Compaq FLEX-5000A - Manual (Page 6)

From July 2008 QST © ARRL
The dual equalizers, one for transmit and
one for receive, go far above and beyond the
“tone controls” of many hardware transceiv-
ers. Both offer a choice of 3 or 10 bands
(see Figure 6). The 3 band EQ unit is great
for quickly compensating either transmit or
receive audio; the 10 band unit allows you to
apply additional nuance. You click the
MON
button to listen to your own audio. Some
sampling rates and buffer settings we tried
imparted varying degrees of latency, lending
an “echo” effect to what you’re hearing.
One station judged the FLEX-5000A’s
SSB audio quality “orders of magnitude bet-
ter” after I spent a few minutes setting up the
10 band equalizer on transmit. Another fellow
said I had “a perfect signal.” (When was the
last time you heard that?) I used the 10 band
receive equalizer to compensate for low-end
emphasis resulting from the effects of noise
reduction, which is excellent by the way.
I assumed (silly me) that the record
feature was essentially a digital voice keyer.
Not really. It’s actually designed to record
snippets of off-the-air audio. It does let
you record your own messages — lots of
’em — in very high-quality audio. The only
way you can transmit them, however, is by
manually keying the PTT line and clicking
on the message file; initiating the message
alone does not trip the VOX! I also didn’t see
any way that you could rename the file (the
radio applies a date/time/frequency stamp) to,
say, “CQ contest.” A little digital rejiggering
could make this feature more useful.
To retain various audio-related settings
such as transmit or receive equalization you
must save the “transmit profile.” FlexRadio
includes several stock choices or you can cre-
ate your own. In addition to EQ settings, the
transmit profile saves the TX filter high and
low, compander and mic gain settings, lev-
eler parameters, RF output power and ALC
values. Very handy! I only wish the radio had
some way of saving various sampling and
buffer setting profiles that the operator could
access them with the click of the mouse.
CW Choices
New with the FLEX-5000A is a real
keyer plus provisions for CW keyboard-
ing, CW memories, dot-to-dash ratio and
waveform shaping. Even so, CW operation
was a somewhat less enjoyable experience
than SSB. While the manufacturer claims
the FLEX-5000A is capable of full-break-in
(QSK) CW, most CW aficionados would call
it “near QSK.” If another station can’t break
you with a single dit while you’re sending,
it’s not true QSK.
With the first computer, we experienced
CW latency — that pesky time lag. With the
delay set at 10 ms, the lowest it goes, sending
was choppy at a 192 kHz sampling rate and
a 2048 RX buffer. Operation with the second
computer was much improved. The optimum
nals will appear to ‘jump out’ of the noise,”
enhancing weak-signal reception. Dropping
the AGC gain also means less AF output,
hence the interaction. On the other hand,
audio dynamic range improves.
Making volume levels more uniform
requires tinkering with the AGC-T and AF
controls. The manual advises setting the
AGC-T control “as low as possible to comfort-
ably hear the signal of interest” (the default
setting is 90) while setting the AF gain to
a slightly louder-than-comfortable level.
I’m not sure I ever really found that “sweet
spot,” however.
The separate AGC control lets you set the
AGC action to slow, medium, fast, long or
custom. You also can turn the AGC off al-
together. It’s possible to customize the AGC
action via the
SETUP menu.
Gremlins?
We encountered a few transient gremlins.
With the Vista computer, the display driver
would quit momentarily from time to time
— at one point twice in the course of an
hour-long QSO. This typically occurred only
while using high sampling rates. On numer-
ous occasions I found it necessary to stop
and restart PowerSDR after it froze up on the
first try. Less frequently the radio would not
receive after the VOX dropped out. Briefly
tripping the PTT got it going again.
Other times I’d see this announcement:
“Error communicating with the FLEX-5000.
Please reload PowerSDR to try again.” Start-
ing PowerSDR too soon after energizing the
radio box can cause this, although that was
rarely the case. A further complication: After
clicking “OK” on the error dialog box, the
program continues to load, then gives you a
second
error message informing you that it
could not open the driver.
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
error message saying no RF was detected.
Other times I got nothing, although the ATU
remained in line, rather than switching to
bypass as it’s supposed to. Early on, I “lost”
the ATU function altogether and had to restart
everything from scratch a couple of times to
get it back.
A few times the panadapter disappeared
or failed to show the spectrum trace. Sam-
pling rate and buffer settings that seemed to
work okay initially later didn’t. Then too,
sometimes the driver buffer setting would
change mysteriously and without warn-
ing. At least once, the FLEX-5000A quit
receiving after I’d entered some buffer and
sampling rate settings the manufacturer had
suggested. FlexRadio attributes gremlins
like these to Vista and recommends using
Windows XP
unless there is a strong reason
to go with Vista.
CW setting seemed to be a buffer setting
of 512 at a 48 kHz sampling rate, although
filters are less sharp with a buffer that small.
The latency problems that plagued us on CW
with the SDR-1000 are pretty much gone
with the FLEX-5000A, however.
The CWX (keyboard/CW memory) menu
accesses nine easily programmable CW
memories (just type and play!) and keyboard
capability with a substantial type-ahead
buffer. I found these especially convenient
when using the FLEX-5000A as part of
the W1MGY Titanic anniversary special
event. Opening the CWX menu immediately
switches the transceiver to CW mode (and to
the last-known CW filter setting).
Using the type-ahead buffer involves first
putting the keyboard output on “pause,” then
activating the keyboard keys to type. To send
what you’ve typed, simply “un-pause” the
output stream. It’s possible to continue typ-
ing at that point, assuming you’ve still got
the keyboard activated. My CW preference
was a combination of the CW memories and
the keyboard.
A separate “Morse Definition Editor” lets
users define or redefine nearly each element
in the 64-character set. Send CW in German a
lot and want to sound like a native? Program
in those inflected letters (ü, for example), und
Du bist ein Berliner
!
The speed setting on the CWX tab is in-
dependent of the CW SPEED setting on the
main PowerSDR console. So are the various
timing/delay settings, which, depending on
your computer, may need a little diddling to
get just right. You may be able to achieve
near-QSK on the paddle, but you still have to
adjust the keyboard settings to get the same
effect. Very tight TR delay settings — near
QSK — introduce annoying pops and clicks
in the sidetone. In addition, if you’re listening
on the speakers you’ll also hear lots of relay
chatter from the FLEX-5000A box.
A Semi-Automatic AGC?
Without judicious use of the AGC-T (AGC
threshold) and AF controls, signals can and
will block or overload the FLEX-5000A and
possibly blow your eardrums. FlexRadio
concedes that users have posed “numerous
questions” related to the
AGC-T control,
which essentially acts like an RF gain control.
The fact that the
AGC-T and AF settings some-
what interact has given rise to considerable
explanation in the Owner’s Manual and the
online knowledge base.
Here’s the thing: The FLEX-5000A’s
AGC, which operates at audio frequencies,
seems to be something less than automatic.
The
AGC-T control adjusts the AGC gain
and, as the Owner’s Manual explains, “is
used to maximize the signal-to-noise ratio
based on band conditions (QRN).” FlexRadio
recommends reducing the AGC gain until
you reach “a sweet spot at which weak sig-