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Contents UNESCO World
Heritage Site Grimeton Radio The Software
Defined Receiver: SAQrx First Steps
Preparing for Reception Listen to World Heritage Grimeton Radio (SAQ)
Grimeton
Radio is the last transmitter in the world generating rf power without any
electronic parts. No tubes, no semiconductors, only an engine driving an AC
generator. Receiving Grimeton Radio (SAQ) on 17.2 kHz is as easy as the
sketch below depicts:
You only
need to connect an active antenna or some aerial wire to the sound card of
your PC and to install SAQrx, a software defined VLF receiver by SM6LKM
for the VLF band below 22 kHz. UNESCO World Heritage Site Grimeton Radio (SAQ)
Grimeton
Radio (SAQ) is the last transmitter in the world preserved that generates VLF
radio frequencies with an alternating current generator (alternator), i. e. a
machine that nowadays is only known to produce AC current with frequencies
below 100 Hz – electric power. After its inventor, a Swedish engineer, this
type of transmitter is called Alexanderson Alternator (see Fig. 2 below).
From the late 1860s to 1930 about 1.2 million
unemployed people left Sweden to seek good fortune in the big cities of
America. Grimeton Radio with the call sign SAQ was built in the 1920s to
maintain communication between the Swedish emigrants and their home country.
For years the transmitter was operated as a transatlantic telegraphy link to
the RCA transmitter Radio Central in Long Island, New York, USA. With the
advent of tube transmitters and rising knowledge of worldwide propagation of
short waves, VLF transmitters became less important. Grimeton Radio was
adopted by the Swedish navy to communicate with submarines for the next
decades and so could survive until the end of the 20th century. It
was finally put out of service in the year 1995 – fully operative with 200 kW
output and the last of its kind in the world. As early
as 1996, Grimeton Radio was declared to be a national heritage of Sweden and
in the year 2004 it became a UNESCO World Heritage Site.
Grimeton Radio
(SAQ) is activated in cw transmission by the Alexanderson Society at least two times
a year, at the beginning of July around the Alexanderson Day and on christmas
eve (look out for skeds).
These are
the rare moments, when US swls and hams have the opportunity to prove that
the old lady in Sweden still can be copied at the east coast of the USA.
Reports (from everybody, not only US hams!) are rewarded by qsl cards. Have a
look at some videos on this site and
decide for yourself if it might be an exciting experience to listen to
Grimeton Radio on 17.2 kHz. The Antenna
Don’t waste
much thought on creating a resonant antenna – the half wave length at 17.2
kHz is 8700 meters, much too long for your garden. And don’t think your
antenna is meant to last forever with
a King Kong approved fastening and measures for lightning protection. You just need the antenna
for half an hour two times a year, so clamp a wooden holder for an active antenna into your shack window (see Fig. 1).
Try the PA0RDT mini whip – it comes ready to use
from a friendly Dutch radio amateur and is very tiny. If you want to use an aerial wire with a preamplifier, bend it to the
radiator beneath your window and get the other side attached to a tent peg in
the ground or to a tree or elsewhere. Maybe you
want to try a ferrite rod antenna. Our ancestors used it with great effort
for long wave reception. Antennas successfully
used by US stations reach from a 4 foot loop portable on Port Mahon Beach
(Dover, Delaware) to a 100 meter long zepp at 22 meters height at Marietta,
Ohio. Find your own solution and don’t give up after the first try! The Software Defined Receiver: SAQrx
SAQrx is
a sound card based receiver software by Johan Bodin, SM6LKM, originally covering
the frequency band from 0-22 kHz and running under Microsoft Windows. It
requires a sound card capable of full duplex at 44 kHz sampling rate
(satisfied by most of the onboard PC sound cards). Roland
Fröhlich, a mathematician and active long-/shortwave listener, extended the
capabilities of SAQrx with lots of convenient features. You can now use sound
cards up to 192 kHz sampling rate, change between modes (CW, SSB, AM), store
and play soundfiles and much more. Please read his introduction
to SAQrx to learn what options are included. Once you have
unzipped the zip file and started SAQrx*.exe, you will have a panoramic view
of the frequency band decoded by your sound card (see screenshot
below). Press [Help] to learn how to tune the receiver and change the
bandwidth. You can download the files
needed from Roland’s web site.
First
Steps Preparing for Reception of SAQ
For a
first test, you should try to find a military transmission somewhere in the
band pass of SAQrx. In Europe, there are several navy stations between 18 kHz
and 22 kHz transmitting a constant FSK idle signal. On weekdays, you may find
them transmitting information using a two-tone or multi-tone FSK mode. Even
at parts of the spectrum being quiet on other days, you may discover data transmissions.
From time to time, there is a RTTY signal (? 45 baud) on 18.1 kHz,
maybe transmitted by UFOE, a Russian navy station. Troubleshooting
If you
are using a laptop computer on batteries, the reception may be affected by
interference. Try to connect the shielding of your coax cable or the RFGND
jack of the SAQ preamp to an rf or a power line ground connection. |
