ELECTRONIC TUNING OF TX VCOs
Original Publication Date: 1993-Oct-01
Included in the Prior Art Database: 2002-Feb-18
The schematic below shows the Transmit VCO components for a GP300 radio The coil L3 is tuned in the factory to "centre" the VCO and compensate for component variation between different VCOs. The varactor CR1 is pro- vided with a variable voltage from the synthesiser chip which alters the frequency of the VCO. An AC signal supplied by the synthesiser to CR2 allows the VCO to be modulated.