136 kHz band
The 136 kHz band was made available to UK amateurs on 30 January 1998 and covers
just 2100 Hz (2.1 kHz), from 135.7 - 137.8 kHz (about 2,200 metres). The power limit
in the UK is 1 watt effective radiated power (ERP).
136 kHz is well-suited to radio experimenters with an interest in antennas
and the home construction of transmitting and receiving equipment. The most common
modes in use are normal CW using conventional morse code (frequently within the range 8 to
15 words per minute), and very slow CW (known as QRSS).
Even if you don't have much space for erecting antennas, you will be
surprised what can be achieved by putting up antennas similar in size to those used for
the short wave bands. Experimentation on this band can be enjoyed by both short wave
listeners (SWLs) and by those licensed to transmit on the new band.
The best time to listen for stations on 136 kHz is on Saturday and Sunday
mornings, when activity is highest. Start by listening in the CW segment, 136.0 -
137.4 kHz. You may also hear very slow morse transmissions (QRSS) in the range 137.6
- 137.8. However, with a morse 'dot' duration of around 3 to 30 seconds, QRSS is
hard to decode by ear! In practice, QRSS is decoded on a PC using software that
displays the marks and spaces of the morse characters on the computer screen. Thus QRSS
signals are often said to be 'seen', rather than 'heard'! The very long dot length
allows signals to be detected (seen) at signal levels some 15 dB below the noise level.
I am in an elevated part of Chepstow, south east Wales;
about 70 m above sea level (ASL) with a good 'take-off' to the south and the east.
For a detailed street map of my location, click here
For an OS map (1:50,000) of my location, click here
How I got interested
It was Dave, G3YMC, who got me interested in the low frequency (LF) bands. By the
time the 136 kHz band became available, Dave had already been experimenting with receive
converters for 73 kHz. Dave showed me how easy it was to build an LF converter for
use with a 10 MHz receiver and was in the process of modifying his converter for 136
kHz. I was soon hooked. (After 6 years of doing an Open University degree
course, I was itching to get back into some home-construction projects!)
The new 136 kHz band presented an opportunity to build an amateur radio station for a
band where there was very little commercial equipment available. When I started
constructing my LF station in February 1998, I had no TX; RX; or RF test/measuring
equipment for the LF part of the radio spectrum - so there was much to be done!
First out of my workshop came an LF dip oscillator; LF SWR bridge; transverter;
100 W PA (later followed by a 400 W PA); and, of course, the antennas.
This picture shows Wil operating as MW/PA0BWL from the GW4ALG shack. The picture,
taken in October 2000, shows Wil working Werner ON6ND. The QSO was made on CW
using 400 watts to my 12 m experimental vertical.
Exciting times for amateur experimenters
My initial tests were carried out using an old Yaesu FT707 transceiver (operating at 10
MHz) with my homemade transverter (136 kHz transmit/receive converter). Just 15
watts RF output from the transverter into a tuned loop antenna was enough to get an S5
report from Brian GW0GHF over a distance of 42 km. On receive, I was delighted and
amazed to hear a number of stations such as G2AJV; G3XTZ; and G3LDO - all greater than 150
km away! 136 kHz was indeed looking like a band with some potential!
One of my most memorable contacts on 136 kHz was with Graham G3XTZ. Graham was
one of the first stations to report hearing my transmitter test signals. Then, on
21st March 1998, we made the first England to Wales 2-way contact over a distance of 157
km - an amazing distance for such little power; probably just a few milliwatts ERP.
Later, my contact with OH1TN in November 1998 established, at the time, a new
world distance record on 136 kHz (1915 km) and remained the UK distance record for over 12
You can do it too! Start constructing your LF station today!
Since those early days on 136 kHz, the sharing of ideas and test results has
enabled a small, but growing number of LF enthusiasts to generate greater power levels on
transmit; improve the reception of weak signals; and increase the efficiency of their
Within these pages, you can discover how, from a small back garden in Chepstow, I made
record-breaking contacts with over 14 countries - and how I made contacts with other LF
stations over distances that I thought would be 'impossible' when I made my first
tentative test transmissions on 136 kHz back in March 1998.
General information and references relating to 136 kHz can be found via the
hyperlinks at the bottom of this page. Information about the transmitting and
receiving equipment at GW4ALG can be found via the hyperlinks at the top of this page.
Good luck on 136 kHz!
Steve Rawlings, GW4ALG
03 October 2001