Description We have built a Bluetooth-enabled and APRSdroid-compatible digital interface (KISS TNC) for less than 15 USD (for the fully-loaded make including cables). We call it the KISSLink v1. This digital interface can be powered from the USB 5V or the inbuilt battery. Schematic Previous Next / [pdf] View the PDF file here. RX path simulation (AF front-end) ...
Setup: Si5351 RF generator (@ 28 MHz) ➔ GSD-Hacks-v5 digital amplifier ➔ 7th order LPF ➔ {COAX-UNDER-TEST} ➔ Digital RF power meter ➔ Dummy load Results Results at 13.8V drain: Coax Type Power Reading RG-58 (7 meters) 4.5W RG-316 (7 meters) 3.9W RG-188 (7 meters) 3.9W Results at 15V drain: Coax Type Power Reading RG-58 (7 meters) 5.4W RG-316 (7 meters) 4.7W RG-188 (7 meters) 4.7W These measurements appear to match those from Eric, WD8RIF. ...
My solar powered WSPR beacon is now active on the 12m band! Tech Stack Tech stack: Navitas 100W Solar Panel, Exide Solar Blitz 40AH battery, Skypearll Solar Charge Controller 30A, 200W 20A DC-DC CC CV Buck module (Robu) - set to output 7.5V, Waveshare ESP32-S3 Zero board, Si5351 with 0.5ppm TCXO, GSD-Hacks-v5 amplifier, DFRobot Gravity Digital 5A Relay Module Photos of components involved (for reference): ...
For HF and amateur VHF bands our WiFi VFO works great. But we didn't have a cost-effective UHF signal source until now… Design Thanks to Ismo (OH2FTG), we recently experimented with a HopeRF CMT2119A powered board called HOPERF RF module RFM119W-433S1. Here is the CMT2119A powered board in action producing a CW (OOK) signal at ~433 MHz. The stability is pretty good and a bit surprising considering that the board uses a 20ppm 26 MHz regular quartz crystal - not bad! ...
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 ...
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. ...
Our 6m WSPR beacon design works fine now. The key is to use a 25 MHz high-quality TCXO, like the 25 MHz HCI 0.5ppm TCXO! 2m WSPR is still out of reach for this VFO design - see the following drifty screenshots: While WSPR is no good, 2m FT8 works pretty fine! ...
We make heavy use of Easy-Digital-Beacons-v1 for testing RF amplifiers. This single board is a versatile WiFi VFO and FT8 / FT4 / WSPR beacon. You can also use our CW-SigGen project to generate a suitable test signal.