10 meter AM / FM calling frequency
The 10 meter ham radio band has a suggested FM calling frequency of 29.6 MHz, which is nestled among the repeater frequencies. With a dedicated 10 meter FM band antenna tuned for the 29.5 - 29.7 MHz range, this works fine. However, many 10 meter operators primarily use CW, data, SSB, and similar modes in the 28.0 - 28.5 MHz range. Most popular 10m antennas such as a dipole antenna or 1/4 wavelength vertical antenna tuned for say 28.3 MHz may have an excessively high SWR at 29.6 MHz. Operators using inexpensive converted 27 MHz CB radios may not be able to tune the non-5kHz offset channel. That is, they might be able to tune to 29.605 MHz, but not 29.600 MHz.
The 10m AM mode calling frequency is generally 29.0 MHz, which is much closer to the 28 MHz SSB/CW frequencies. This allows more efficient use of the same antenna for both 10m SSB/CW and AM. An AM channel offset as much as 5 kHz can generally still be heard by another AM receiver, but with reduced signal efficiency. 10 kHz AM channel spacing is generally adequate for AM radios (as observed by CB radio channel plans and MW AM broadcast plans).
It is worth considering a “new” FM calling frequency near but just above 29 MHz with a 5 kHz offset to address using inexpensive converted CB radios and more optimally using the same antenna as for 28 MHz SSB/CW. We suggest considering 29.055 MHz as a new 10 meter FM calling frequency. This is far enough away from the AM calling frequency of 29.0 MHz and typically working frequencies just above 29.0 MHz.
In this table, the “converted CB channel” assumes common export radio channel charts. The specific radio may have a different channel number for the same frequency. We’ve put in a possible “new” AM calling frequency of 29.005 MHz for converted CB radios, if such would be desired. The jump in channel sequencing from channels 23, 24, 25 is a de facto standard.
| frequency (MHz) | mode | description | converted CB channel |
|---|---|---|---|
| 29.000 | AM | 10 meter AM calling frequency | |
| 29.005 | AM | AM calling freq. for converted CB radios | 20 |
| 29.015 | AM | AM working frequency 1 | 21 |
| 29.025 | AM | AM working frequency 2 | 22 |
| 29.035 | FM | FM working frequency 1 | 24 |
| 29.045 | FM | FM working frequency 2 | 25 |
| 29.055 | FM | 10 meter FM calling frequency | 23 |