13.56Mhz quartz crystal oscillator

Thread Starter


Joined Feb 21, 2016
Attached is the circuit I built and which I'm trying to get 23dbm or 200 milliwaters of power at the output. Where I have c3 = 200p,c2=50p, and c1 = 47p cause L1 has a reactance of 250ohms and using the resonant frequency formula we get 47p for the tuner cap. Also I have 27 turns on the toroid since I'm using the t37-2 toroid, and have 12 on the secondary since I'm trying to make the 250 ohm look like 50 ohm on the output. With all that said I am not getting 23dbm but 17dbm. Can someone point me in the right direction of my problem.



Joined Aug 21, 2008
Not sure your approach is exactly the right one. Ignoring the transistor's contribution, the impedance across the tank circuit is not necessarily 250 ohms because it is a parallel tuned resonant circuit. I

I guess that your transformer's impedance ratio is not optimum.


Joined Dec 2, 2013
I do miss the feed back xtal should be between collector and base creating @ its freq 180 deg phase shift.
with one damping resistor parallel and one cap serial. This could swing collector voltage between 0 and V power depending on damping and surrounding resistors( base, collector emitter).