I recently spotted the Tokmas CI7N170SM TO-247 part on LCSC. It seems like a pretty neat part for building non-QRP HF amplifiers! This could be a better part for our Baby QRO amplifier. Datasheet Excerpts The full datasheet is available here. Comparison In comparison, here is what a professional RF part (MRF300AN) looks like: That 272W maximum power dissipation figure is crazy good but switching characteristics are not that great (fast).
While running https://github.com/fhoedemakers/pico-infonesPlus, I found that my SNES gaming pad was not fully supported. Specifically, the UP/DOWN and LEFT/RIGHT keys were not working. Let's debug this a bit: Plug in the gaming pad on a Linux box and run the following command (hidraw5 will need to be changed as needed): $ lsusb ... Bus 001 Device 063: ID 0810:e501 Personal Communication Systems, Inc. SNES Gamepad $ sudo hexdump -C /dev/hidraw5 ... 00004a50 01 80 80 7f 7f 0f 00 00 01 80 80 7f 00 0f 00 00 |................| 00004a60 01 80 80 7f 00 0f 00 00 01 80 80 7f 00 0f 00 00 |................| * 00004a80 01 80 80 7f 7f 0f 00 00 01 80 80 7f 7f 0f 00 00 |................| This is what I see when pressing the UP key. ...
Here is the FT8 WAV test file. On an AMD64 machine: 1 second using the fast decode settings. We were able to get the MSHV's FT8 engine to work on Android, thanks to the work done by https://github.com/sannysanoff/SDRPlusPlusBrown folks. Around ~4.5 seconds to decode the same file. This is why we can't really have full-blown realtime FT8 decoder(s) on Android just yet! Idea: But we can surely use this full-blown FT8 decoder in our FT8 Decoder app which has no realtime requirements! ...
OCXO's are awesome - this is what I learned while trying to get WSPR working reliably on the 2m band. Hardware Here is all you need for reliable WSPR'ing on the 2m band: A RAW OCXO "can" works fine too! Note: This modified Si5351 board image comes from SimonsDialogs. Essentially, we modify the CLK2 output port to become an input port that accepts the OCXO's output signal. ...
Circuit: DDX-Commercial-7 Antenna: Small jumper cable attached Initial Results 10m: 36 dB on WSJT-X audio meter, on quiet and also with nearby beacon on !!! 12m: 36 dB on audio meter, on quiet and also with nearby beacon on !!! 15m: 46 dB on audio meter on quiet, 65 dB with nearby beacon on - OK 20m: 44 dB on quiet, 65 dB with beacon on - OK 40m: 40 dB on quiet, 60 dB with beacon on - OK ...
Notes to get Vivado 2025.1 running on Ubuntu 25.04 (plucky) Linux distribution. Original reference: QMTech XC7Z020 Notes Setup Install dependencies: sudo apt-get update sudo apt-get --no-install-recommends install \ bc binfmt-support bison build-essential ca-certificates curl \ debootstrap device-tree-compiler dosfstools flex fontconfig git \ libncurses-dev libssl-dev libtinfo6 parted qemu-user-static \ squashfs-tools u-boot-tools x11-utils xvfb zerofree zip Hack deps a bit: sudo ln -s /lib/x86_64-linux-gnu/libtinfo.so.6 /lib/x86_64-linux-gnu/libtinfo.so.5 You can now go ahead and run the Vivado installer. ...
Note: This HF LNA design is inspired by Charlie Morris ZL2CTM's prior work. Design The idea that a single-transistor preamp with 10 dB gain is more than enough for HF comes from Gajendra Kumar (VU2BGS). As a new "designer," I am often overwhelmed by the different possible design paths, so guidance from an elmer is crucial. It seems even MMBT2222A should work for building a HF LNA! ...
The wspr_spread work is excellent. Doppler Spread It helped us debug why our TCXO-powered-WSPR beacon was pretty decent on 4m band but flaky on 2m. Doppler spread value on 70 MHz: ... 70.0924994 VU3CER MK68 23 0 0.29 1 1 0 1 44 1 810 0.517 Now see the problem on 144 MHz: ... 144.4905417 VU3CER MK68 23 -3 0.12 1 1 0 1 39 1 810 0.865 ...
Our WSPR beacon design works fine even on the 4m band (~70 MHz) . The key is to use a 25 MHz high-quality TCXO, like the 25 MHz HCI 0.5ppm TCXO! Results Challenges 2m WSPR is still out of reach for now - see the following sporadic decodes. Of course, the next challenge is to get 2m WSPR beacons working 100% reliably at a low cost. ...
The usage of ready-made coupled inductors in RF designs was pioneered by Jim Veatch in his award-winning RF amplifier designs. Applications For Baby-QRO applications, we can use Wurth 744851330 coupled inductor. For 5W / 10W RF amplifier applications, we can use Bourns SRF1260A-4R7Y coupled inductor. Recently we were able to utilize very cost-effective YJYCOIN YPRH1207C-4R7M Chinese coupled inductor with excellent results. With our current Digital Amplifier designs, this Chinese coupled inductor works even at ~75 MHz. ...