LO board provides all oscillator signals needed for signal conversion and mixing. The board consists of the following components:
– LO first oscillator realized by U2 – SI570 (570CAC000141DG), 3 switchable low pass filters: 10.8-15MHz; 15-24MHz; 24-39MHz. Filter switching is performed by I2C chip PCA9536
– 9MHz generators – U3 (SI5351) BFO, CW sidetone, beeps, U1 (SA-612) balanced mixer which acts as CW/SSB monitor product detector, digital poteniometer – U7 (MCP4018-502E)
– Tone shaping, (tones on/off ) circuitry – T1,T2,T5
– Temperature compensation oven made by thermo resistor R14 and T3,T4
PCB component side
In order to achieve good results with low harmonic content and stability – PCB board is well shielded in two component metal tin can:
