Last year I've build the cheap Frog Sounds QRP Transceiver. This transceiver has a pretty basic audio section - a simple LM386 audio amplifier with some LC/RC filtering.
Here are the first pictures of my KiwiSDR setup ...
I've build the original QRP-labs U3S from stock. Means the supplied crystal on the PLL-based synthesiser-board.
This configuration is basically working up to 20m with a lot amount of drift, but you will get many decodes on wsprnet.org. On 6m you can also get spots - once a day :-/
In this post I describe in details, how you can create the calibration factors for k0 ... k3 based on raw data measured with the power sensor.
Ich habe das Leistungsmessmodul von Oliver, DG7XO nachgebaut. Es wurde in zwei Versionen in der cqDL vorgestellt. Oliver hat mir freundlicherweise eine Platine geätzt und den AVR programmiert, so dass nur noch Löten und Mechanik angesagt war...
I made some measurements using my miniVNApro with a simple test fixture fittig the QRP labs lowpass filters.
Measurement of the signal quality of QRP-Labs U3s with low-pass filters.Transmitter output is fed into a homemade 40dB power pad. The spectrum is measured using an SIGLENT SSA3021X analyzer.
The bias voltage was about 2.6VDC and the PA voltage was abt. 7VDC.
2014 CW (Morse Telegraphy) was added to the German Nationwide Inventory of Intangible Cultural Heritage.
© 2021 Dietmar Krause, DL2SBA