Flexradio 6400 crashes after succesful upgrade due to bandswitch

It has always been my weakness: the fear of updating a working system with a complete lock-up as a possible consequence. For this reason, until this weekend I was still running SmartSDR v3.1.11 on the Flex 6400, while the latest version is now v4.2.20.

Due to the many crashes this weekend during the CQ WW WPX CW contest—crashes that are known bugs when N1MM+ strings are broken down too quickly in CW—it became clear that it was time to change versions.

When the pain of crashing during a contest becomes greater than the fear of no longer getting the transceiver to work, that’s when you end up doing an upgrade.

All the more so because the latest version includes a complete overhaul of the DAX and CAT control software. For those unfamiliar with FlexRadio, this may sound like Greek, but those who do know it understand that these are crucial parts of the system and the interface with external programs.

Since I have never used my Flex via the internet—only locally via Wi-Fi, never remotely over WAN—I wanted to make sure that my details in the central database were correct, to avoid suddenly being forced to purchase a new software version. To be fair, when I opened a trouble ticket with the Flex helpdesk, the response came extremely quickly that everything was in order, and the upgrade instructions were clearly explained again. We are not used to this kind of performant helpdesks in Belgium; perhaps that’s where part of the hesitation came from.

So, following FlexRadio’s recommendation: remove all old software, including all drivers, from the computer and install the new software. To my surprise and relief, this went without any problem. Next, the transceiver itself is upgraded from the PC. That also went remarkably quickly and smoothly.

The software even seemed to run immediately. N1MM+ appeared to work, and WSJT took over without issues.

Until I switched bands from 20m to 40m. Crash! Transceiver rebooting, software disconnected. And this happened repeatedly, with no way to get it running again.

Knowing it was the middle of the night in the USA and therefore no helpdesk available, I searched online and found that this error had occurred before (also to the great frustration of users). The only option seemed to be a factory reset. After looking up how to do this—and accepting that all parameter settings would be lost but the transceiver would at least start again—I performed the reset, and everything is now working as it should.

It remains a rather special concept: a radio packaged as a black box where there is little you can do except press the power button.

But I remain an absolute fan! And you can rely on the helpdesk, because they even replied later to my message about the crash. Now let’s hope everything stays stable, and that we don’t end up in a situation like SteppIR, where FlexRadio suddenly goes in a military or other commercial direction and abandons the amateur radio market.

First big test of the 20m yagi as part of OP0HQ in the CQWPX CW contest

The proof of the pudding is in the eating, and it tasted great.

The first major test of my 20-meter station lived up to expectations. With 2,352 unique contacts on the 20m band, it made a significant contribution to the OP0HQ multi-multi distributed score, to the extent that we can now claim a new European record as a group.

The ability to power-split using the wire antenna also proved beneficial in a number of cases, although its impact is negligible when viewed against the total score.

With the 20m team ON5ZO/ON7GLF/OT1A, we certainly could not complain about operator quality, despite the fact that this was the visitors’ first experience with FlexRadio.
Here, I must plead guilty: because the radio was still running software that was six years old, combined with the unfamiliarity of the CW bugs, the radio crashed several times and valuable time was lost.
Mea culpa. The latest version of Flex software is now running on my 6400.

On top of that, we lost an hour due to nearby thunderstorms, which caused heavy QRN and forced us to lower the mast and completely shut down the station. A score of 2,400 QSOs was therefore definitely within reach.

I am very pleased that the Momobeam antenna performed exactly as expected.

The next appointment is during the WWA Sprint Week as OP0WWA, and of course during the HF IARU Championships as OP0HQ.

It is also interesting to compare with other major stations, preferably those that are known for operating within the rules and not relying on excessive power. 

Below are the signal strengths of DR1A, LX7I, and OP0HQ@OT1A on the second day of the contest, as observed toward the USA.

It is noticeable that all three stations are closely matched. However, as I rotate toward the east during the day, DR1A remains stronger toward the USA, which suggests power-splitting across their famous stacked Yagi arrays. 

In a single direction, I certainly did not have to concede anything, but with their multiple antenna systems they are naturally—and rightly so, considering all their investment and effort—stronger in an omnidirectional sense.

First place 2026 UBA DX CW contest 12h low power

It has been since 2007 — almost 20 years, for heaven’s sake — that I last achieved a first-place finish in the UBA DX Contest.

To be fair, I should add that it is also the first time in 20 years that I have actually set aside a few hours to take part seriously.

For me, the UBA Contest has always been a stepping stone between entry-level contests such as the ON Spring and Autumn Contests and the more serious international competition. I felt it wasn't really fair to keep winning prizes in this contest year after year and never give newcomers the opportunity to experience the feeling of winning themselves.

This year was also a test to see what I could achieve with a wire antenna running low power. However, I must honestly admit that the multipliers on 10 meters with the 5-element Yagi made the difference.

For the 2027 edition, I would also like to find out what the wire antenna / 20-meter Yagi combination can contribute to the final result.

Still, I’m pleased to have been rewarded once again for 12 hours of Morse code.

Largest antenna project for 2026 successfully completed.

 

Final result :  Momobeam Mono 4-20 and the Optibeam OB1-30

What was originally planned for the IARU HF World Championship in mid-July, I ended up completing a few months earlier with the CQ WPX Contest at the end of May in mind. This time, it’s a 4-element for 20m from Momobeam, so it can be used in more conditions and over more years than a 10 or 15 meter antenna.

This builds further on the 10m monoband project from a few years ago, with the same foundation: easy ground-level assembly of a large antenna without needing additional people.

The added challenge here is the mandatory suspension of the antenna. In my 10m project, I had already incorporated the option of an extra tube acting as support for suspending the yagi, but I could omit it if another antenna was mounted higher.

This time, installing a suspension was a must—the boom length is 8.6 meters—and with a dipole above the yagi, this creates issues: the extra tube needs to tilt over the motor’s top tube, otherwise the suspension ropes would get blocked against it.

I found the solution by installing two suspension points, high enough above the yagi to provide a sufficient pulling angle, but just low enough to avoid touching the dipole. This way, both ropes can be tensioned properly.

This antenna, weighing 33 kg with a wind load of 0.92 m², is pushing the limits of my mini tilt plate (rated at 35 kg and 0.93 m², albeit at 160 km/h wind). The plan is to lower the mast at wind speeds of 90 km/h or more. 

It’s still quite something to see these dimensions laid out on the ground—this is no small antenna.

The installation went flawlessly. The instructions and labeling from Momobeam are truly excellent. The only calculated risk was raising it in 45 km/h wind. It’s hard to predict in advance how the mast will behave during tilting when a gust hits.

As a quick test, I played around on FT8 with the antenna at just 9 meters height. The results look quite good, and the SWR is perfectly flat in the CW segment, exactly as intended.

Stations that received my signal, yagi directed to the USA.

DXCC 324 : T31TTT Central Kiribati

Not my big favorite — I haven’t forgotten my unanswered Burundi case on 160 m with this DX group — and it’s not even the hardest among the remaining countries I still need to work. 

Still, I didn’t take any risks. I took the SteppIR out of retirement once again and put it back up to make sure I could work T31TTT. It’s clear that a 10 m monobander alone isn’t suitable for working rare expeditions. 

The risk that they won’t activate the band, or that conditions won’t allow it, is simply too high. With the SteppIR, it was relatively easy to work them on 15/17/20 m. Checked off.

CQWW CW CONTEST 2025 : final result

 

Not a top result. 

4th place on the all-time national ranking but 27% below my 2013 record.

It seems that during this contest no national records were broken, so it indicates also the state of propagation during the weekend.  

Good but not exceptional.

Good news : Not one penalty for lost multipliers is a good evolution.

Bad news : Some interference with OT2A this time (he was all band, so probably showed up in another color on 10m band).

************* Stations Copying OT1A Incorrectly **************

28029 CW 2025-11-29 1154 G4C      14   OT2A     14 
28030 CW 2025-11-29 1157 G0BNR    14   OT2A     14 
28029 CW 2025-11-29 1159 R7OV     16   OT2A     14 
28029 CW 2025-11-29 1200 SV1JFL   20   OT2A     14 
28029 CW 2025-11-29 1202 PY3RK    11   OT2A     14 
28116 CW 2025-11-29 1403 YL2KO    15   OT1T     14 
28070 CW 2025-11-29 1717 WB3X      5   OT4A     14 
28073 CW 2025-11-30 0824 HS5ZLD   26   OT2A     14 
28081 CW 2025-11-30 0852 R7NQ     16   OT1R     14 
28082 CW 2025-11-30 0954 G3SWH    14   JT1A     23 
28000 CW 2025-11-30 1051 SP3HLM   15   OT1T     14 
28060 CW 2025-11-30 1647 W7GTF    03   OT1QA    14 
28000 CW 2025-11-30 1754 HC2GRC   10   WT1A     05 

Very bad news : my dit-disease.  I sometimes have problems with a dit.

*********************** Incorrect Call ***********************

28030 CW 2025-11-29 1200 OT1A     14   DM2W     14  correct DM3W  
28036 CW 2025-11-29 1252 OT1A     14   DL5E     14  correct DR5E  
28106 CW 2025-11-29 1421 OT1A     14   HG6T     15  correct HG7T  
28009 CW 2025-11-30 1026 OT1A     14   YO4FSU   20  correct YO4FHU
28056 CW 2025-11-30 1217 OT1A     14   LU7HFE   13  correct LU7HF 
28060 CW 2025-11-30 1402 OT1A     14   F4FSV    14  correct F4FHV 

160m DXCC

 

The icing on the cake after years of strategizing and searching for the best solution to achieve DXCC on all bands from 6 meters through 160 meters. 

Also the last certificate for a long time, as the cost of American awards is starting to get out of hand.

A 10-Band DXCC once seemed unattainable, but by focusing on one band at a time, using the right antennas, and investing enough time and perseverance, it was ultimately achieved.