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 duplex system was required. The easiset way is to use one Xtal Oscillator to feed the TX and RX but use a 450KHz I/F for RX. I used a 470KHz IFT and tuned it down to 450KHz by adjusting the slug. 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) for transmit and a 10cm wire antenna for recieve.
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This page was updated on 15th February 2000.