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
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-Tcontrol, which essentially acts like an RF gain control. The fact that the AGC-Tand 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-Tcontrol 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-
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-Tand AF controls. The manual advises setting the AGC-Tcontrol “as low as possible to comfort- ably hear the signal of interest” (the default setting is 90) while setting the AF gain to
aslightly 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.
