PLL based FM Tx

Nigel Goodwin said:

There have been overtone crystals in the past that operated directly at 145MHz, for 2m band transmitters without multipliers.

However, it was never a good idea, and the more normal method was to use a 12MHz one and multiply it 12 times - this also enables you to get decent NBFM whilst using a crystal.

Any remotely modern method though uses a PLL, with a free running LC oscillator locked to a much lower frequency crystal.

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mvs sarma said:

they are sold even today

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ccurtis said:

I once used a CD4046 PLL to make a stable 146 Mhz FM transmitter. The VCO section of the CD4046 is unused. <..> works for small FM deviations, say up to +/-10 Khz, and has the stability on the order of a crystal oscillator..

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