Hello
So now that I have a decent oscilloscope I've been experimenting
with higher frequency colpitts oscillators.
I've breadboarded the following arrangement (with lower RC values in the tank circuit)
I get a nice 50Mhz sine wave (after a few hours of tuning) and I have a few questions after my experimentation:
1) How can I tell if I'm emitting illegal amounts of RF radiation? (I don't have an antenna attached)
2a) I'm probing at the collector so is the actual frequency of oscillation (without the probes attached) higher by a few Mhz?
2b) How do I avoid adding that probe capacitance to the circuit? A buffer stage? That adds capacitance to the first stage aswell.
3)I'm using 5 turns of insulated 25 guage wire as the inductor with turn diameter of about 1cm. When I squash the coil together the frequency goes down and vice versa. Does squashing it together increase parasitic capacitance or the inductance?
Thanks in advance
So now that I have a decent oscilloscope I've been experimenting
with higher frequency colpitts oscillators.
I've breadboarded the following arrangement (with lower RC values in the tank circuit)
I get a nice 50Mhz sine wave (after a few hours of tuning) and I have a few questions after my experimentation:
1) How can I tell if I'm emitting illegal amounts of RF radiation? (I don't have an antenna attached)
2a) I'm probing at the collector so is the actual frequency of oscillation (without the probes attached) higher by a few Mhz?
2b) How do I avoid adding that probe capacitance to the circuit? A buffer stage? That adds capacitance to the first stage aswell.
3)I'm using 5 turns of insulated 25 guage wire as the inductor with turn diameter of about 1cm. When I squash the coil together the frequency goes down and vice versa. Does squashing it together increase parasitic capacitance or the inductance?
Thanks in advance