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.

Regular supporter of wikimedia