Key Measurements
Summary
product review
123
FlexRadio Systems FLEX-5000A
HF/50 MHz Transceiver
123
70
140
20
2
20 kHz Blocking Gain Compression (dB)
123
123
70
140
2 kHz Blocking Gain Compression (dB)
94
I3
99
50
110
20
20 kHz 3rd-Order Dynamic Range (dB)
I3
99
50
110
2
2 kHz 3rd-Order Dynamic Range (dB)
33
I3
20
39†
-40
+35
20 kHz 3rd-Order Intercept (dBm)
I3
39†
-40
+30
2
Reviewed by Rick Lindquist, WW3DE
NCJ Managing Editor
defined ham radio bar another notch.
2 kHz 3rd-Order Intercept (dBm)
ExpandingYour Vocabulary
As we said in May 1998 QST when
reviewing the first commercially available
I3
Just as hams once fretted about grid drive,
strictly computer controlled Amateur Radio overmodulation and key clicks, the very na-
transceiver, the Kachina 505DSP: “The ture of SDRs has given rise to a new crop of
relegation of functionality from hardware to issues with names like “latency” and “sam-
software and firmware opens broad vistas of pling rate.” This is serious technology, and
future capability.” Are we there yet? Or did it’s not necessarily for the faint of heart.
-34
TX
-20
-20
-35
Transmit 3rd-Order IMD (dB)
I9
-54
our flight to nirvana get canceled? A decade
In an SDR, analog RF signals are con-
TX
-70
down the road, Kachina is kaput in the ama- verted to a digital bit stream, and everything
teur market, and the newer software defined happens at that level using digital signal
radio (SDR) technology remains far from processing (DSP) techniques before conver-
ubiquitous in the modern ham shack. FlexRa- sion back to analog. As FlexRadio explains,
dio Systems now represents the vanguard of its SDR is “essentially a direct-conversion
equipment manufacturers prodding the Ama- receiver, but the mixing of the LO [local os-
Transmit 9th-order IMD (dB)
pr032
Key: † Off Scale
80 M
20 M
Dynamic range and intercept
values with preamp off.
Intercept values were determined
using -97 dBm reference
teur Radio community into the SDR era.
cillator] to create a 9 kHz IF makes it appear
Let’s face it: Most equipment in today’s a lot like a dual-conversion receiver.” Some-
ham stations reflects only incremental im- thing called a quadrature sampling detector
provements in well-established wireless tech- (QSD) — 0°, 90°, 180° and 270° — is at the
nology, form factor and human user interface. heart of all FLEX models. This generates the
Additionally a “knob mentality” persists, “I” in-phase composite and “Q” quadrature
despite Kachina’s confidence, expressed 10 signals. Are your eyes glazing over yet?
Bottom Line
The FLEX-5000A builds on the suc-
cess of the SDR-1000, retaining the
top-shelf radio performance and adding
features. The package is far less compli-
cated, shedding the many wires, cables,
boxes and connectors that characterized
the SDR-1000. Be prepared to experiment
with the software and settings to get the
most from this radio, however.
years ago, that owners of its milestone radio
FlexRadio points out that direct-
would embrace mouse-and-keyboard operating conversion receivers like the SDR-1000
to the extent that knobs would become “super- and FLEX-5000A don’t require band-pass
fluous.” In 2005 FlexRadio Systems nudged or roofing filters. Because the QSD doesn’t
things off the dime again with its SDR-1000. respond to signals below its passband but is
The FLEX-5000A raises the software- susceptible to odd harmonics above its LO
Mark J. Wilson, K1RO
Product Review Editor
From July 2008 QST © ARRL
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QS0807-PR01
Manufacturer’s Specifications
Measured in the ARRL Lab
FM adjacent channel rejection: Not specified.
20 kHz offset, preamp on:
29 MHz, 59 dB; 52 MHz, 44 dB.
FM two-tone, third-order IMD dynamic range:
Not specified.
20 kHz offset, preamp on:
29 MHz, 59 dB*; 52 MHz, 44 dB*;
10 MHz offset: 52 MHz, n/a.3
S-meter sensitivity: Not specified.
Squelch sensitivity: Not specified.
S9 signal at 14.2 MHz: preamp off,
50 µV; preamp on, 50 µV.
At threshold, preamp on: SSB, 14 MHz,
0.28 µV; FM, 29 MHz, 0.22 µV;
52 MHz, 0.6 µV.
As specified.4
0
0.02
0.04
0.06
0.08
0.1
Figure 1 — CW keying waveform for
the FLEX-5000A showing the first two
dits in full-break-in (QSK) mode using
Audio output power: 10 dBV at 600 Ω.
IF/audio response: Not specified.
Range at –6 dB points, (bandwidth):
CW (500 Hz): 345-856 Hz (511 Hz),**
Equivalent Rectangular BW: 499 Hz;
USB: 141-2851 Hz (2710 Hz);
LSB: 140-2850 Hz (2710 Hz);
AM: 71-3293 Hz (3222 Hz).
First IF rejection, 43 dB5; image
rejection, 88 dB.
external keying. Equivalent keying speed
is 60 WPM.The upper trace is the actual
key closure; the lower trace is the RF
envelope. (Note that the first key closure
starts at the left edge of the figure.)
Horizontal divisions are 10 ms.The
transceiver was being operated at 100 W
output on the 14 MHz band.
Image rejection: 70 dB.
Transmitter
Transmitter Dynamic Testing
Power output: HF and 50 MHz: SSB, CW,
FM, 100 W (high); AM, 25 W (carrier)
HF: CW, SSB, FM, typically 100 W high,
<1 W low; AM, typ. 25 W high, <1 W low;
50 MHz: CW, SSB, FM, typ 99 W high,
<1 W low; AM, typ. 25 W high, <1 W low.
QS0807-PR02
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
Spurious and harmonic suppression:
HF, >55 dB; VHF, >65 dB
HF, 51 dB; VHF, 61 dB.
Meets FCC requirements.
SSB carrier suppression: >55 dB.
HF, 51 dB; VHF, 54 dB.
HF, 61 dB; VHF, 60 dB.
Undesired sideband suppression: >55 dB.
Third-order intermodulation distortion (IMD)
products: –33 dB PEP at 100 W on 14 MHz.
3rd/5th/7th/9th order (worst case band):
HF, –34/–40/–48/–54 dB PEP;
VHF, –21/–32/–39/–40 dB PEP.
CW keyer speed range: Not specified.
CW keying characteristics: Not specified.
1 to 60 WPM.
See Figures 1 and 2.
29 ms.6
f -4
f -2
f
f +2
f +4
c
c
c
c
c
kHz
Transmit-receive turn-around time (PTT release
to 50% audio output): Not specified.
Figure 2 — Spectral display of the FLEX-
5000A transmitter during keying sideband
testing. Equivalent keying speed is
60 WPM using external keying. Spectrum
analyzer resolution bandwidth is 10 Hz,
and the sweep time is 30 seconds.The
transmitter was being operated at 100 W
PEP output on the 14 MHz band, and this
plot shows the transmitter output 5 kHz
from the carrier.
Receive-transmit turn-around time (tx delay):
Not specified.
25 ms.6
Composite transmitted noise: Not specified.
See Figure 3.
Size (height, width, depth): 9 × 9.3 × 12.4 inches; weight, 13 pounds.
Price: FLEX-5000A, $2799; antenna tuner option, $299; RX2 second receiver, $649.
*Measurement was noise-limited at the value indicated.
**Varies with CW pitch setting.
1The level indicated is where the sound card’s ADC went into overload. Gain compression
could not be measured because of this behavior.
2An input level of 0 dBm was higher than the ADC overload level, so the test was not performed.
3No IMD product could be detected.
4Audio output is dependent on external amplified speakers.
5Spur near the IF frequency. Note: The IF is in the audio range, so IF rejection will not
affect RF performance.
QS0807-PR03
0
6Measurements made with 1.6 GHz dual-core processor. Turnaround time may be faster with
higher speed CPU.
-20
-40
-60
-80
-100
-120
-140
-160
-180
package that’s free of the surfeit of wires,
cables, boxes and connectors that character-
ized the SDR-1000. (Further eliminating the
need for wires is VAC [virtual audio cable],
third-party software that routes signals for
digital programs to and from the FLEX-
5000A.) As one “Flexer” remarked on the
FLEX-5000A Web site, “fit and finish are
light years ahead of the SDR-1000” and “it
looks like a professional radio.”
really counts. The current maximum sampling
rate (more on this topic later) permits viewing
192 kHz of band spectrum, with immediate
access to both VFOs as well as to the panoply
of major functions, most common, some less
so. You access most functions via buttons,
sliders, menus and sub-menus or tabs.
102
103
104
105
106
Figure 3 — Spectral display of the
FLEX-5000A transmitter output during
composite-noise testing. Power output is
100 W on the 14 MHz band.The carrier, off
the left edge of the plot, is not shown.This
plot shows composite transmitted noise
100 Hz to 1 MHz from the carrier.
“LightYears Ahead”
What the FLEX-5000A brings to the table
now is a far less complicated Amateur Radio
This ham radio system essentially consists
From July 2008 QST © ARRL
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of the FLEX-5000A box and the PC. It of-
fers 100 W (PEP) on all bands 160 through
6 meters, general-coverage receive (0.01-
65 MHz, same as the SDR-1000) and lots and
lots of features, including several that weren’t
available on the SDR-1000. For example, the
newer model offers substantial improvement
in CW operation, VOX capability and other
novel and useful amenities, plus some impres-
sive performance statistics (see Table 1).
The close-in two-tone third-order IMD
dynamic range of the FLEX-5000A remains
comparable with that of the SDR-1000 and
of some of the best transceivers on the mar-
ket. On the SDR-1000, the best IMD DR
on 14 MHz at 2 kHz spacing was 99 dB at
the medium preamp setting, but as much as
10 dB worse at other preamp settings. On the
FLEX-5000A we measured 99 dB on 14 MHz
at all spacings, with or without the preamp.
The FLEX-5000A includes some features
that became viable simply because today’s
average PC is a lot more powerful than the
ones common in 2005. By the same token,
continued upward mobility of PC technology
is bound to further improve the FLEX-5000A
down the road, so enhanced performance and
additional features remain moving targets. In
addition, faster video cards can improve radio
performance by offloading of the CPU.
Switching computers Midstream
The “right” computer is key to satisfactory operation of the FLEX-5000A. We
started out with a high-end HP/Compaq dc7700p, which has an Intel E6300 Core
2 Duo processor (2 MB of L2 cache, 1066 MHz bus) running at 1.8 GHz. It was
equipped with 2 GB of memory, a RAID hard drive system and Windows XP Pro.
After we noted performance that was at odds with FlexRadio’s experience, the
manufacturer suggested that we try a Compaq Presario SR5310F with an Intel
Pentium E2140 Dual-Core processor (1 MB of L2 cache, 800 MHz bus) running at
1.6 GHz. This inexpensive machine came with 1 GB of memory and the Vista Home
Premium operating system. ARRL installed a FireWire card and removed the fancy
video card and all unnecessary applications that might bog down the processor.
Switching to the SR5310F demonstrated that you don’t need a blazing-hot,
high-end computer to run a FLEX-5000A. On the other hand, there were occa-
sions when it seemed that more computer muscle would have resolved some of
the issues we encountered. The FLEX-5000C model has a built-in Intel Core 2
Duo processor computer with 1 GB of RAM and XP Pro. — Rick Lindquist, N1RL
tion functions needed to run the specific
hardware. The FLEX-5000A has a device
driver just like any other PC peripheral. The
user must enter both the desired sampling
rate and buffer size into the driver dialog
box — which sets up the FireWire connection
parameters and something called “operating
mode” — as well as in the PowerSDR Setup
menu (or “form,” as FlexRadio calls them).
Our unit had the optional automatic antenna
tuner (ATU) installed. It can produce a rather
disconcerting symphony of grinding and whir-
Pegasus or SDR-1000 — or, for that matter,
ever controlled a conventional transceiver via
computer or Internet — appreciates that the
most significant part of the learning curve
is getting used to mousing rather than tried-
and-true dial twisting and button pushing.
FlexRadio’s slogan is “Real radios don’t
need knobs!”
Mouse control is an acquired taste. Think
of it this way: The front panel of the FLEX-
5000A is the graphical user interface of a
computer program, and, for better or worse,
FlexRadio got rid of the gaggle of wires
that shackled the SDR-1000 and its associ-
ated high-end sound card by using a FireWire
(IEEE-1394) interface to handle signals
between the black box and the PC. Hurry ex-
plained that several essential “threads” travel
up and down the FireWire cable, including
receive and transmit I and Q signals (essen-
tially the radio’s IF) and receive and transmit
audio. The FireWire cable may be up to 10
feet long.
ring as it tries to come to terms with whatever the mouse has become the de facto control-
load you have attached to one of the three ler for programs ranging from accounting to
SO-239 connectors on the box’s rear apron word processing. Last time I was in a Best
Buy store, the array of computer mice and
adjunct control devices was astonishing.
The FLEX-5000A’s tuning controls en-
able all the usual capabilities you’d expect
on a conventional Amateur Radio transceiver
and more. You can set (or reset) the tuning
step anywhere from 1 Hz to 10 MHz with a
mouse click, lock the VFO, operate “split,”
dump the contents of one VFO into the other,
equalize VFOs and listen to two frequencies
at the same time with the click of a button.
One disappointment was the minimal
“scratch memory,” a feature I’ve always
found extremely handy in contests. Clicking
SAVE retains a frequency, mode and filter,
but only for a single frequency. Some adept
programming that already may be on the
drawing board very likely could overcome
this minor deficiency.
(Figure 4). The ATU has semi-automatic and
automatic settings as well as memory capabil-
ity. You can set the maximum SWR threshold
(up to 3:1). Unless you have the ATU tab open
on your screen, however, you may not know
right away if the tuner couldn’t find a match.
Although a tuner fault will not necessarily
switch the ATU to bypass mode, a red HIGH
SWR warning will flash when you transmit.
The FLEX-5000A’s transmit and receive
signal paths are completely independent,
opening new horizons of opportunity.
For example, at press time
The “functional equivalent” of the SDR-
1000’s sound card and USB control now
resides in the FLEX-5000’s hardware. These
include low-level control and communica-
an optional full-featured
second receiver, known
as RX2, was poised to
provide the potential for
SO2R — single-operator,
two radio capability — in
The FLEX-5000A gives you a num-
ber of ways to tune. On the panadapter
display — the one you’re likely to use the
most — the radio lets you put a signal in
its crosshairs. Then click, you’re there,
aside from a little fine tuning (FlexRadio
calls this “ClickTune”). You can do the
same thing with the waterfall display. It’s
possible to choose a split panadapter/waterfall
or any combination of the two, as shown in
Figure 5. At the PowerSDR window’s normal
size, the menu to access this feature may not
be visible. It’s below the main console win-
a single box.
Knobs? We Don’t
Need No Stinkin’
Knobs!
Anyone who’s ever
used a Kachina, Ten-Tec
Figure 4 — Rear view
of the Flex-5000A.
Note the real analog
connectors here.
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Figure 5 —You can split the PowerSDR screen to show any
combination of the panadapter and waterfall displays.
Figure 6 — PowerSDR offers 3 or 10 band graphic equalizers for
both receive and transmit.
dow and seemed tacked on as an afterthought
(or maybe they just ran out of space). I liked
the combination panadapter/waterfall display,
since the waterfall sometimes shows signals
not readily visible on the spectrum scope.
Manually tuning with the cursor works
like this: Hold down the left button and the
cursor becomes a little hand. Then swipe the
“hand” across the display horizontally in the
desired direction. But there’s the rub. I had
to swipe in the opposite direction, or sense,
from what my aging brain expected. To move
up the band, you swipe from right to left,
whereas on a conventional transceiver you’d
turn the knob from left to right (clockwise).
It’s logical when you think about it (mov-
ing from a lower frequency to the left to a
higher one to the right), and I eventually got
the hang of it.
control knobs that you can set up for VFO tun- especially when you’re working in one of the
ing, RIT, filter width, mode and other often- menus, enabling other radio features such as
used functions. The optional Griffin Power MULTIRX or using (not just running) another
Mate VFO control knob is also available if program on the same PC. Lowering the RX
you find you can’t live without a knob.
buffer seemed to cure this. I went through
2048 to 1024, experiencing far less dropout
at the latter and even lower settings.
Of Buffers and Sampling Rates
The various buffer and sampling rate
There’s a tradeoff, however. Reducing the
settings significantly affect how — and how size of the RX buffer alters the filters’ skirt
well — the FLEX-5000A functions. Reach- shape and makes them less effective — “roll-
ing equilibrium can be a chore. First you need off” filters as opposed to “brick-wall” filters.
to set the sampling rate and buffer size for With a too small buffer you’ll find essentially
the FLEX-5000A driver, which determines no change in the actual passband below a
the data rate and buffer size for the FlexWire certain filter selection, depending on mode.
interface. Once inside PowerSDR, you enter On the other hand, latency — a minute but
the same sampling rate and buffer size under finite lag between the time you key the PTT
the Setup menu AUDIO tab and set buffers for and the RF signal appears — gets closer to
transmit (TX) and receive (RX) under the real time with smaller driver and audio tab
DSP tab. These DSP buffer settings signifi- buffer sizes; the DSP TX buffer also has
If you don’t like swiping/sliding to tune,
the little mouse scroll wheel does the job
quite nicely. This made better sense to my
brain too. You scroll up to move up in fre-
quency, down to move down.
cantly impact filter shaping and latency.
FlexRadio suggests setting the driver and for a particular mode can be a juggling act.
the audio buffers as low as the associated
computer’s processor can handle (lower buf-
fer settings shift the workload to the proces-
an effect, however. In short, getting it just right
Big and Beautiful SSB
Simply put, this radio can generate a
You can use the cursor not only to tune
but to shift the receive passband and change
its bandwidth. FlexRadio calls this feature
“FilterSlide.” It works very well for custom
filtering on the fly, although the preset filters
suffice under most circumstances. Filters are
not mode-specific and you can winnow the
passband down to a lean 25 Hz assuming
adequate sampling rate and buffers. You can
click and drag the VFO B passband anywhere
on the visible display — above or below your
operating frequency.
PowerSDR also lets you control vari-
ous radio functions, including tuning, band
switching, mode, filter and RIT/XIT via the
keyboard. This includes the ability to directly
enter a frequency.
sor with less latency or delay but broader remarkable SSB signal. Within legal limita-
filter skirts). The “Buffers and Sample Rate” tions your ability to tailor the radio’s audio
appendix of the Owner’s Manual advises characteristics is extensive. The panadapter
avoiding a buffer size of 512 for SSB opera- displays your SSB/phone waveform, so you
tion “except for casual QSOs and then only can see what’s going on. The compander —
at sample rates of 48 kHz and 96 kHz.” For something not found on most transceivers —
those situations where you need steep filters, yields bigger, louder audio while not being
however, the manual suggests buffer sizes obnoxious. It is possible to engage both the
of 2048 or 4096. It’s a bit different for CW compressor and the compander, but you’ll
and digital operation. For these FlexRadio want to avoid extreme settings. Less is more
recommends steering clear of buffers of 512 in this case. Stations I worked told me the DX
and 1024 and using “only the sample rate button, which is new with PowerSDR v 1.10.4,
of 48 kHz.” FlexRadio says that some of added another S unit or so to my signal. How
these suggested settings are in error and has cool is that? Switching in my headset’s DX
revised the instructions for proper selection mic element augmented the effect.
of buffer size.
The radio also has a “leveler” — a sort
Operating with our second computer of AGC to compensate for times when the
(see sidebar, “Switching Computers Mid- operator changes position with respect to the
stream”) and using a 192 kHz sampling rate, microphone. A NOISE GATE is available to
the FLEX-5000A was more prone to audio handle high background noise situations; it
dropout — essentially “holes” in the audio — operates independently of VOX.
For less pointing and clicking, an optional
ShuttlePRO controller is available through
FlexRadio. This mouse-like device has 15 pro-
grammable buttons and two concentric tuning/
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The dual equalizers, one for transmit and CW setting seemed to be a buffer setting nals will appear to ‘jump out’ of the noise,”
one for receive, go far above and beyond the of 512 at a 48 kHz sampling rate, although enhancing weak-signal reception. Dropping
“tone controls” of many hardware transceiv- filters are less sharp with a buffer that small. the AGC gain also means less AF output,
ers. Both offer a choice of 3 or 10 bands The latency problems that plagued us on CW hence the interaction. On the other hand,
(see Figure 6). The 3 band EQ unit is great with the SDR-1000 are pretty much gone audio dynamic range improves.
for quickly compensating either transmit or with the FLEX-5000A, however.
Making volume levels more uniform
receive audio; the 10 band unit allows you to The CWX (keyboard/CW memory) menu requires tinkering with the AGC-T and AF
apply additional nuance. You click the MON accesses nine easily programmable CW controls. The manual advises setting the
button to listen to your own audio. Some memories (just type and play!) and keyboard AGC-T control “as low as possible to comfort-
sampling rates and buffer settings we tried capability with a substantial type-ahead ably hear the signal of interest” (the default
imparted varying degrees of latency, lending buffer. I found these especially convenient setting is 90) while setting the AF gain to
an “echo” effect to what you’re hearing.
when using the FLEX-5000A as part of a slightly louder-than-comfortable level.
One station judged the FLEX-5000A’s the W1MGY Titanic anniversary special I’m not sure I ever really found that “sweet
SSB audio quality “orders of magnitude bet- event. Opening the CWX menu immediately spot,” however.
ter” after I spent a few minutes setting up the switches the transceiver to CW mode (and to
10 band equalizer on transmit. Another fellow the last-known CW filter setting).
The separate AGC control lets you set the
AGC action to slow, medium, fast, long or
said I had “a perfect signal.” (When was the
Using the type-ahead buffer involves first custom. You also can turn the AGC off al-
last time you heard that?) I used the 10 band putting the keyboard output on “pause,” then together. It’s possible to customize the AGC
receive equalizer to compensate for low-end activating the keyboard keys to type. To send action via the SETUP menu.
emphasis resulting from the effects of noise what you’ve typed, simply “un-pause” the
Gremlins?
We encountered a few transient gremlins.
reduction, which is excellent by the way.
output stream. It’s possible to continue typ-
I assumed (silly me) that the record ing at that point, assuming you’ve still got
feature was essentially a digital voice keyer. the keyboard activated. My CW preference With the Vista computer, the display driver
Not really. It’s actually designed to record was a combination of the CW memories and would quit momentarily from time to time
snippets of off-the-air audio. It does let the keyboard.
— at one point twice in the course of an
you record your own messages — lots of A separate “Morse Definition Editor” lets hour-long QSO. This typically occurred only
’em — in very high-quality audio. The only users define or redefine nearly each element while using high sampling rates. On numer-
way you can transmit them, however, is by in the 64-character set. Send CW in German a ous occasions I found it necessary to stop
manually keying the PTT line and clicking lot and want to sound like a native? Program and restart PowerSDR after it froze up on the
on the message file; initiating the message in those inflected letters (ü, for example), und first try. Less frequently the radio would not
alone does not trip the VOX! I also didn’t see Du bist ein Berliner!
any way that you could rename the file (the The speed setting on the CWX tab is in- tripping the PTT got it going again.
radio applies a date/time/frequency stamp) to, dependent of the CW SPEED setting on the Other times I’d see this announcement:
say, “CQ contest.” A little digital rejiggering main PowerSDR console. So are the various “Error communicating with the FLEX-5000.
could make this feature more useful. timing/delay settings, which, depending on Please reload PowerSDR to try again.” Start-
receive after the VOX dropped out. Briefly
To retain various audio-related settings your computer, may need a little diddling to ing PowerSDR too soon after energizing the
such as transmit or receive equalization you get just right. You may be able to achieve radio box can cause this, although that was
must save the “transmit profile.” FlexRadio near-QSK on the paddle, but you still have to rarely the case. A further complication: After
includes several stock choices or you can cre- adjust the keyboard settings to get the same clicking “OK” on the error dialog box, the
ate your own. In addition to EQ settings, the effect. Very tight TR delay settings — near program continues to load, then gives you a
transmit profile saves the TX filter high and QSK — introduce annoying pops and clicks second error message informing you that it
low, compander and mic gain settings, lev- in the sidetone. In addition, if you’re listening could not open the driver.
eler parameters, RF output power and ALC on the speakers you’ll also hear lots of relay
values. Very handy! I only wish the radio had chatter from the FLEX-5000A box.
some way of saving various sampling and
While the ATU worked well most of the
time, sometimes it simply balked, and I had
to try again, usually getting a match on a
subsequent attempt. Sometimes I’d get an
A Semi-Automatic AGC?
buffer setting profiles that the operator could
access them with the click of the mouse.
Without judicious use of the AGC-T (AGC error message saying no RF was detected.
threshold) and AF controls, signals can and Other times I got nothing, although the ATU
will block or overload the FLEX-5000A and remained in line, rather than switching to
CW Choices
New with the FLEX-5000A is a real possibly blow your eardrums. FlexRadio bypass as it’s supposed to. Early on, I “lost”
keyer plus provisions for CW keyboard- concedes that users have posed “numerous the ATU function altogether and had to restart
ing, CW memories, dot-to-dash ratio and questions” related to the AGC-T control, everything from scratch a couple of times to
waveform shaping. Even so, CW operation which essentially acts like an RF gain control. get it back.
was a somewhat less enjoyable experience The fact that the AGC-T and AF settings some-
A few times the panadapter disappeared
than SSB. While the manufacturer claims what interact has given rise to considerable or failed to show the spectrum trace. Sam-
the FLEX-5000A is capable of full-break-in explanation in the Owner’s Manual and the pling rate and buffer settings that seemed to
(QSK) CW, most CW aficionados would call online knowledge base.
it “near QSK.” If another station can’t break Here’s the thing: The FLEX-5000A’s sometimes the driver buffer setting would
you with a single dit while you’re sending, AGC, which operates at audio frequencies, change mysteriously and without warn-
it’s not true QSK. seems to be something less than automatic. ing. At least once, the FLEX-5000A quit
work okay initially later didn’t. Then too,
With the first computer, we experienced The AGC-T control adjusts the AGC gain receiving after I’d entered some buffer and
CW latency — that pesky time lag. With the and, as the Owner’s Manual explains, “is sampling rate settings the manufacturer had
delay set at 10 ms, the lowest it goes, sending used to maximize the signal-to-noise ratio suggested. FlexRadio attributes gremlins
was choppy at a 192 kHz sampling rate and based on band conditions (QRN).” FlexRadio like these to Vista and recommends using
a 2048 RX buffer. Operation with the second recommends reducing the AGC gain until Windows XP unless there is a strong reason
computer was much improved. The optimum you reach “a sweet spot at which weak sig- to go with Vista.
From July 2008 QST © ARRL
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Jots and Tittles (in No Particular
Order)
Summer reading List
The nearly 200 page Owner’s Manual
Check out the April and October 2005 QST “Product Review” columns
covering the FLEX-SDR-1000 transceiver, available online at www.arrl.org/
members-only/prodrev/. Those inclined to delve more deeply into this subject
should also visit the award-winning series, “A Software Defined Radio for the
Masses,” by Gerald Youngblood, K5SDR, who’s FlexRadio’s president. These
appear in the July/August and September/October 2002 issues of QEX and are
available on FlexRadio’s Web site. Also, don’t miss “The FLEX-5000A as a Con-
test Radio — A First Look,” by Bill Heinzinger Jr, W9OL, in the May/June 2008
issue of NCJ. — Rick Lindquist, N1RL
(updates available online) is comprehensive,
but the manual and its several supplements
can get highly technical. The book includes
some guidelines to set up the radio for that
first QSO. In addition, FlexRadio’s support
staff and the fraternity of Flexers are willing
to provide ample wise counsel to help you
and your FLEX become fast friends.
If you like using memories, you’ll love
the FLEX-5000A, since you can essentially
store as many as you’d like, limited only by
the available space on your computer’s hard can set up an 8 to 10 kHz passband for great AFSK using upper and lower-sideband
drive. Under a “GRP” choice of AM, FM, audio fidelity. The automatic notch filter modes, DIG-U and DIG-L.
SSB or SSTV (there’s no CW group), you can readily dispatched a slight heterodyne I was
So, Are We ThereYet?
store mode, filter, step size, AGC, call sign, hearing on one signal.
frequency and comments. You can input 95
The two adjustable noise blankers are
This latest FLEX has come a long, long
characters to the comments buffer, but only exceptionally effective, and you can enable way from what we looked at in 2005. But, is
about 50 of them show up upon recall.
NB(1), NB2 or both. NB(1) is the more ag- this the radio for which you would forsake all
The ANTENNA SELECTION tab — as gressive of the two
others? In a word, maybe. Here’s why: The
do some other menus and tabs — offers
Clicking the BIN (binaural) button adds FLEX-5000A requires its owner to engage
“Simple” and “Expert” user levels. At the an entirely new dimension to SSB audio.
in what some might consider an excessive
higher end, you can define not only which
The MULTIRX is great! It’s sort of a dual- amount of tweaking and experimenting to get
antenna to connect but on which band, at watch feature. Just for starters, while operat- it working properly with a given PC (think,
what transmitter power level and even at what ing split you can keep inserting as much audio “high maintenance partner/spouse”).
AGC-T setting.
from your transmit frequency as you prefer to
The FLEX-5000A includes built-in help stay ahead of the competition.
A decision to buy really hinges on
whether you’re up for the challenge of the
test equipment. With the exception of the
For those contemplating remote op- FLEX-5000A. Using and, especially, fine
power/SWR circuitry, the radio can test and eration, say from a deed-restricted home tuning the FLEX-5000A for routine or spe-
calibrate itself. As Youngblood explained, location, the FLEX-5000A may be an ideal cialized multimode operating can demand
“You can push a button and walk away for solution. It’s eminently remotable via the a level of technical knowledge and acumen
20 minutes. When you come back, the radio Internet.
that’s a step above that of the average radio
will have gone through the full factory test/
alignment procedure.”
A rear-apron stereo jack is designed to amateur, even in 2008 — and that’s even
drive powered computer type speakers, not excepting the “Expert Level” settings on
The FLEX-5000A’s MOSFET output included. I’m pretty much a headphones guy, the transceiver’s menu. Perhaps “Flexer”
stage is rated at 100 W continuous duty on but occasionally I’ll switch to the speaker. Steve, K5FR, put it best in his posting to the
all modes. This is a recent change that reflects Do this with the FLEX-5000A while operat- Flex-Radio Web site. “The Flex family of
the results of additional testing, as the manual ing phone, and you’ll also quickly discover radios has brought a new ‘Event Horizon’ to
warns against operating continuous carrier there’s no anti-VOX.
Amateur Radio,” he said. “These are exciting
modes above 40 W output for longer than
Three band-stacking registers retain times to be a ham.”
15 seconds. The radio box appears to have frequency, mode, filter, preamp and other
adequate cooling, although it did get warm important settings.
For the most part, I was able to get our
FLEX-5000A working to my satisfaction
and the fan came on continuously following
moderate exercise during a special event let you zero in on the particular part of the breathtaking, the keyboard and memory
operation on CW.
band you want to see in the display window, implementation is superb and latency issues
The software version we used (v 1.10.4) and they permit some compensation for the were very nearly non-existent. To achieve the
The display ZOOM and PAN controls on CW; the narrow, brick-wall filtering is
included some noise reduction (NR) “en- smaller chunk of spectrum visible at lower same level of satisfaction on SSB did require
hancements.” A few Flexers consider these sampling rates.
reconfiguring the radio with new sampling
a step backward or, as one said, “a work in
The preamp is terrific. It neither raises rate and buffer settings.
progress.” FlexRadio support offered some the noise level nor affects the receiver’s
Many happy Flex campers are enjoying
basic numbers to stick into the NR menu dynamic range. I wondered, however, why their SDR-1000s and FLEX-5000As, and
(for example, how many “filter taps” are it couldn’t just be a button that illuminates I had a great deal of fun using this radio
optimal?).
when enabled, like the ones on many myself, despite — and possibly because
The FLEX-5000A offers a huge variety “hardware” transceivers. What’s there now of — the challenge. With an expanding
of audio and RF connections and a substan- requires selecting “On” or “Off” from a tiny user base and the efforts of the fine folks at
tial switching matrix for accommodating pull-down menu. There is no attenuator.
FlexRadio, I’m confident it will get there in
outboard transverters. This makes it pos-
Very handy is the ability to establish a the relatively near future. Better yet, it will
sible to enjoy the SDR advantage on VHF separate low-power output level for the trans- keep on going!
and UHF.
mitter while the ATU is doing its thing. Once Manufacturer: FlexRadio Systems, 13091
the tuner successfully matched an antenna I Pond Springs Rd, Suite 250, Austin, TX
The FLEX-5000A receiver sounds expected to see 1:1, but it read 0.0:1.
78729; tel 512-535-5266; www.flex-radio.
For digital modes, the radio employs com.
The 0 BEAT button works fine on CW.
excellent on the AM broadcast band. You
From July 2008 QST © ARRL
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