DiSEqC-Switch DIGITAL Telecom DT-2000

Schematic diagram:

This schematic solution does not use PIN-diodes. Usually PIN-diodes are used for the high frequency commutation, but in this schematic diagram the signals from LNBs are mixed, when more than one LNB will work simultaneously. It is possible if one of ports is faulty (after short circuit for example during hot-connecting). The yellow fields at the diagram define parts, that are not populated in the PCB.

Front-ends from old satellite receivers can be used for building own sat-finder for example.

TBCE18210WM

Dual input front-end with 3-wire serial interface. The interface is simple but non-standard, similar with SPI. PLL is LC7215 clocked at 11.16MHz. Reference frequency is selectable from range: 1kHz, 5kHz, 9kHz or 10kHz. The prescaler uPB1505 (with division coefficient equal 128) is on an input of a PLL. Minimum frequency step equal 128kHz, 640kHz, 1.152MHz or 1.28MHz. FM-demodulator - TDA8012.

TBCE18117IN

Front-end with 2-wire serial interface (I2C). Used PLL-synthesizer TSA5055. Pin ADDR (P3 by datasheet) defines logical address of TSA5055. Minimal frequency step is 125kHz (if sinthesizer clock is 4MHz). FM-demodulator - TDA8012. This front-end is very good for building an own sat-finder using MCU (AVR, PIC,..).

Sharp H77G08 (SG492VA-A)

Front-end is intended for the using with external PLL-synthesizer (BU2611 with clock 5.625MHz). Varicaps voltage is 24V. Front-end has the prescaler IC with marking "12079". FM-demodulator - Sharp IX1475PA.