Full Duplex Transceiver

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This NBFM VHF transceiver was orginally designed for a work collegue Mr. Paul Creed, who wished to have a radio link between himself and his son whilst riding his motorcycle and son in the side car. As it is difficult to use a PTT on a motorbike a continuous transmission / reception system was required. The easiset way is to use one Xtal Oscillator to feed the TX and RX but use a 450KHz I/F RX. The chosen frequencies were 49.860MHz for one unit and 49.410MHz for the other. These units will output approximately 10mW of RF power and ranges of 300ft have been achieved using a 1/6wave rubber duck (144MHz R/D works well). All single wound coils are of 7turns open air 7mm di. IFT1 is a 455 I/F Transformer and the Transformer type coil is 6turns over 7turns on a 10mm core.