Baubericht mcHF QRP-Transceiver, Teil 1

In loser Folge werde ich an dieser Stelle meine Erfahrungen beim Aufbau des mcHF QRP-Tranceivers Version 0.4 darstellen. Der mcHF ist eine Enwicklung von Chris, Rufzeichen M0NKA, und wurde maßgeblich durch die Softrock und SDRCube Projekte beeinflusst. Es handelt sich um einen SDR-Tranceiver in der Größe des KX3. [Read more...]

Flexibler Quarz-Oszillator auf Basis Si504

My first real transmitter 80m DIY Transceiver were centered around a Si570 as the oscillator and a class E power amplifier. Efficient operation was a major goal. While a class E power amplifier does give 80+% efficiency during transmit the same cannot be said for the oscillator portion. The Si570 covers an impressive frequency range: Even the least capable chip in the Si570 line can be operated between 3.5 ~ 210MHz. This unfortunately comes at the cost of high power consumption. The Si570 takes a fairly steady 90+mA at 3.3V. Another disadvantage is that the Si570's officially guaranteed frequency range just starts at 10MHz. It works down to 3.5MHz but the chip then operates out of spec. Lower frequencies (160m band, LF, VLF) require external frequency divider circuits. [Read more...]