Category Archives: FlexRadio Systems

Interesting Project – Teensy-Maestro for Flex-6000 radios by Len KD0RC

The TeensyMaestro by Len KD0RC is a Teensy (Arduino work-alike) based set of controls for the FlexRadio 6000 series. It provides knobs, buttons, display and a keyer. It is designed to augment SmartSDR (SSDR), not replace it.

The GitHub repository:

The FlexRadio Community Thread:

TeenseyMaestro #2 on the operating desk of of Dave Patton, W4WKU

From the TeenseyMaestro Readme File:


The TeensyMaestro is a Teensy (Arduino work-alike) based set of controls for the FlexRadio 6000 series. It provides knobs, buttons, display and a keyer. It is designed to augment SmartSDR (SSDR), not replace it. There are many functions that the TeensyMaestro cannot perform that still need to be done using SSDR or a real Maestro. The TeensyMaestro uses a USB cable for power and an ethernet cable to connect with the radio. All communication with the radio is via TCP/IP, not the USB cable. The primary design goal was to provide the most used controls in the form of knobs and buttons while retaining all the power and convenience of the computer-based SSDR. It uses the extensive TCP/IP Application Programming Interface (API) provided by FlexRadio. It also leverages the Flex Arduino library built by Enzo, IW7DMH. Without this library, the TeensyMaestro would not have been built. While the TeensyMaestro has a color touch screen, it does not display a panadapter or waterfall. It does show basic slice information in a similar way as the “flag” does in SSDR. The touch screen is a rudimentary resistive type, so it does not have cell phone like capabilities but provides some simple functions. There are no functions that rely solely on the touch screen; the physical controls cover all touch screen functions.

Using the Teensy.exe Loader to program the Teensy board

  1. Make sure the Teensy 4.1 is plugged in to a USB port

  2. Download the .hex file

  3. Download Teensy.exe if it is not already on your computer

  4. Run Teensy.exe

  5. Click File, Open HEX File

  6. Navigate to the file saved in step 2 and select it

  7. Click the Program button on the Teensy board to start the download

Interesting project and makes a lot of sense. I had done a sketch and pitch to FlexRadio Systems eight years ago on a commercial product that is much like this bench built project. Believe that my suggestions were premature and would have involved too large of a resource diversion from a project that eventually became the Maestro.

It is really neat to see Len KD0RC developing his project!



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Welcoming 2021 – First QSO if the year is DX with Yoon HL5BLI – Flex-to-Flex too!

A few Edits after communicating by email with Yoon HL5BLI


After my morning swim – also a first for the new year – I stopped at my office to do a couple small chores.  I ran up my remote Flex-6700 at the home QTH and set it to run FT8 while I watered my plants and fiddled with a new trackball mouse.

Wow – almost right away (after my second CQ K9ZW transmission) I hit a DX QSO from a country that is uncommon when I am working with my vertical on 30m.

It was HL5BLI Soo-won Yoon from Ulsan city, on the south east coast of South Korea. Yoon came in strong and we quickly complete our QSO.

It was really nice that first K9ZW 2021 QSO ended up being a DX QSO, and as I found when I looked up his call on, an all FlexRadio QSO to boot!

Yoon HL5BLI uses a Flex-6400 and I was using a Flex-6700 as we made the 10,400 KM (roughly 6,500 mile) QSO.   Later by email Yoon HL5BLI confirmed he was also operating barefoot and that it was also his first QSO of 2021!!

A very good QSO to start off my 2021 radio efforts!




An Update on a Bigger FlexRadio Systems (2020)

This arrived a few days before Christmas from FlexRadio:

Dear Valued FlexRadio Family,

I’m not sure how to paraphrase 2020 except to say that this year has taken us all by surprise.  As we approach the holiday season and the end of a very challenging year, I hope this letter finds you and your family well.  Here at FlexRadio, we have been fortunate to stay healthy and strong amongst the many challenges we faced throughout the year.  Like most companies, we have worked at home more than we have ever done before, but we have also had to make adjustments as our vendors have had issues. Supply chains have been strained, components have become unavailable and we even had a manufacturing partner close shop. While we’ve put our contingency plans in place for each of these challenges, as we have many times before, we have never had so many of these challenges arrive all at once demanding simultaneous attention. As a result, we’ve spent more time this year adjusting to the challenging business environment and less time communicating with our many friends that comprise our customer base. 

As the American novelist E. L. Doctorow famously said, “You can only see as far as your headlights, but you can make the whole trip that way.” So we, like most of you, found we must take it day by day and remain flexible to address the next challenge that lies ahead. We are truly grateful for your support and partnership during this time as we all face these unprecedented challenges of a global pandemic together.  Here’s what has been going on with FlexRadio in 2020.

The FLEX World Pre-COVID

We entered 2020 with an optimistic view of the opportunities in front of us.  In 2019 we won a large government contract in partnership with a division of Raytheon later acquired by BAE, which opened new doors for us in government and commercial HF markets. As we’ve mentioned before, we look for synergistic business opportunities that allow our amateur and commercial/government businesses to share technology and capabilities. It is exciting knowing that much of the technology developed in conjunction with this contract can be leveraged back into our amateur radio product line (and vise versa).

As has happened many times in the past, this new work has fostered growth in our company. Our engineering department alone has tripled in the last year. In the short term, many of these additions are assisting with our largest contract. Longer-term, many of these individuals will contribute to the amateur product line as well. With this unprecedented growth, you may imagine that we periodically discuss the role that amateur radio plays at FlexRadio. Any business leader would be remiss in failing to discuss the details of each product line and how to grow or phase out those lines as business dictates. As has been since the beginning, we continue to see huge benefits from our amateur business to the overall health of the company. Without exception, our key decision-makers have continued to reaffirm our commitment to the amateur radio product line and community. In short, we’re here to stay!

Since our last in-person interactions during Hamcation and the Yuma Hamfest back in February we have roughly tripled our employment and square footage.  Our new space has a custom build-out including two new state-of-the-art ISO-9001 certified engineering laboratories to accommodate this growth.  Growth has brought additional talent, equipment, and technology into the company that we would not have been able to acquire as an amateur radio only company. While it takes time to harvest the fruits of this expansion, we can already see many ways that you, our amateur customers, will be the beneficiaries.

Unbeknownst to us and the world at the time, our personal and working lives were about to drastically change.  We couldn’t have predicted that those first two hamfests of the year would have been our only face-to-face interaction with our customers in 2020.  On March 13, in the wake of COVID-19 realizations, we made a shift to “quarantine and work from home.” This impact on our daily lives forced us to construct new ways of doing business and engage with our customers. Of course, many or most of you are intimately familiar with the new way of working!

Since the early lockdown we introduced a complete brand refresh and launched a new website along with a new FlexRadio Community tool.  We’ve spent more time on customer education through increased presence on social media.  Our own Michael Walker, VA3MW, has conducted numerous Facebook live events on our FlexRadio Enthusiasts page on Wednesdays and Fridays around 2:30 pm CST.  If you missed them, these videos are also available on our YouTube channel.

COVID Era Challenges

The loss of one of our manufacturing partners led us to shift the load to our other partners (who were experiencing the same demands from other customers). Prior to COVID-19, our strategy had our manufacturing partners performing our test procedures on individual circuit boards, assembling these into finished units, testing these units, and collecting completed radios and accessories into a box that was ready to ship to you. We saw a number of benefits from this strategy, but it takes considerable effort to work with a manufacturing partner on everything from executing test procedures through ensuring a quality product is boxed before shipment.
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FlexRadio/4o3a TunerGenius XL – SO2R or 3-port version?

Last weekend Mike WB6DJI posted a very good question about the FlexRadio/4o3a TGXL TunerGenius and choosing between the two initial versions:

SO2R versus 1inx3out TGXL version debate

Placed my preference back in Sept 2020 for the1inx3out TGXL version with FRS

Never operated SO2R but have a 6600M and PGXL ( acquired over 3 years ago )

My Bands are 40 meter dipole with a 20meter thru 6meters using a HexBeam
Use my radio remote with a Palstar HF Auto for now

Thought 3 Bands Remotely would be good if I want to use 3 different antennas like with I do with the Palstar HF Auto

Been on the fence in trying to decide if SO2R is

Do not use 2 Bands at same time with My HF

I chase some DX but not in 24hr DX contests

What are your thoughts Steve



Mike WB6DJI followed this up with an email, as he too like myself is trying to figure out which version would work best for our particular station setup.

So everyone is on the same page the SO2R version (Single Operator 2 Radios) is optimized to rapidly alternate between essentially two parallel RF paths. The paths are distinct and cannot cross. I’ve read a 20ms path-flip number, once each path is stored in memory.  When the radio is a multi-SCU (Spectral Capture Unit) FlexRadio (6700/6600) the single physical radio is well suited to take the place of both radios in the SO2R equation.

The 3-port version is optimized for a single RF path and basically has a 3-port antenna switch integrated into the tuner.  There needs to be a separate feed line from the three possible antennas, one to each designated port.  I’ve not picked out a specific switch time, but the same 5ms for solutions stored in memory would seem likely.

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SDRSliceLabel launched by Ray Andrews K9DUR

Nice utility as announced by Ray Andrews K9DUR.

He has already done updates, and expect this nice add-on to evolve.

Sat, 14 Nov 2020 09:50:31 PST
I have just released a new utility for use with SmartSDR. The utility is named “SDRSliceLabel” and allows you to display customizable labels for each open slice in SmartSDR. Messages with different text & in different colors can be displayed depending on the slice frequency and mode. This is similar to the functionality provided by the BandText table in the PowerSDR database.

You can learn more about SDRSliceLabel on my website:

73, Ray Andrews, K9DUR




More on the FlexRadio/4o3a Tuner Genius XL

Recently 4o3a SkySat released a series of photographs of initial production Tuner Genius XL units by social media.

In their comments first production was reserved for Hams on “the list,” which likely reflects those who bought a PowerGenius XL/Tuner Genius XL combo.

I’ve not figured out if the photographed version is the SO2R model or the conventional tuner version.

Early production TGXL units

Cover off

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