Final Countdown

The Final Countdown starts today.

Exactly 100 days left until the biggest change in my radio career, with more impact than any transceiver, amplifier, or antenna.

SO2V with flexradio 6400 and N1MM+

As described in the previous post, I have configured N1MM+ in SO2V mode to work with the FlexRadio 6400.

To recap: the 6400/8400 only has one SCU (unlike the 6600/8600 which has two), which means SO2R is not possible. However, two “slices” can be received simultaneously, but only on the same antenna. On the other hand, N1MM+ interprets the two slices as two radios because two COM ports need to be configured.

In short: to make N1MM+ work in SO2V mode with a FlexRadio 6400/8400, the configuration needs to be set up as if it were SO2R. At least, that’s my experience. Other opinions are welcome in the comments section below this blog.

The settings need to be adjusted at five different levels: DAX, CAT, N1MM+, SliceMaster, and CW Skimmer, which does not make things any easier.

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1. DAX:
Here it’s important that both RX and IQ streams are enabled. Last time I had to restart the SMART-SDR software several times to achieve this. But there is a much simpler solution: if no panadapter appears, you need to select one in the SDR screen on the left in the DAX panel. Contrary to what you might expect, this is not the same DAX button as the one to the right of X/RIT.  IQ-streaming is importart because it is the input for Skimmer.

Using all this software is a field of expertise in itself. Especially when certain features are used only occasionally, important items are quickly forgotten.

2. CAT:
Here the key is to provide a COM port for both slice A and slice B.

The choice of COM ports is entirely up to you, as long as they match the N1MM+ configuration and are not already in use by another Windows application.
VFO 1 (also called slice A) in my setup is linked to COM6, while VFO 2 (slice B) is linked to COM10. I also need a PTT link on COM7 (and COM11 for slice B), a Winkey link on COM9, and a UDP port 12060 (on the picture it is 12061, but better set it to the standard 12060) for sending spots. I’m not entirely sure how well this last one works, because the spot management is handled by SliceMaster (see below).
Finally, outside of contest use, there’s also TCP port 5003, which is used by FT8-WSJT.

 

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3. N1MM+ configuration:
As mentioned earlier, the choice of ports is free, as long as they match the CAT software settings within SMART-SDR.
Here are the parameters per port, with the most important note being that “SO2R” must be checked — not SO2V, even though the latter might seem more logical.

 

 

Configuration of the broadcasting :

Port 7811 is used for a home-made application in Python that does a realtime QRZ.COM lookup of every worked call.

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4. SliceMaster:
This software makes it easy to link external programs to SMART-SDR. During contests, I use it for Skimmer and spot management; outside contests, for example, I can run two WSJT sessions simultaneously — for instance, listening at the same time on 50.313 MHz and 50.323 MHz.
The most important settings can be found here:

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5. Skimmer:
This decodes the CW signals for the two separate VFOs and adds them to the Telnet server. It’s very important that the Telnet session from N1MM+ is linked to Skimmer and not to a DX cluster. For this reason, the password in the Skimmer configuration must be disabled.

Below are the different configuration screens for Skimmer slice A and slice B:

 

Never use the reserved channels, always take IQ RX1 and IQ RX2.

  

EU HF championship 2025

Because a planned BBQ was canceled, I unexpectedly had some free time to participate in the European HF Championship. Getting the SteppIR up in the air was a bit too much work, as the boom plate (see previous post) still needs to be mounted. I wasn’t expecting any big results, so it was a good opportunity to run a few tests:

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1. Test of the new 80-10m Windom antenna, bought during the recent sale at WIMO.

I already have sufficient experience with the 160-10m version, but since that antenna is over 80 meters long, installation takes quite a bit of effort. I purchased the smaller version so I could hang it on the north-south axis, as opposed to my G5RV which has to be hung east-west. The advantage of a Windom antenna is that it has a short leg (toward the house) and a long leg (toward the garden).

According to the manual, the antenna works on 80/40/30/20/17/10m—so not on 160m or 15m. On 160m, the analyzer showed an SWR between 1.7 and 2, and it was perfectly usable across the band. 15m indeed required more effort from the tuner, but it still managed to match it well enough for operation.

For this contest—where DX yields no points and the coverage area is very similar to the fieldday in the Restricted category—this was the ideal antenna.

The idea is also to test this antenna in the context of field days. That’s why I chose to hang it at “only” 14 meters (Field Day rules allow 15m) and to operate with a maximum of 100W (as prescribed by the Field Day regulations).

Log analysis indeed shows two nulls to the north and south, just as expected. However, the benefit now is that the northern null covers mostly water and very little land.

With 775 contacts across all bands, the result exceeded expectations.

This map, based on the ADIF file, has been created with "https://qsomap.cqgma.org/ADIF_to_Karte.php"

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2. Test of the Flex6400 + PowerGenius + TunerGenius combo.

I was particularly interested in how this setup handles rapid band and segment switching, and whether the mandatory 20ms delay causes issues in CW—specifically, not hearing the first dit or dah.

Since I wanted to participate in the low power category, I set the drive power to just 1W. This resulted in output power ranging from 75W to 85W, depending on the band, which was sufficient. After all, I wouldn’t dare run a 100W transmitter at full power for hours straight during fieldday. On 160m, the output just exceeded 90W.

To configure the tuner, I went through all bands before the contest so the values would be saved in memory. During the contest, it felt as if there were no switching delays. This thing works perfectly.

 The amp—still quite noisy even at minimal output—did throw a single SWR error. Cause unknown, but acceptable given it’s a wire antenna. However, it also completely froze once (a hard reset was required). That’s less acceptable. Sure, it all works over a LAN with various types of traffic, but that shouldn’t be a problem.

3. Test of N1MM+ in SO2V mode.

The configuration cost me a lot of time and frustration. I’ll write a separate article about it for future reference and to help others. In short, the FlexRadio6400 (and 8400) does not support SO2R since only one antenna port can be used (antenna ports A en B work like a switch) at a time. But 2 slices can be configured and they are able to receive simultaneously. However, N1MM+ must be configured as SO2R (not SO2V) because each of the two "slices" requires a separate COM port and is therefore treated by N1MM+ as two separate radios.

There were also the expected issues with using DAX and IQ streaming to feed the two skimmers and forward the output to N1MM+ (Telnet and port issues).
IQ streaming, in particular, caused problems—due to the SDR software—because the second stream sometimes wouldn’t start for no apparent reason. Power-cycling and restarting resolved the issue. This will be a focus for future contests: let the system run for hours beforehand so that nothing needs to be configured at the last minute.

The result, however, was fantastic—ideal for a wire antenna (or a tribander with a single coax).

Two bands were received simultaneously the entire time, and for the first few hours, I only did S&P. Running would likely yield more contacts, especially in the high power category, but even with just 80W, I could generate solid rates simply by clicking from station to station.

When enough red (multipliers) showed up on the second band, I could switch instantly and start again. This gives a massive strategic advantage in any assisted category. It's nothing like cluster input, because each skimmer signal was received on my own antenna and was instantly workable.

This is how you win Field Days with a minimum number of operators.

The contest itself was pleasantly busy, and I had enough time to configure the global layout on the screens.
Since I pushed through to the bitter end (2 AM is a real grind), there was no more competition left within ON. My neighbour, ON5JT, was a good competitor during the first hours of the contest, but then stopped operation at the evening. Our (few) signals were quite comparable.

My score will be somewhere in the top 25, not bad for an multiband wire antenna that isn't made for 15m. 

Prototype of the home designed alu plate arrived

Once again, a small stone has been laid in the river of ongoing projects: an aluminum plate, designed by myself, that aims to solve the shortcomings of the mini-tiltplate.

Although the tiltplate plays a crucial role in my station for antenna selection, it comes with several limitations:

• Each type of Yagi boom requires a different solution. Usually, the boom can be mounted inside the tiltplate, but for certain types—such as the 80mm square boom—more complex technical workarounds are necessary.

• Aligning round boom tubes is a slow and painstaking task.

• For larger antennas, my mini-tiltplate is inadequate due to a lack of sufficient mounting points.

• When a vertical boom truss is required, the mini-tiltplate offers no solution.

After much thought, I’ve come up with a solution that addresses all these issues: an adaptive aluminum plate that fits the chosen antenna perfectly. It is pre-mounted on the antenna boom and can be easily connected to the tiltplate using seven M10 bolts, with respect to the karlock security system. 

Ensuring that the antenna hangs perfectly horizontal is now achieved with two adjustment screws spaced at the correct distance—no more hoping that things will align properly once airborne, but rather having certainty in advance. That makes a real difference.

My first prototype plate was delivered this week.

Fixed vertical positioning, independent of the used antenna.

Original mini tiltplate.

This plate can easily accommodate both the OB5-10 with a round boom in combination with the SteppIR, as well as the OB2-40 with an 80mm square boom.

The Dutch company (www.laseropmaat.nl) that cut the plate works with input based on a DXF file. It was a bit of a throwback to my mechanical AutoCAD drawing days—over 30 years ago—to get this drawn. LibreCAD is a free piece of software that can generate this type of file.

The result meets all expectations. I was a bit nervous checking whether any measurement errors had slipped in—but fortunately, everything turned out perfectly.

The next step is getting the Yagi back in the air.

This opens the path for the use of several bigger monoband antennas that can be installed within minutes.

IARU 2025 as operator in the OP0HQ team

Twenty years after my first participation in the national OP0HQ contest team—back then with ON4UN on 40m CW—I unexpectedly found myself part of the national team once again. This time, I was responsible for 10m SSB. Last year, I had already used this band slot to test the Optibeam5-10, which resulted in a very disappointing 250 contacts and the impression that conditions were exceptionally poor.

This year, propagation on 10m was even worse, and I only managed to log 271 contacts. Admittedly, there were a few nice ones from the African continent and South America, including the Falklands, but not a single contact with the USA or Japan. The trend was similar across all competing headquarter teams, but as usual, zone 27 was hit the hardest. It’s tough to transmit for so long with so little to show for it.

Shack improvement almost done

 

The shack upgrade is now nearly complete. 

Installing and integrating the various devices from the FlexRadio/403A family has so far been accomplished with just a few mouse clicks. The first impression of the tuner is that it’s worth its weight in gold when it comes to wire antennas. The amplifier is lightweight compared to a tube amplifier, but the ventilation system is louder than I had hoped.

Now it's just a matter of waiting for the ordered Genius 8x2 antenna switch to arrive, and then deciding whether to add a second transceiver—either a FlexRadio 8600/Aurora 520 or to stay with the 6400 for a while and buy a new one when software v4 is available. The goal is to be fully operational in the shack by spring 2026, and to have the antennas renewed by summer 2026. The coming months will be focused on 50 MHz, and then shifting to 80 and 160 meters from autumn onwards.

All installed on a single PC table and easy to disconnect in case of thunderstorm.

DXCC 323 : Prince Edward & Marion Islands

Once again, a rather unexpected last-minute expedition to a rare DXCC. 

And once again, the wrong antennas were in the air. 

This time, ZS8W was active on 10 meters—a piece of cake to work with the Optibeam, if only it hadn’t been lying on the ground while the SteppIR was up in the air. In the end, I still managed to make the contact in FT8. LoTW confirmed and QSL received. 20 DXCC to go.

Then a pleasant surprise: I worked them on 30 meters using the G5RV wire antenna. Although this band isn’t ideally suited for the G5RV, I was able to tune it with the new TunerGenius. To my amazement, he came back to my call immediately. Upon further investigation, it turns out there’s a very interesting radiation pattern on 30 meters, which happened to be perfect for the southern direction. And once again it proves: a seemingly poor antenna works a hundred times better than no antenna at all.

30m pattern on normal G5RV