how to make a frequency multiplier without pll..?

Question

anonymous · Answer

using varactor diodes spark gap transmitters or arc converters

anonymous · Answer

One common method for frequency multiplication is to overdrive a transistor amplifier.  If you purposely drive the transistor into the nonlinear regions of the collector current-gain curve, then you'll get 3rd and 5th harmonics on the output.

If you don't need a variable frequency multiplier, then you can do something similar with a crystal oscillator.   If you operate a crystal in overtone mode (overdriven), then you can get harmonics from it; however, they are very specifics frequencies since a crystal is tuned for a certain frequency.