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My Thoughts on...

What is a Flex?  Why did you get a Flex?  Do you like the Flex?  I’m often asked one of these questions when I come across a contact on HF, whether in general exchanging of working conditions (equipment at your station in use) or in a rag chew.

What is a Flex SDR: FlexRadio Systems is a manufacturer of amateur radio transceivers located in Austin Texas here in the U.S.  FlexRadio Systems is a pioneer in SDR (Software Defined Radio).  Unlike conventional radios or transceivers with knobs and buttons, a SDR rig is controlled and operated through a software program loaded on a personal computer system. 2017- Flex now offers SDR rigs like the 6400 or 6600 M models which have front panel interfaces containg your most used knobs, buttons and easy access to other features. All the 6000 series rigs now have built in computer systems which contain the operating system, firmware and allow for easy network setup, allowing you local access or worldwide access to your ridao via a locall network or remotely by an internet connection. 

The SDR radios can be connected in several ways via a serial, USB, Fire Wire, or Ethernet port with Ethernet being the preferred choice since it offers the faster throughputs, greater bandwidths and lowest latency.

It’s a much different experience - having a screen displaying information about incoming and outgoing signals.  After the initial awe and visual overload of what was going on, I found it to be very informative.  Suddenly realizing I could see a wealth of information on what was happening, where, and in what modes. 

Wow, no more listening for a station as you tune a dial, this was neat.  By simply looking on the display and clicking on a signal, you’re tuned to that frequency (okay getting proficient at being right on them took a little practice, but by scrolling with the mouse wheel you can fine tune things in).  The old analog way of spinning a dial for hunt and pounce seems obsolete and crude when compared to visually seeing a signal.  This is so much faster, and you can literally see just where all the stations are when a DX station is working split and listen up.  You see where the signals are and can find a niche where it is less crowded, standing a better chance of making the contact.  After having used the pan adapter display on an SDR radio, especially on a FlexRadio Systems unit, I just feel lost without that informative display of information.

Why I chose a Flex: I have been a computer tech for over 20 years, so computers do not scare me.  I enjoy building computers and using the latest hardware and software. SDR radio appealed to me as different, a newer technology where software and hardware working in tandem interested me.  (I’ll be the first to say if using a computer scares you, don’t get an SDR.)  However if you can surf the internet, use an Office program, check your email, have installed some basic computer hardware or accessories along with some software, then you should have no issues in setting up and using an SDR.  Put aside the notion that if you click on something wrong it will mess up, or it will be a pain to configure, and that isn’t radio.  Those who complain and bad-mouth SDR and the software probably have daily issues with following directions or tying their shoes, let alone even turning on a computer.  To those types, just stick with being an appliance operator.

Since Flex SDR rigs are controlled by software using a computer, they are connected by a single cable to the computer (with the exception of the earlier SDR-1000 models which required an audio interface via a higher end sound card) and all of the rig controlling and audio can be sent over that single connection.  This means one cable for rig control and audio interfacing making data modes a real breeze (no external interface is required), and with the use of VAC (Virtual Audio Cable) software, all that audio can be kept in a digital format making it superior to converting between analog and digital and back again.  Using the data mode software, you simply select your virtual audio in and out cables and you’re off and running.  No need for an extra interface, more cables, and trying to get it all to work with correct audio levels and retaining a correct ALC range.  Speaking of audio, the Flex PSDR software has many advantages over the common audio settings and menus of conventional rigs.  There is a selectable Off, 3, or 10 band equalizer available for both TX and RX, a Compander (a form of compression), an Expander (a way to control background noise that attenuates a user selectable level of audio below that threshold) and a Leveler that keeps your audio at an even ratio during softer or louder peaks in your speech.(2017)  As of the 6000 series the CAt and DAX aduio interfcases are built into the software so no 3rd party applications are required for virtual com ports (CAT) or Digital Audio Exchanges (DAX), easy setup of just about any digital mode and logging software, een easier if the software supports the flex API. 

You can setup multiple audio profiles for different needs, perhaps a rag chew mode, general audio, and a DX mode.  And since no two digital modes seem to require the same level of input and output to keep the ALC in line, you can setup each mode with a different profile tailored to its specific needs then name and save it.  Now, by simply clicking on its profile name from the drop down list you’re off and running; no need to readjust again between different modes of operation.  It can take a little time to get your audio the way you want it.  Whether you like conventional audio bandwidths or enjoy the ESSB sound, it can be tailored to suite your preference.  I’ve received many compliments on nice audio, clean and smooth, or good DX punch depending on which profile I need at the time and for conditions at hand. (August 2013- I am currently using a Sterling Audio ST51 condensor microphone, into a Ultragain MIC2200 and a little more EQ tweaking via a Ultra Curve Pro 2496 which is input via the DB9 connector on back on the 3000)  The receive audio is exceptional as well, non-fatiguing to listen to for extended amounts of time, like during contesting.  You will need to provide some powered speakers since none of the current FlexRadio Systems rigs have built-in speakers or an on board audio amplifier.  If you have a computer, you probably already have a set of speakers anyway.

Bang for the Buck, a FlexRadio Systems rig is a hard radio to beat, especially the middle of the line model Flex-3000 currently retailing for around 1600-1700 dollars new, and prices of 1200-1400 dollars used (yes they have good resale value when compared to convention rigs).  You get a 100 watt rig, built in auto-tuner, 160-6 meter coverage in 12 modes, LSB, USB, DSB, CWL, CWU FM, AM, SAM, SPEC, DGL, DGU, and DRM.  They have a quiet receiver.  Take a look at the Sherwood receiver reports.  FlexRadio Systems SDR rigs are in the top 10, competing with rigs costing several thousands of dollars more, many of which have limited pan adapters, costly optional pan-adapters, or none at all.  No need to buy or replace filters (since they’re all done via the computer).  How about the ability of dropping your CW filtering down to 25 Hz with no ringing?  It’s great for busy CW bands or contests.  Try that with many rigs today, many of which start ringing or sounding bad below 250 Hz.  Add in multiple TNF (tracking notch filters) allowing you to place up to 18 separate notch filters each varying in bandwidth and depth for notching out interfering signals or noises, and they can be saved and automatically recalled and activated when switching bands.  Two remarkable adjustable noise filters whose settings can be saved per band and profile.  Easily upgraded via software downloads that contain both firmware updates and new features, your rig doesn’t get out-dated and keeps current with band changes or adjustments.  When the 60 meter band changes went into effect, Flex users were some of the first ones to use the new modes and channels. (Flex 2018 best band for buck I feel the Flex-6400 is a great choice)

Do I like the Flex: Very much so.  It is a remarkable rig that excels in performance at a very competitive price. Being able to view a large portion of the band on the pan-adapter and seeing just where signals are, or aren’t depending on the case, is a huge advantage.  As I stated, I wouldn’t want a rig without it, or one with a small, limited, and hard to view display.  First-rate service and customer support is offered by FlexRadio Systems (great response time to phone calls and emails, and an online trouble ticket system to keep you updated on resolving any issue you may have).  When band changes are implemented, it’s a quick download of the new software package. Firmware updates and bug fixes are as easy as downloading an updated software driver or revision.  You get a nice quiet receiver that has a very selective front end with the ability to provide easy copy for weaker signals that is outstanding.  You can tailor and save your TX and RX audio profile settings as opposed to having to reset things between operating styles.  I truly enjoy using the Flex every time I turn it on.  With every PSDR software update it only gets better and better.  Don’t forget FlexRadio Systems rigs have a 2 year limited warranty, not 1 year or 90 days like those manufactured outside the U.S. So what’s not to like?

FlexRadio Systems website -

Sherwood Engineering Inc. -


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