I've checked this extremly simple concept for spurious emissions and whether they're compliant with the current regulations ...
Yesterday I've build the FROG SOUNDS 40m CW QRP transceiver.
I've ordered it as a kit from eBay Seller for about €10,- inclusive shipping to DL. The kit arrived well packed after about 15 days in my postbox.
Currently I've done 6 QSOs with the Frog and my dipole antenna.
In 2015 I've build the Frog Sounds QRP transceiver.
This little transceiver still needs improvement:
- The output is still only 400mW
- The key-click is horrible - even with the additional audio cw-filter.
- The suppresion of harmonics is very bad. Check below.
If someone has any ideas how to fix this, please Diese E-Mail-Adresse ist vor Spambots geschützt! Zur Anzeige muss JavaScript eingeschaltet sein!.
Since last weekend a new QRP transceiver joined my shack 
I bought her used from a German HAM via the QRPFORUM community. The transceiver is one of the older projects from the DL-QRP-AG but still a neat little transceiver. It is still offered in kit-form from QRP-Project in Berlin.
Here some analysis of my recorded spots data with my spot data collector. As of today there are 45.000 spots recorded in my database.
I've done some measurements on two RF detectors - one on an older diode detector from ELDITEST 
and another one on an AD8307 based one 
from SV1AFN.
My WSPR data collector is now running some days and I started with some basic data analysis.
The power on the bands 60m to 20m is about 100mW!
Inspired from some work found on the Internet and the full functionality of my U3S I've build an automatic spot collector. The spot collector pulls every 5 minutes my spots from WSPRnet.org and puts it into a MYSQL database for later analysis. See the schematic for this setup 
Alle Informationen bezüglich vna/J sind auf eine neue Webseite umgezogen:
All information regardung vna/J is moved to my new site
In case you've bricked the UNO bootloader or even the USB bootloader in the ATMEGA16U2, this may help ...
For the main power distribution in my house, I also build a powersensor. The basic idea is the same as for this sensor. But the electric meter is already build into the distribution cabinet, so this power meter uses the so-called S0 bus of the power meter inside the cabinet.
This is my first power/voltage sensor I've build. It is based on an commercially available powermeter from B+G E-Tech. You can find them on eBay or their website. It provides a 90ms pulse for each Wh flown through it.
The line voltage is measured using a simple transformer and a circuit based on the schematic from OpenEnergyMonitor. The software to measure the line voltage is also from OpenEnergyMonitor embedded into my sensor framework.
My MQTT server also has some basic systems management capabilities - means the MQTT server can emit the following data to the MQTT broker:
- CPU temperature
- Power supply temperature
- Average CPU load
- Uptime of server