30-meter band
| 30-meter band | |
|---|---|
| Frequency range | 10.100–10.150 MHz, worldwide |
| Wavelength | About 30 m |
| Group | HF |
| US license | General and above, whole band; CW and data only |
| Operating | |
| Common modes | CW, FT8 and other digital modes |
| FT8 frequency | 10.136 MHz |
| Power limit (US) | 200 W PEP output |
| Half-wave dipole length | About 46 feet (14 m) |
| Best time | Day and night; long distance best from late afternoon to early morning |
The 30-meter band, 10.100 to 10.150 MHz, is a small HF band between the 40-meter and 20-meter bands, and it borrows something from each. It is only 50 kHz wide, and in the United States it is reserved for CW and digital modes, with no voice at all. The result is one of the quietest bands on HF, popular with CW operators, low-power ("QRP") enthusiasts and FT8 users who want long-distance contacts without the crush of the larger bands.
Thirty meters is one of the three WARC bands, along with the 17-meter and 12-meter bands. The name comes from the 1979 World Administrative Radio Conference (WARC-79), the International Telecommunication Union meeting that allocated all three to amateurs; they opened to US amateurs during the 1980s. By a convention written into band plans around the world, contests are not held on the WARC bands, so 30 meters stays usable for ordinary contacts on busy contest weekends.
Propagation
Thirty meters behaves like a blend of its neighbors. During the day, the absorbing D layer of the ionosphere takes less of a toll on it than on 40 meters, so signals reach out several hundred to a couple of thousand miles. After dark the band stays open long after 20 meters has closed, and that is when it comes into its own for DX, or long-distance contacts. Intercontinental paths open in the late afternoon, last through the night, and are often strongest around sunrise and sunset along the gray line, the band of twilight that circles the earth.
The band is also less dependent on the solar cycle than the bands above it. In the low years of the cycle, when 15 and 10 meters are often closed and 20 meters shuts down early in the evening, 30 meters remains a dependable nighttime DX band. In the high years it may be open somewhere at almost any hour.
What you'll find on the band
The band plan divides the 50 kHz simply:
- 10.100–10.130 MHz is CW. DX stations and DXpeditions tend to gather near the bottom edge, with conversational CW, or "ragchewing", above them.
- 10.130–10.150 MHz holds the digital modes. FT8 is at 10.136 MHz and its faster relative FT4 at 10.140 MHz, with RTTY and PSK31 nearby.
- The band is a favorite for WSPR, a beacon mode in which stations send very low-power signals and receiving stations report where they were heard. WSPR signals cluster just above 10.140 MHz.
- There is no voice segment. US amateurs may not use voice on 30 meters, and band plans in other regions keep it essentially free of voice as well.
Non-amateur signals are heard from time to time, because amateurs share the band with fixed stations in other countries.
US privileges
Under the FCC's Part 97 rules, holders of a General, Advanced or Amateur Extra license may use the whole band; like the other WARC bands, 30 meters has no segment reserved for Extras. Technicians have no privileges here. Three further rules set the band apart:
- CW and data only. Morse code, RTTY and digital modes such as FT8 are permitted. Voice (phone) and image modes are not.
- 200 watts maximum. Transmitter output is limited to 200 watts PEP (peak envelope power), compared with the 1,500 watts allowed on most bands. A typical 100-watt transceiver is well within the limit, but an amplifier must be turned down or bypassed.
- Amateurs are secondary. The band's primary users are fixed (point-to-point) stations licensed by other countries, and amateur stations must not cause them harmful interference.
Antennas
A half-wave dipole for 30 meters is about 46 feet long, which fits in most yards. A quarter-wave vertical is about 23 feet tall and, with a good set of radials, works well for DX because it radiates at low angles. Many multiband verticals and trap dipoles include 30 meters.
Because 10.1 MHz is not a multiple of 7 MHz, a 40-meter dipole is not resonant on 30 meters, and an end-fed half-wave cut for 40 meters usually does not cover it either. A doublet, a center-fed wire fed with ladder line and matched with an antenna tuner, covers 30 meters along with its neighbors. Rotary beams for the band exist, but they are large for such a narrow slice of spectrum, and most stations do well with wire.