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.