So if the waveform is not a sine wave it will
Produce harmonics?
Does not compute Will Robinson. (with apologies to 'Lost in space' fans). A crystal oscillator generally can't be used for FM transmission.So I built an FM transmitter not that long
Ago, I tested it with a spectrum analyzer.
I used a 100 mhz crystal oscillator. Finally got a crystal oscillator working.
Does not compute Will Robinson. (with apologies to 'Lost in space' fans). A crystal oscillator generally can't be used for FM transmission.
I'm guessing you used a crystal oscillator module, probably of the type used for clock generation so the output would be substantially a square wave. The 5V reference suggests it has TTL output. The harmonic output will be huge, you really need either low pass filter with a large out of band attenuation or better still a resonant circuit that only accepts a single frequency rather than rejecting the many unwanted ones.
Brian.
Not necessarily, but probably.so if I use a 100 mhz crystal oscillator module
It produces many harmonic frequencies?
I looked at the datasheet, the crystal oscillator module that I use, does not produce sine wave. I connected it to an antenna and a battery, making a radio transmitter. I tested it with spectrum analyzer, i saw spikes at 100 mhz and other frequencies. Would electronic filters eliminate those spikes and i only get a spike at 100 mhz?
How will you Frequency Modulate (vary the frequency) the single frequency to make FM?
Years ago, Silicon Chip magazine published The Micromitter FM stereo transmitter project and a kit for it was sold in Australia. It used a 7.6MHz crystal and electronics to make 4 radio frequencies without any harmonics. The BH1417 IC is listed at Digikey but they have none anymore.
Yes, if you do a narrow band filter for 100 Mhz that would suppress out of band mstuff.
To do a LC design - https://rf-tools.com/lc-filter/
Regards, Dana.
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Here is an example -
View attachment 159511
Regards, Dana.
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