Ten-Tec RX-320 -- JUN 03
adio technology has steadily changed
over the decades. From tubes and
hand-wired tag strips at the start,
we’ve moved to transistors mounted on printed
circuit boards, then on to today’s mix of compact integrated circuits (ICs) and Surface Mount
Devices (SMDs). We’re a long way from the
heyday of solid, squat Collins, Hammarlund and
Eddystone radios with their gently glowing
tubes, analog (or mechanical-digital) dials and
polished knobs.
One of the newer kids to show up on the
radio block in the last decade and a half is the
technique of digital signal processing (DSP) –
using ICs (really, special purpose computers on
a chip) that take a radio signal, digitize it, and
then manipulate the digitized radio signal according to whatever the software instructions tell it
to do. What used to be done in analog mode with
crystal filters or networks of inductors and capacitors, can now be achieved by a chip or two
and some software.
Of some significance is the fact that software tells the hardware what to do: Tell a chip
(via software) to think that it’s a 1.8 kHz SSB
filter and it will. Change the software, tell the
filter it’s now a 6 kHz AM filter, and it behaves
accordingly. This will eventually lead in the next
decade or so to radios that will change their abilities completely with a push of a button.
In the meantime, we’re seeing DSP processing show up in a number of our radio toys,
and the manufacturers of said toys are also realizing that computers make very nice “radio control panels.”
Okay, a riddle for all you shortwave enthusiasts out there – what is black
and rectangular? Smaller than a
breadbox? Is deserving of great
fame? Has more faces than a
Louisiana Congressman confronted by PAC money, yet
(unlike the Congresscritter)
gives good value for money to
the public?
If you said “RX-320” then
I’m already preaching to the
choir. If, on the other hand, you
said “Hunh?” or “RX-320 –
isn’t that something for
Athlete’s foot?” then you
should read on…
❖ Ten-Tec’s Tricky
Black Box
Ten-Tec RX-320
By Lee Reynolds
Tennessee, is known to radio buffs for
their ability making military, commercial
and amateur-grade radios using DSP techniques. They’ve extended that knowledge
and manufacturing capability into pricing territory formerly occupied only by
the higher end, portable, analog, shortwave radios and have produced the RX320 – a compact ‘black box’ radio that
has no knobs, no lights and only a power
switch and a few connectors on the back
panel. Sounds plain? You betcha it
does…until you combine it with the PC
that it was designed to operate with. All
of a sudden it turns into a PC/radio hybrid that offers the best of both worlds.
Let me explain further –
The RX-320 is designed to be a
shortwave receiver covering 100kHz to
30MHz, AM, LSB, USB and CW. Instead of having a regular control panel, it
has a serial connection for a PC to talk to,
and control software that is run upon that
PC. Sensitivity figures are good at about
.3uv for 10dB S/N ratio; stability is more
than sufficient to handle today’s digital
modes; and the radio offers up to 34 IF bandwidths.
When you order the RX-320 you receive
the unassuming black box itself, a wall transformer to power it (15 VDC), a telescopic whip
antenna that screws into the top of the radio
(you can use an external antenna as well), the
interface software, a male to female DB9
straight-through cable to connect the radio to
your PC, a 30 page manual, and an audio patch
There’s a lot of power hiding in this little black box... power
unleasher when you make the connection between the rear of the
Ten-Tec in Sevierville, RX-320 and your computer.
June 2003
cable to route the ‘320’s audio into your PC’s
sound card, headphones or an external speaker
(if you choose not to play the ‘320 back through
your system’s speakers).
❖ Installation
Plug in the wall transformer, connect the
serial cable between the PC and the ‘320, connect the antenna or screw in the whip and, for
simplicity’s sake, connect a speaker or headphones to the External Speaker jack on the back
of the radio. Pop the 3-1/2 inch floppy into the
PC, run setup, start the program, set the COM
port and you’re up and running! If your PC
doesn’t have a floppy you can download the
interface software from the ‘net.
Usually the business end of a radio is the
front panel; in the case of the RX-320 it’s the
rear panel.
❖ Interface
The manufacturer-supplied software is
quite reasonable in terms of quality, features,
and performance; it’s excellent for getting your
toes wet with this rig before you go on to choose
the software that really makes your boat float!
Not too simple, not too fancy, it won’t scare the
neophyte and it won’t disgust the experienced
listener. The interface offers a virtual front panel
display for the radio that resembles a real Ten-
Tec box and offers many of the controls you’d
expect to find on a physical radio.
as you like that will work interactively with
the ‘320.
❖ What’s inside
Where things start to get interesting is when
you check out the ‘Spectrum’ and ‘Memories’
options –
Ten-Tec did a nice job of designing the
radio and managed to achieve a good balance
between cost of manufacture, price and performance. Like many modern radios (later
than, say, 1996 or so), when you crack the lid
and take a look inside you are struck by the
Spartan appearance of the boards. (You suffer the same effect, only far worse, when you
look inside the high-end Watkins-Johnson HF1000 or the Ten-Tec RX340, because they
are equally spare-looking but cost about
$4,000 each!)
❖ How well does it work?
‘Spectrum’ (above) is a dandy little application that will quickly mute the radio, sweep it
across a user-selected portion of the radio spectrum and plot the results in graph form. Here I
chose the local AM band as an example. You can
see just where the activity is and clicking on a
peak with your mouse tunes the radio to that
“Memories” is the control for a nice,
simple frequency database you can configure
RF board
I’d say that it does extremely well overall; the price/performance ratio is extremely
good. It’s an excellent SWBC radio and with
the stronger broadcasters you can open up
the bandwidth to improve fidelity to equal or
exceed that of your car radio on AM. It does
very nicely on sideband, stability is excellent, and the wide selection of IF filters helps
winkle stuff out of the mush.
Most useful of all, it’s also very capable
as a receiver for digital utility transmissions
as well. This radio combined with your PC’s
sound card makes for a very nice starter station for ALE, HFDL, RTTY, PSK31 and
SITOR decoding – I’d have happily assassinated any given individual for this kind of
capability at this price just fifteen years ago.
I tested the ‘320 against an ICOM R-75,
both radios being fed from a Stridsberg HF
multicoupler; anything the R-75 could hear
was equally listenable on the ‘320. This is a
$300 radio that acquits itself creditably against
devices costing much more.
The only negative observation I have to
make against this radio is that sensitivity below about 1.2MHz drops off fairly quickly.
This is a combination of two things – deliber-
DSP Board
ate design to prevent troubles with overload
– and minor miscalculation – it dropped off
more than was anticipated. Modifications to
correct this do exist and information is available on the Internet on how to perform them.
Users who have performed these modifications have stated that the radio goes on to
perform very well across its entire frequency
span as a result.
Pros –
Very good performance/cost ratio
Extremely flexible due to wide range of interface software availability
No image problems (normally a bugbear of
radios in this price range)
34 IF bandwidth filters from 300 kHz to 8
kHz are available to the user
Tuning steps down to 1Hz available (again,
not normally available in this price class)
Cons –
No RF attenuator available
No RF gain control
Sensitivity drops off drastically below 1.2 MHz
Comparatively slow 1200 Baud serial interface
But wait! There’s more! (As they say…)
❖ Two interesting late
First of all, the basic RX-320 has been
established as being easily modifiable to provide the 12kHz IF output required for DRM
reception (DRM is a digital audio transmission mode that bids fair to become the transmission standard of the future on shortwave)!
I’ve tested this myself – it’s easy and it works
– all you need once the mod is done is the
DRM decoding software, which is available
in both commercial and shareware versions.
Secondly, I think Ten-Tec must have been
spying on the listener/hacker community; a
new model replacing the RX-320 – the RX320D – has been announced that already has
the DRM modification incorporated into it
plus the RF front end
has been modified to fix
the lack of sensitivity
at the lower frequencies.
In summing up, this
is an excellent radio at
a great price ($300)
with a large amount of
third-party front-end
software available for it
that effectively turns it
into many different radios (see following
page). Not only does it
cover the shortwave
bands well, it can now
also keep your listening up to date by handing you the ability to
receive DRM signal on
a platter! What’s not to
like? I just wish I had a
few more of ‘em in the
June 2003
Software for the RX320
By Lee Reynolds
ou may have read the foregoing observations on the basic, out of the
box Ten-Tec RX-320. Now I’ll
cover the aspect of owning such a radio that’s
the real fun – all the different front end control packages you can get for the device.
That’s the way you interact with your radio,
and (unlike a traditional radio) if you don’t
like the ergonomics of your rig’s software you
can just drop in another front panel and set
of abilities to replace the disliked one!
Some packages suit the needs of program listeners, others are aligned more with
the interests of utility fans; one or two even
serve the listener who wants to put his radio
onto the Internet! A lot of software is available for this radio, so let’s get down to it. I’ll
be assessing programs for the Windows 98
(or better) environment only this time around,
but I know there are a least a few pieces of
software out there for running the ‘320 with
a Mac or LINUX box.
❖ Freeware Programs
GNRX320 is a nice piece of code that
was written by Gerd Niephaus. It’s stable,
easy to install and is light on system resource
use, so you’ll easily be able to run it on that
old Pentium 200 system you have in the basement. The front panel layout (below) is clean
and intuitive, although lacking any on-screen
simulation of a tuning knob (mouse wheel frequency tuning has been added with version
1.30, though!). Access to all available filters,
tuning steps and other RX-320 functions is
provided. Gerd also added an implementation of passband tuning that can be quite useful. This program has two useful add-on programs that make it of interest to both the
program and utility listener –
GNPDB – a database for displaying and
manipulating the ILGRadio broadcast database. It can be used in standalone mode if
you so desire, but if used with GNRX320 it
can be used to look up the frequency that the
RX-320 is tuned to or it can tune the RX-320
to frequencies of interest you are finding in
the database.
GNKFDB - uses the Klingenfuss “Super Frequency List” database (this one’s good
for utility listeners!). It works in a similar
way to GNPDB but is limited to tuning the
radio to the result of searches in the K’fuss
database – you can’t get the database to look
up a frequency you’ve just set the ‘320 to.
All in all, solid, easy to use, and the add84
June 2003
on programs make it a very useful program
for the general-purpose listener.
RX320 is, again, a nicely done piece of
code. A ‘320 enthusiast by the name of Clifton
Turner wrote it but he hasn’t produced any
updates for it in a while, maintaining that the
final version(s) have been released. Installation is simple. All ‘320 features are available
and the software adds a few more that the
‘320 alone cannot provide, such as a tuning
scheduler, passband tuning, bandscope, a
miniature controller that occupies minimal
screen real estate, easy to program memory
buttons, automatic filter selection by mode
and programmable data mode (FAX, RTTY,
etc.) frequency offsets. Again, there’s a useful ancillary program available –
DB320 – an interactive ILGRadio database for use with RX320. Again, crafted to
work with its companion ‘320 program, the
database will automatically look up the frequencies you tune your ‘320 to or tune the
‘320 to frequencies you look up in the database.
This program works well and presents
an appearance that’s more radio-like than the
one shown by RX320. You may find it more
familiar and usable as a result. A good workhorse for the program listener.
cies. The basic ‘320 hardware has no built-in
ability to perform scanning itself, but this
program adds LF/HF scanning as well as anything in the consumer-grade market can.
Squelch-based scanning isn’t implemented in
this package, but five different modes of scanning are available – memory, band, limit, continuous and file scanning (where the file can
be a file created by the RX320 program above!)
Again, the “front panel” model owes more
to Windows than to physical receiver design.
Additional features include fully programmable tuning/recording (and scheduling
thereof), dual range S-meter, dual VFOs, 24
direct access filters, passband tuning and 160
scratchpad memory positions. There’s also
a nice add-on or two –
SCAN320DB – once again, an interactive database access tool that works with
SCAN320. This particular database front end
is a little different in that it possesses a receiver mini-control panel that it displays along
its top edge. You can minimize SCAN320 and
run all operations entirely from the database
viewer itself.
B-LOG – is an integrated logging utility
that works nicely with the other two components. If you’ve been looking for a logger but
didn’t want to spend too much money, the
price for this one can’t be beaten.
This program is definitely one for the
utility listener who wants to monitor a number of frequencies for activity.
❖ Commercial Offerings
SCAN320 – written by Tom Lackamp,
SCAN320 was created (as the name suggests)
to address the needs of those who want to be
able to scan a number of different frequen-
First up is ERGO 4.0 – from Creative
Express (http://www.swldx.com). ERGO is
a very interesting approach to computer-radio integration that was designed with the
program listener in mind, I think. This program can provide a simple receiver control
panel for a number of different radios along
with built-in interfaces to the ILGRadio database, HFCC database, Fineware SWBC files
and Whamlog database. All these databases
make for a very comprehensive index of what’s
on when and where on the bands, and via
which transmitter sites.
ERGO also has some very useful builtin propagation tools that access Internet data
sources for up to the minute forecasts which
are then used to give you nicely integrated
visual displays of signal paths between two
points and the usable frequencies between
those points. Good stuff if you’re trying to
get that elusive signal from Nibi-Nibi and
need to know when your best chance of hearing it will be. Add in the ability to process
received audio using the DSP abilities of your
sound card, linking audio clips to database
and logger entries, and receiver control via a
local network or the Internet – you’ve got
something that’s definitely worth a much
closer look.
This package is for the hardcore SW
broadcast band DXer – with the full complement of databases and its real-time propagation forecasting abilities, it’ll tell you when
and where you should be listening for that
elusive DX target! It also supports a number
of radios other than the RX-320.
N4PY – is the brainchild of N4PY, Carl
Moreschi (http://www.ralabs.com/n4py/)
who produces control software for the TenTec range. If you’ve grown used to the software that Ten-Tec provided with the RX-320
you’ll find that this package bears a fairly
close resemblance to it in certain ways. This
product will run under Windows 3.1 - unlike
any of the others – and displays modest system requirements. Passband tuning is implemented, one touch selection of a band is useful and a bandscope is implemented. This is a
“fewer frills” package but is quite workmanlike in its attitude to getting the job done. If
you own a Ten-Tec Pegasus then this software can run the Pegasus as the host radio
and use the RX-320 as a client that will follow tuning changes on the Pegasus. No integration/link with the ILGRadio database ex-
If you want more than the basic Ten-Tec
software can offer but you aren’t looking for
a replacement with a steep learning curve,
then this package may be of interest to you.
SCOPESTATION 3.00.08 – comes from
CallSign Software (http://www.callsign
software.com) and is a member of a range of
products made for the Ten-Tec Pegasus, Jupiter, RX-350 and RX-320. This beast has a
radio amateur heritage (as you can tell by looking at the design of the front panel) and a
feature that makes it particularly well suited
to the SWL who has an interest in the ham
bands (as well as SW in general). All typical
functions are supported well with some additional capabilities that are very welcome.
Support of the ILGRadio database is provided – interestingly, so is support for the
HamCall radio amateur CD database.
The S-meter is extremely tweakable (so
much so that I defy anyone to say that it can
operate in a way that they don’t like, once
they’re done setting it up to their taste), and
a very thorough frequency calibration procedure is available for making sure that your
‘320 is absolutely spot on at all times.
CallSign has also performed a number of
neat tricks with band sweeping and signal
sampling – you have the conventional frequency sweep and display with the ability to
click on interesting looking peaks to tune to a
given frequency, more unusually you also
have a signal sampling mode that allows you
to take a close look a the waveform of any
signal you’re listening to. (I understand that
some users are simply fascinated by this
trick!) Another good touch is that have having the software automatically set a zero
baseline for signals when using the ‘scope
helps compensate for unusual noise levels,
etc. ADIF file format support is included as
well; this enables you to import data from a
number of amateur and SWL related programs.
This is a good package for the guy who
likes to get into to the nuts and bolts of things
and who likes to heavily customize the way
the virtual ‘front panel’ works. A tinkerer’s
like it a great deal; it offers features that I
haven’t been able to find anywhere else, but
I’d have been reviewing a copy of something
that is no longer current. 3.1 promises some
remarkable band scanning and multi-radio
management capabilities – I’ll report on this
one at a later time, editor permitting!
Okay, that’s a quick take on what’s out
there for the RX-320 aficionado. Additional
packages do exist but space does not permit
me to include them all. You might try a web
search for –
Privalov/Control Panel
RX320/PDA (Yes, software exists that runs
on your Palm Pilot!)
DXRadar (Not, strictly speaking, a control
package, but it performs a fascinating
I’ve used all of the above programs and
own all but one of the commercial ones.
Choosing between them can be difficult, because almost all offer something that, to me,
qualifies as a “killer app”! Do some judicious
research, kick the tires on a few of these programs and form your own conclusions, but,
most importantly, have fun doing so! I did.
This is your equipment
page. Monitoring Times
pays for projects, reviews,
radio theory and hardware
topics. Contact Rachel
Baughn, 7540 Hwy 64 West,
Brasstown, NC 28902;
Visit MT’s website at:
WORLDSTATION 3.1 – produced by
DXtra, Inc. (http://www.dxtra.com) this is
one package that I would very much liked to
have included in this overview but the transition from WS2.0 to WS3.1 occurred at just
the right time to prevent me from being able
to review the newest version. I own 2.0 and
June 2003
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