I want to increase the frequency of the crystal oscillator oscillating at 25MHz frequency. For this, I added an LC tank circuit to the collector in parallel with each other. I experimented to see if the frequency would change.
But, even though I tried many times for capacitor and coil values, the frequency never changed. The amplitude changed, but the frequency remained 25MHz. Why did the frequency not change? Where am I going wrong? Here is the circuit I designed.
I replaced the coil in the collector with a coil with 3 or 5 turns of winding. But, still the frequency did not change. I played with the capacitor values, and the frequency did not change. When I removed the capacitor from the tank circuit, it oscillated again at 25MHz without any change in the signal. The presence or absence of the capacitor did not change the result. Below is an article about this method.
In the article in the link, the crystal oscillator increased its frequency to 2 or 3 times. How did he achieve this? I built a similar circuit. But, I could not increase the frequency. In the circuit in the article, using an inductance at the emitter, your circuit. I added a coil to the emitter, but still the result did not change.
Maybe someone can't open the article. I am attaching a picture from the article.
Although I soldered the circuit on the PCB, I could not increase the frequency.
@Tony Stewart EE75 @glen_geek
I have done trial and error many times. I changed the eelman values of many circuits. I have been dealing with this for 1 month. No result.I read whatever I found on the internet to see if something was missing. I even have a lot of information about the history of frequency.The fact that the real experiments do not match with the ones in the books makes me very tired. It is very easy to say "look, this experiment gave this result" in simulation. It makes me sad that I can't set up the circuit and get results from the experiments.
edit:17/02/2022 I built the circuit on a perforated plate and soldered it. In the tank circuit, I used 1uH coil and 10pF capacitor. In this case, the oscillation frequency of the LC tank circuit is 50Mhz. But 50 Mhz oscillation did not occur. The output is still 25 Mhz. Therefore, soldering the circuit did not work either.