What is a common repeater frequency offset in the 70 cm band?

• A. Plus or minus 5 MHz
• B. Plus or minus 10 MHz
• C. Plus or minus 7.6 MHz
• D. Zero offset

Answer: (A)

In the 70 cm band, which ranges from 420 MHz to 450 MHz, the common repeater frequency offset is typically plus or minus 5 MHz. This offset is standardized to avoid interference between repeaters that are within close proximity to each other, ensuring that they operate effectively without causing confusion or signal overlap.

The significance of this 5 MHz offset is rooted in the way FM repeaters function; they receive signals on one frequency and transmit on another, with the offset facilitating clear communication paths for different users. This means that if a repeater is operating on an input frequency of, say, 446.000 MHz, it will usually transmit its output on 441.000 MHz (5 MHz lower), or conversely, it might receive on 441.000 MHz and transmit on 446.000 MHz (5 MHz higher).

This standardization is a vital aspect of ham radio operations in the 70 cm band for both new operators and experienced ones, promoting safety and clarity in communications. Understanding this offset is crucial for effective use of local repeaters and ensures that operators can connect easily and reliably within the band.