Recently, I saw a newcomer's post on Twitter regarding his first WSJT-X session. I noticed right away that he only decoded a handful of stations, but those with supposedly extremely good reports. This is what happens when you set your receive bandwidth extremely low. This means that you only receive signals that lie within this range. If we remember again our education, we find out that a normal report refers to a bandwidth of 2.5kHz. In this articel I explain the fundamentals about that.

Some time ago I already built some "loose" interfaces for my FT-817. I used these later on my FT-891. The CAT, respectively the FTDI USB to serial converter I needed at the FT-8x7, I don't need at the FT-891 anymore, because it already has CAT via USB integrated. The FT-891 simply uses a Silicon Labs CP2105-F01 USB/Serial UART converter internally. As with many other TRXs, this is not galvanically isolated, but the engineers thought of something. Apparently it works well anyway. I have had no problems at least in the last 2 years. In this article I show you my solution for this problem.

Today I drove to my nearest SOTA summit (DM/SR-012, Schaumberg) to test my recently bought Raspberry Pi4. Up to now I had a Pi3, but it was too slow sometimes. Today I wanted to do a dedicated SOTA activation in FT8. I have done FT8 from a summit for SOTA before, but always only besides SSB. With -1°C and freezing rain, it was exciting not only for the operator but also for the technical team. Spoiler: When I came back into the warm with the Pi4 it cracked and the blade from the fan broke out of the case at all 3 points. Well, a new one does not cost 2 Euro in China. Of course including shipping. On 40m I was heard well, also in England. But after 15 minutes there was only one station in the log: S57ILF. In SSB my log would probably have been well filled already. On 30m it was better then. At least 5 stations came into the log. Because it was very cold I skipped 20m and called a few times on 17m. K1KZ came into the log.

Today I was browsing through the SOTA-reflector (the SOTA forum if you like to call it so). I found an interesting post from Richard, G3CWI about a new chinese developed 1W datamode TRX with built-in VOX. So you don't need any CAT to trigger the PTT. I checked out the groups.io thread (DSB transceiver for Digital mode) with lots of useful questions and information. Especially paired with a raspberry pi that would be an ideal SOTA and /P rig I guess.

Specs:

• Crystal controlled single frequency DSB transceiver for 20m (14.074MHz), 40m (7.074MHz) or 80m (3.573MHz), other frequencies could be added per request. 80m is not ready yet.
• Power supply: 10-14V DC regulated power supply or battery pack, 12V is recommended, center positive, reverse polarity protection available

Ich habe 2015 mit JT65 angefangen und auch ein paar Monate primär JT9 gemacht. Es kamen so mehrere Tausend QSOs zusammen. Anfangs ging es dort sehr gesittet zu und die empfangenen Signale waren allesamt sehr sauber. Für mich war das damals die ideale Betriebsart, um mit meinem FT-817 und 5W "ungestört" mit QRP schöne Verbindungen zu machen. Irgendwann kamen dann die dicken Stationen mit immer mehr Leistung dazu. Man konnte sagen, dass das Spektrum mit zunehmender Leistung unsauberer wurde.

Rein technisch ist es natürlich möglich, auch mit hohen Ausgangsleistungen ein sauberes Signal zu senden. Ich habe das Gefühl, dass seit der FT8-boom eingesetzt hat, einfach nur drauf los gefunkt wird, ohne dass die wichtigen Einstellungen geprüft werden.