A LowFER is a low frequency radio propagation beacon (or occasionally other type of station), run by a hobbyist under FCC Part 15 rules. The word is an acronym of Low Frequency Experimental Radio.
Unlicensed LowFER operation is allowed in the frequency range 160 - 190 kHz, the so called 1750 meters band.(1) In this frequncy range transmitters may not use antennas longer than fifty feet (including any transmission line between the transmitter and the antenna). RF stage input power is restricted to a maximum of 1 W. Due to these restrictions, LowFER transmitters are usually located at the base (feeding and grounding point) of a vertical antenna.
Most transmissions consist of beacons near the high end of the band (180-190 kHz), as in the past the lower half of the band was occupied by strong signals of the Ground Wave Emergency Network (GWEN). LowFERs usualy transmit morse code telegraphy, slow speed telegraphy and various digital modes. These modes include extremely slow morse code (QRSS) and dual-frequncy CW (DFCW), which can be passed through very narrow filters and displayed visually with programs like SPECTRAN, ARGO etc. Speech transmission (AM or SSB) is also allowed but sheldomly used.
Most of the tranmitting equipment for the LowFER band is homemade, but commercial equipment becomes available occasionally. Several HF transceivers and receivers tune down to 100 kHz or lower, alternativley LF up convertes may be used for reception.
Even with such limited stations, LowFER stations have been received at distances approaching 1000 miles by listeners using sophisticated receiving setups at electrically quiet locations.
| § 15.217 Operation in the band 160–190 kHz.
(a) The total input power to the final radio frequency stage (exclusive of filament or heater power) shall not exceed one watt.
(b) The total length of the transmission line, antenna, and ground lead (if used) shall not exceed 15 meters.
(c) All emissions below 160 kHz or above 190 kHz shall be attenuated at least 20 dB below the level of the unmodulated carrier. Determination of compliance with the 20 dB attenuation specification may be based on measurements at the intentional radiator's antenna output terminal unless the intentional radiator uses a permanently attached antenna, in which case compliance shall be demonstrated by measuring the radiated emissions.
Outside North America, there is an official amateur radio allocation between 135.7-137.8 kHz. Higher trasnmitter power levels are permitted, to achieve an effective radiated power (ERP) of 1 W. This power level allows long distance two-way communications under favorable conditions and with the use of special modulation techniques.
- White, G.E.: "1750 meters - Some data on an undiscovered experimental band". CQ, April 1968, p. 31-32,120.
- Ellen White, W1YL, ed.: "ARRL Ham Radio Operating Guide", The American Radio Relay League, Newington, CT, p. 36-37, 1976.
- Steve Ford, WB8IMY: "Lowfing on 1750 meters", QST, American Radio Relay League, October 1993.
- ARRL LF (Low Frequency)
- The Longwave Club of America
- Building a LowFER beacon - "Manhattan style", by VE7SL
- Simple LowFER Transmitter, by Lyle Koehler, KØLR
- Argo: a QRSS and DFCW viewer, especially tailored for LF, but usable also for EME, by I2PHD.
- Basic 1705m transmitting antenna by Mitchell Lee.
- Lowfer QSL : A great collection of LowFER QSL cards, by W4DEX