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MFJ’S 784B Programmable Digital Signal
Processor can take out just about any interference.
Helps dig out the weakest signals and
improves SWL enjoyment. (Courtesy: MFJ
Enterprises)
WR G303 PC-based radio is a sophisticated
shortwave-only radio at the same price. Both
models are available as an internal card or an
external box and are priced around $500. It’s
a way for SWLers to get a lot more receiver
for their money. Of course, your computer
has to be up to supporting this computercontrolled
radio.
Extended Range of Your
Receiver
While the shortwave bands start at 1.8
MHz and end at 30 MHz, many receivers
are capable of tuning in frequencies below
or even above those frequencies. Most portable
shortwave radios include the AM and
FM broadcast bands and many include the
longwave (LW) frequencies (50 to 540 kHz)
as well. Many desk top (i.e., expensive)
shortwave receivers tune from as low as 30
kHz to 30 MHz with some tuning as high
as 60 MHz. Most desktop receivers do not
include the FM broadcast band.
If your radio is capable of tuning LW,
don’t be surprised if you don’t hear anything.
These frequencies are home to low
power beacon transmitters which send only
two or three letters in Morse code (CW) as
identifiers as well as powerful stations for
international broadcasters from Europe and
Africa which, because of the distances and
extremely low frequencies, take extraordinarily
long antennas to pick up. Even then,
they are mostly heard only at night and
during the depths of winter.
If your radio is capable of tuning above
30 MHz, it gets into the low end of the VHF
band (home to some local public service
agencies such as police and fire departments),
and will work best with a ground
plane antenna similar to a CB antenna.
Since most agencies have long since moved
to higher VHF and UHF frequencies, there
may be little active radio traffic in your area
on these frequencies.
There is one
amateur radio band,
the six meter band
from 50 to 54 MHz,
over which you may
hear transmissions
in CW, as well as
single sideband
(SSB) AM, and
some digital modes.
For best reception of
this band, you will
need a multi-element
beam antenna
with the elements
A little help for your
receiver. MFJ’s 956
LW/MW/SW Preselector/Tuner
matches your
receiver to the antenna
to improve reception
and minimize intermodulation.
(Courtesy:
MFJ Enterprises)
10 MONITORING TIMES January 2005
horizontally polarized. This band is active
year ‘round with long distance (DX) openings
occurring during the summer months
along with TV and FM band DX.
Shortwave Listening
Antennas
Unlike portable SW radios, most desk
top receivers have no built-in antenna. It’s
assumed that you will be using an outside
antenna. So, what type of antenna is best for
shortwave reception? Can you make your
own antenna? What can you do if you can’t
have an outdoor antenna?
Almost any short length of wire will
work as a shortwave antenna. That’s because
you don’t need much of an antenna to pick
up the powerful international broadcasters.
That’s why those little whip antennas on the
portable radio seem to work so well. They
fall short on delivery when you’re trying to
tune in something more esoteric with a lot
less power. However, simply adding a long
antenna wire to a poor SW receiver may end
up creating more problems, like swamping
the receiver with the big broadcasters or
introducing spurious signals from nearby
out of band transmitters.
For serious shortwave listening you
need a serious antenna. There are several
on the market including the Grove Skywire,
a 66-foot antenna. Another ready-made antenna
is the PAR End
FedZ, which is a 45-ft
long antenna that also
comes ready to install
(see review in MT 9-
03, pages 82-83). All
you’ll need to supply
is enough coax to go
from your receiver to
the antenna. (Grove’s
coax comes with “F”
connectors, so you’ll
need a PL-259 adaptor
for the antenna
MFJ Enterprises’
54” active Outdoor
Antenna brings you
big signals in tight
spaces. (Courtesy:
MFJ Enterprises)
DIYer’s Special: Radio Shack’s external antenna
kit has all you need for an external antenna
for just $10.49. (Courtesy Radio Shack)
and possibly one for your receiver.) The
advantages of the PAR antenna is that it
brings very little extra noise to the receiver,
making it even easier to tune in the weak
ones.
You can make your own antennas. In
fact, Radio Shack has an SWL antenna kit
which contains 70-ft of antenna wire, 50-ft
of lead-in wire, and insulators for $10.49.
It’s at your local RS store as catalog #278-
758. There are many other good antenna
designs which are not hard to make and
can be found in many antenna books. The
American Radio Relay League (ARRL)
sells several books on the subject in their
free publications catalog (call 888-277-
5289). You can also check out the SW
antenna primer on the Grove web site at
http://www.monitoringtimes.com/html/
mtantennaprimer1.html.
But, what if you live in an area where
outside antennas aren’t allowed or there’s
simply no space? That’s where an active
indoor antenna might save the day. MFJ Enterprises
offers several active tuned indoor
antennas: the MFJ-1020C covers .3 to 40
MHz and may be used as an antenna preselector
when an external antenna is attached.
The MFJ-1024 is a vertically mounted 54-
inch active outdoor antenna which could be
used on a balcony and tuned from indoors.
Secrets of Better
Shortwave Listening
Almost any shortwave receiver will
benefit from several available accessories
designed to improve reception and audio
quality. A preselector or tuner is intended
to boost signals by tuning the antenna to
match the receiver. Most tuners are passive
which means not powered.
There are also powered antennas which
use active broadband amplifiers to help increase
signals while tuning the antenna to
match the receiver. Active antennas work
best in places where it’s impossible to have
an outdoor antenna, but shouldn’t be thought
of as equal to an external long wire.
Noise filters have long been used to aid
in shortwave listening regardless of the type
or size of antenna. Many high-end receivers
have noise filters built-in, and manipulating
them can reduce adjacent channel interference
or other noises which make listening
less enjoyable. If your receiver doesn’t have
such a filter, you can add an out-board filter
which will be very
effective.
The best filters
use digital signal
processing (DSP)
and are very effective
at removing
interference and
making otherwise
unreadable signals
ICOM SP-23 Noise Reducing
Speaker. Passive
external speaker allows
you to customize the
audio from your shortwave
receiver. (Courtesy:
Icom)
listenable. They are
particularly good
at removing static,
ignition, pulse and
power line noise.
DSP filters are
powered and are
more expensive