There are a number of methods to create an LF or MF beacon or exciter. Below are some examples of both commercially available beacon/exciter hardware, as well as roll-your-own beacons or exciters.
- QRP Labs Ulitmate3S. (verified by N4TLF) The Ultimate3s by QRP Labs (base price $29) is a small beacon that can produce 1/4W-2W on frequencies between 136kHz and 2 Meters. It uses a Silicon Labs Si5351 controlled by an ATGMega328 (same chip as an Arduino Uno). It can automatically correct for frequency drift using an optional GPS receiver. The Ultimate3s operates several modes.
- Whisperino 630M autonomous WSPR transmitter. This is a homebrew Arduino Uno & AD9850 based beacon transmitter and small IRL 510 amplifier. Not tested yet by AMRAD.
- “Classie” Simple WSPR transmiter. While this transmitter is not specifically for LF/MF, it is a simple design using an Arduino Uno and NT7S Si5351A breakout board. A BS-170 is the output stage. Not tested yet by AMRAD.
- W3PM DDS & SI5351 WSPR beacon and misc projects. W3PM has created several projects based on Arduinos and both AD9850 and Si5351A. Not tested yet by AMRAD. GPS calibration is included with some projects.
- QRP Labs Ultimate Arduino Shield kit. This is a basic Arduino Uno shield kit ($12) that can hold the QRP Labs Si5351A sub-board (or possibly a Type II AD9850 DDS module) and low-pass filter. There is room for up to three BS170 FETs as amplifiers, and a GPS can be connected for frequency disciplining. Software is available for most modes, but NOT WSPR. N4TLF has one of these on order.
- MF Solutions/NJD Technologies 630 meter transmit downconverter. This transmit downconverter takes the signal from an 80 meter rig and down converts it to the 630 meter band. MF Solutions designs and sells it, but see the NJD Technologies website for more information. It has an optional 10 MHz reference input. Approx. $80. AMRAD has not tested this unit yet.
- Simple Lowfer Transmitter. While this transmitter is designed for the lowfer band at 160-190 kHz, the design concept can be used of many other LF/MF/HF frequencies. The design can be modified an number of ways, based on the output frequency of interest, the crystal/oscillator frequency, and logic chips available. Of interest is the low-power push-pull output stage. By Lyle Koehler, KØLR. This design has not been used by AMRAD yet.
- Altoids Tin LowFER Transmitter. Another Lowfer exciter/low-power transmitter. This design uses a transistor oscillator followed by a digital frequency divider and BS170 (or similar) amplifier. It includes a PicAxe that is programmed with a message to send in QRSS. AMRAD has not tested this design yet. A LowFER antenna tester is also shown on the same page. By Techlib.com.