Varactor Capacitance vs Voltage Chart

Chart is taken from the article "Tuning-Diode Applications and a VVC-Tuned 40-m VFO", by Doug DeMaw, W1FB, QST, September 1987, Page 26. The chart represents the values for a MV2109 tuning diode. This article describes a VFO using Varactor Tuning with a Temperature Compensation Diode using a 2N3904. A Motorola application note says that the 2N3904 to be one of the best compensation parts for the low capacitance tuning diodes. Stability using this compensation diode (2N3904 using base and collector only) is excellent.