This indicates that the transmitter is failing to produce adequate power or is protecting itself from damage.
[ VHF Antenna ] [ CH70 RX Antenna ] | | +-----------+-----------+ | [ FM-8900S Transceiver ] <====== [ Handset HS-2003 ] | +--------------------+---------------+-------------------+--------------------+ | | | | | [ PR-240 ] [ IF-8900 ] [ SEM-21Q ] [ IF-8500 ] [ Navigation Data ] (AC/DC Power) (Junction Box) (Loudspeaker) (Printer Interface) (GPS / NMEA0183) | | +-----+-----+ [ PP-520 Printer ] | | [ RB-8900 ] [ RC-8900 ] (Remote) (Console) fm8900s service manual
+------------------+ +------------------+ | MAIN Antenna | | CH70 RX Ant. | +--------+---------+ +--------+---------+ | | +----------v----------+ | | Antenna Switch | | | / RX-TX Relay | | +----+-----------+----+ | | | | voice/dsc| |RF Power | v v v +-----+---+ +---+-----+ +-----+-----+ | Main RX | | TX Power| | Dedicated | | Circuit | | Amplif. | | CH70 RX | +-----+---+ +---+-----+ +-----+-----+ | ^ | Demod| | Modulated | DSC | | Signal | Data v | v +-----+-----------+------------------+-----+ | MAIN BOARD | | A/D D/A Converters, Codecs, DSC Modem | | CPU & Audio Signal Processing | +-----------------+------------------------+ | v +---------+---------+ | PANEL UNIT (LCD) | +-------------------+ Receive (RX) Path This indicates that the transmitter is failing to
Months passed. Marla performed maintenance as instructed, keeping the transceiver tuned and the tapes in rotation. People on online forums started mentioning faint signals at dusk — a melody, a voice that rustled like pages. They thought it a rogue operator, a brilliant hoax. Marla read their posts without responding. She knew a different truth: some artifacts were meant to be kept in a private orbit. | | CH70 RX | +-----+---+ +---+-----+ +-----+-----+
Power Supply: Requirements for 24 VDC input and emergency battery switchover.
Reduce the generator RF output amplitude until the receiver's Sinad meter reads 20 dB. The signal input level must be less than -119 dBm (approx. 0.25 microvolts).
The FM8900S service manual is a detailed document that covers various aspects of the device. Some of the key topics included in the manual are: