FT-817, Interface and Raspi4 in the rain

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.

CR Kits DSB Transceiver prototype (Source: CR Kits)

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.


  • 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

FT8 WSJT-X ALC einstellen

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.

Chinese Power Cable for Yaesu FT-450 FT-891 FT-991

I bought my Yaesu FT-891 to use it on SOTA-summits when I need some extra power that my FT-817 can't deliver. When I am out portable, I have the battery very close to the radio. Unfortunately for me (fortunately for the mobile users) the FT-891 comes with a massive and bulky 3m or so power cable. It's very sturdy and something you definitely do not want to carry. The weight is 270g. Just before I decided to cut the original cable in pieces and solder it together again I found a nice offer from China on Ebay. A short 4 pin Yaesu/Kenwood plug with a cable and fuseholder. It was only 4 Euro shipped (!) from Shenzhen. Delivery took about 3 weeks and I did not expect too much. First thing was that I check the resistance on all 4 pins. 0 Ohms. That was good. The fit is also like the original plug. No complaints there. I just fit Anderson Power Poles and tested the cord. Works perfect and now weights only 86g. I also do not consider the smaller AWG number (diameter) a downfall.

26" bicycle rim magloop

I was out for a walk in my city when I found this old 26" bicycle rim in the brushwood close to the rail tracks. I removed all the crusty stuff and added a  variable capacitor with around 15-120 pF. Some time later I was able to work RA3BL in Moscow 2.200 km way on 30m. The efficiency on 10 MHz is only 5% on such a small loop but it worked. I later worked LA9NKA on 12m, K8JDC on 17m, DK3KUD on 60m and highlight was VP8LP in Falkland Islands on 17m who was 12.700 km (7.900 mi) away. Unbelievable. I like this antenna a lot and can highly recommend it. I try to source some old 24" and 28" rims to compare them. 28" should be the best option there performance-wise but you need a capacitor with a low starting capacity, otherwise you probably lose 10m.

Yaesu FT-65 FT-25 FT-4XE FT-4VR

Some time ago I received a Yaesu FT-4XE. Programming, especially if you have to set a CTCSS, is a pain. I can tell you this is no joy. In the time that you spent in programming one chanel you can easily convert an old baofeng programming cable into one for the Yaesu FT-65, FT-25, FT-4XE or FT-4VR. I found a nice video on Youtube and needed only one minute to complete the project. With this easy modification I was able to programm all my local repeaters into the radio. As of today (Feb 2019) chirp does not support those new Yaesu handhelds yet. But luckily Yaesu has a free programming tool on their website. You can modify all parameter such as QRG, CTCSS, DCS, Power Level, etc. I had no spare 2,5mm plug so I just removed the 3,5mm plug from the Baofeng original one. GND was already correct, TX and RX had to be changed over and one diode (0,6V drop on my one) had to be soldered in. Life can be simple - sometimes.