472kHz.org

Useful links

Antennas, ground systems

136/475kHz ATU (G0FTD)
250-400 µH variometer (G0MRF)
472 kHz small loop experiment (VK1SV)
630 m 8-circle antenna (NO3M)
630 m loaded inverted L Antenna (VK5FQ)
Antennas for 136 kHz (ON7YD) ^*
A receive only vertical (WA3ETD)
A receiving array for 160 m through 2200 m (N6LF)
A short antenna tuner (HB9DUL)
A small 500 kHz vertical antenna (G0MRF)
A versatile 630m antenna (VE7SL)
Ball variometer (DL4YHF)
Implementing an effective ATU for 630 meters (KB5NJD)
LF and MF transmitting antennas characteristics and diagrams (ITU)
LF-MF antenna notes (N6LF)
Low and medium frequency receive antennas (NO3M)
Magnetic Loop antenna for 630m (DL6RCN)
N6LF 630m Transmitting Antenna Version 2 (N6LF)
Short low- and medium-frequency antenna performance (Valentino Trainotti et al.)
Simplified calculation of ground losses in low- and medium-frequency antenna systems (Luis A. Dorado et al.)
Tee vertical antenna for the 630 m band (VK2XV)
The Low Noise Vertical (VE7SL)
The PA0RDT Miniwhip antenna (PA0RDT)
The variometer – how to make (WA3ETD)
Universal curves for soil conductivity and permittivity (N6LF)

Books

LF Today (G3XDV) A guide to success on the bands below 1MHz
MF Down Under (VK5BUG) An edited VK-compendium of articles and projects for the 630m and 160m bands

Commercial rigs

Measuring

630 m antenna matching measurements using an oscilloscope (VE7CNF)
A long-wave SWR meter (HB9DUL) ^*
A simple antenna dipper for 80 m – 630 m (and possibly also 2200 m) (WB4JWM & K4AEK)
A SWR protection circuit for FET amplifiers commonly used at MF and LF (WB4JWM)
LF VSWR meter (G0MRF) ^*
LF-HF reflection coefficient bridge (G0MRF)
Making a ScopeMatch for the LF / MF bands (VK5FQ)
Modifying an MFJ-259B antenna analyzer to operate on 630 meters (KB5NJD)
Tuning aids for the 136 kHz and 500 kHz Bands (M0BMU)

Modes, modulation

Basic forward error correction (FEC) schemes (Mark Watson)
The principle of forward error correction (Paul Nicholson)
Weak signal modes (ON7YD)

Operating

Some digital modes on MF & LF (VK5FQ)

Personal sites ^#

SO5AS/G4ASL

Propagation

630 meter daily reports (KB5NJD)
Longwave and mediumwave propagation (H. E. Farrow, BBC)
Propagation 101: The case of the X1.6 flare on 9/10/14 (KB5NJD)

Receiving

136 kHz LF and 472 kHz MF Pre-amplifiers (G0MRF)
475 kHz bandpass filter (VE7VV)
500-515 kHz preselector (W1VD)
518 kHz elliptical 50 Ohm low-pass filter (W1TAG)
A bias-T powered receive antenna preamp (WB4JWM)
A simple bandpass filter for 475 kHz (VK1SV)
Making a 472 to 479 kHz bandpass receive filter for 630 m (VK5ZVS)
Managing AM broadcast overload of an E-probe using a shunt LC network (WA3TTS)

Software

Argo (I2PHD) a DFCW and QRSS viewer
Freeware for radio amateurs (DL5WSB, sk) mini Ring Core Calculator, mini dB Calculator, ...
Opera (EA5HVK) Opera receiving and transmitting software
QRS (ON7YD) QRSS & DFCW transmitting software
Spectrum Lab (DL4YHF) Audio spectrum analyzer with waterfall display, for QRSS & DFCW reception
Winrad (I2PHD et al.) SDR amateur radio program
WSJT-X (K1JT) JT4, JT9, JT65 and WSPR receiving and transmitting software
WSPR (K1JT) WSPR receiving and transmitting software
WSQ (ZL2AFP, DL4YHF) WSQ2 receiving and transmitting software

Transmitting

0,5 kilowatts 500 kc (630 m) MOSFET PA (DJ0ABR)
0-500 kHz linear exciter (VK2XV)
100 Watt CW transmitter for the 500 kHz band (N4ICK)
100 Watt MF CW TX (GW3UEP)
137/472 kHz transmitter (W1TAG)
225 Watt 630 meter non-linear amplifier (WB4JWM)
25 Watt 472 kHz PA (GW3UEP)
400 watt FET amplifier for 630 meters (W7IUV)
472 kHz transmitter (M1GEO)
472 kHz transverter (G3XBM)
475 kHz 7 pole elliptical low pass filter (VK5FQ)
500 kHz Class-D 500-Watt RF deck (W1VD)
500 kHz CW transmitter (M1BMU)
500 Watt 500 kHz transverter (PA3BCA)
500 Watt output 4-400A linear amplifier for 600 meters (W5JGV)
5 Watt linear broadband amplifier (G0MRF)
630 m 100 watt transmitter (VK5FQ)
630 m 5-15 W amplifier (IW3SGT)
630 m low power transmitter (VK5FQ)
630 m Wilkinson power combiner (VE7SL)
6AG7/807 transmitter for 472 kHz (VK1SV)
A 100 watt linear amplifier (WB4JWM)
A 300 W Class D amplifier for 630 m (G0MRF)
A 630 m transverter, amplifier and switching arrangement (K3MF)
A simple amplifier for the Ultimate 3 for 136 & 472 kHz (HB9ASB)
A simple homebrew linear RF chain (DF2JP)
A small 'linear' power amplifier for MF (DL4YHF)
HF to LF/MF linear transverter with 500 kHz Class D EER power amplifier (M0BMU)
LF/MF, flexible, efficient, non-linear, transmit converter (VK1SV)
Long-waves and medium-waves dual-band kilowatt CW transmitter (HB9DUL)
Medium power linear power amplifier for LF/MF (G4JNT)
Menu setup for the TS-590SG for use on 630 m and 2200 m digital modes (KB5NJD)
Modifying an IC735 for the 630 m band (SQ5BPF)
SoftRock RXTX - Modification for 2200, 630 and 160 metre operation (VE7VV)
Third-Method Narrowband Direct Upconverter for the LF / MF Bands (G4JNT)
Transverter for the 630 m band (VK6YSF)
Using the Ultimate 2 on 472 kHz with an external PA (G8AGN)
VXO controlled transmitter for the UK 500 kHz Experiment (G3YMC)

Web

ON4KST chat (630 m) (ON4KST)
PSK Automatic Propagation Reporter Propagation reporter, unlike the name suggests also useable for JT9, FT8, Opera, ...
Twente WebSDR (PA3FWM et al.) Wide-band WebSDR, includes 472-479 kHz
WSPRnet WSPR propagation reporter

Other

A survey of the 630-meter band for amateur radio (KB5NJD)
Determination of soil electrical characteristics using a low dipole (N6LF)
NJDTechnologies (KB5NJD) Excellent information source for 472 kHz, with extended daily reports
The 630 meter band (VO1NO)
The ARRL 600 meter Experimental Group (W5JGV et al.)
You, too, can work 630 meters (WD8DAS)

The missing link

Do you know one or more links that should be in the above list? Feel free to contact .
Broken links can be reported to the same e-mail address.

^*: Can be used for 630 m as well.
^#: Do you want your personal site added? Just let me know (). The only conditions are that the site is not commercial and at least partially related to 472 kHz.