a long-standing convention when operating single sideband (SSB): they use Lower Sideband (LSB) on the 160, 80, and 40 meter bands (below 10 MHz), while using Upper Sideband (USB) on the 20, 15, and 10 meter bands (above 10 MHz). The Technical Origins This practice stems from technical limitations in early SSB equipment design. Many early amateur SSB rigs utilized a 9 MHz IF (Intermediate Frequency) system, and with this design, it was simply easier and more cost-effective to generate LSB below 9 MHz and USB above 9 MHz. As one source explains, "The old ham convention of LSB below 20m, USB 20m and up came from the common use of 5 MHz in early SSB rigs" and the "9 MHz IF that was old and commonly available" when these radios were being developed. The 10 MHz Dividing Line The convention has solidified around 10 MHz as the dividing point. Generally, bands above 10 MHz use USB, while bands below 10 MHz use LSB. This practice is so established that it has become a standard operating procedure in amateur radio. Why This Convention Persists While modern radio equipment doesn't face the same technical constraints as older rigs, the convention remains firmly in place. This is largely due to operator habit and the desire for consistency within the amateur radio community. Even with today's advanced digital radios that can generate either sideband with equal ease, operators continue to follow this tradition to maintain compatibility and avoid confusion when making contacts. This is another example of how amateur radio balances technical evolution with established operating practices that have proven effective over decades. #AmateurRadio, #HamRadio, #SSBOperation, #LSBvsUSB, #HamRadioTechniques, #9MHzIF, #RadioHistory, #HFBands, #HamRadioTips, #160Meters, #80Meters, #40Meters, #VintageRadio, #HamCommunity, #RadioFrequency, #SidebandOperation, #RadioTechnology, #ElectronicHistory, #RadioHobby, #AntennaOperation