Section 11.3: LF, MF, and Experimental Use #

Location matters most on the two lowest amateur bands, both below the AM broadcast band. The 630-meter band covers 472–479 kHz, and 2200 meters covers 135.7–137.8 kHz. Electric utilities use these frequencies too, for power-line carrier (PLC) systems that send control signals along transmission lines. To protect those systems, an amateur station on either band may operate only from a fixed location, and the utilities get to check that location first.

Notify Before Transmitting #

The check goes through the Utilities Technology Council (UTC), a trade group for utilities. Part 97 still uses its former name, Utilities Telecom Council. UTC compares your antenna’s location with the power lines that carry PLC signals on these bands. No amateur station may operate within 1 kilometer of one, measured horizontally from the antenna.

Key Information:

• Before transmitting on the 630- or 2200-meter bands, operators must inform the Utilities Technology Council (UTC) of their call sign and the coordinates of the station.
• After notifying UTC, operators may begin operating after 30 days, provided they have not been told that their station is within 1 kilometer of PLC systems using those frequencies.

You don’t need an approval letter. Your notice also lists the bands you plan to use.

Power and Emissions #

On these bands, the limit that usually matters is what the antenna radiates, not what the transmitter puts out. A quarter-wave vertical for 2200 meters would stand about 550 meters tall, higher than the Empire State Building. Practical antennas here are tiny compared with a wavelength, and their low efficiency can make the radiated power much smaller than the input power. To find EIRP, combine the power reaching the antenna with the antenna’s gain relative to an isotropic radiator, as in Chapter 6.

Key Information:

• The maximum power permitted on the 2200-meter band is 1 W EIRP.
• Except in some parts of Alaska, the maximum power permitted on the 630-meter band is 5 W EIRP.

In Alaska, stations within 800 kilometers of the Russian Federation are limited to 1 W EIRP on 630 meters. Separate transmitter limits also apply: 1500 W PEP on 2200 meters and 500 W PEP on 630 meters. A station within the transmitter limit can still exceed the much lower EIRP limit.

For example, if 100 W reaches an antenna with a gain of −20 dBi, its power gain as a ratio is 0.01. The EIRP is $100\times0.01=1$ W, exactly the 2200-meter limit. Use a defensible antenna-gain estimate rather than assuming that an inefficient-looking antenna must be below the limit.

Narrow as it is, the 630-meter band is not reserved for CW and data.

Key Information: Phone emissions are permitted in the entire 630-meter band.

The complete emission still must fit within 472–479 kHz and meet its emission standards. A phone signal near either edge needs the same edge check as on 20 or 75 meters.

A Separate Permission for Experiments #

Contributing to the advancement of the radio art is one of amateur radio’s stated purposes. Most experiments fit within normal privileges. One that needs more may get a separate, temporary permission, with its own limits on frequency, power, place, and time.

Key Information: The FCC might issue a Special Temporary Authority (STA) to an amateur station to provide for experimental amateur communications.

An STA covers only the activity it names. Ordinary operation on 2200 and 630 meters needs only the band rules and the UTC notice.