Switching Computers Midstream

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

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

1.6GHz. 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

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.

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.

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-

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- ring as it tries to come to terms with whatever load you have attached to one of the three SO-239 connectors on the box’s rear apron (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 an optional full-featured second receiver, known as RX2, was poised to provide the potential for SO2R — single-operator, two radio capability — in

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.

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, the mouse has become the de facto control- ler for programs ranging from accounting to 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.

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-