Ham Band VFO

This basic VFO for the 3- to 6-MHz range is commonly used in amateur applications, using a Colpitts circuit. For 5 to 5.5 MHz, C1 = C2 = 70 pF and for 3.5 to 4.0 MHz, use 1000 pF. C3 is typically 10 to 220 pF, depending on the frequency. C4, C5, and C6, together with C3, determine the frequency along with L1. C6 can be made up of several smaller values, paralleled to get the exact required value. (Reprinted with permission from Popular Electronics, 7/93, p. 80. Copyright Gernsback Publications, Inc., 1993.) From figure FE87-5 of Encyclopedia of Electronic Circuits on CD-ROM Vol. 1.