Pages: (1) (2) (3) (4) (5) (6) (7) (8) Modulation page // Oscillator Page

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Let's continue to follow the energy though the rig. Stay here with me; you folks are walking toward the power supply and there's some capacitors over there that are charged up to 500 volts, so be careful not to touch them! They'll knock your socks off!

Old-fashioned radios used to take the amplified high frequency signal we've got now and "peel" the voice frequencies right off it. [explanation here] But newer radios first reduce the incoming frequency to an intermediate frequency. This frequency is 455 thousand cycles per second. That's quite a step down from 27 million! The reason for an intermediate frequency is that it helps your receiver give clearer reception.

That's the "why" of intermediate frequency. The "how" is that we run the signal through a mixer circuit, where we also shoot in another high frequency signal. These two signals mix together and produce a third signal, just like mixing red and blue painting will give you purple. This third frequency is the intermediate frequency. Mixing two signals like that is called heterodyning. next page -->

From The Big Dummy's Guide to C.B. Radio, courtesy of The Book Publishing Company P.O. Box 99,Summertown, TN 38483 (888) 260-8458, (1976). Editors: White Lightning (Albert Houston) WB4BWR, Stringbean WA4LXC (Mark Long), Minnesota Mumbler WB4KDH (Jeffrey Keating), Ratchet Jaw K4IAP (William Hershfield), Buffalo Bill WA4KCF (William Bradley) Illustrations by Mark Schlichting and Peter Hoyt.