I am building a 2 transistor FM transmitter.
I have some problem in transmitting the FM signal and I believe the problem lies on the Inductor.
I am using 2 x 27pF capacitor and an inductor 0.255 uH and using this equation, i am suppose to get 84Mhz from this
but when i tune my radio to 98.30MHz I am able to listen but there are lots of noise. Now the oscillation doesnt work anymore.
So I replaced the 2 x 27pF capacitor with 2 x 47uF capacitor and the transmitter frequency changed to 118.x MHz and the voice is clear. I noticed that from the spectrum analyzer, I need to increase the capacitor capacity to bring the frequency lower so it can be in range of 88MHz and 108MHz.
I plan on buying extra capacitor for trial and error purpose but its totally different from the calculated Frequency of Oscillation.
Or is it my air coil inductor problem?? I am having a hard time to get a good air coil inductor. Any guide for me to coil a better inductor?
Please help me and replies are highly appreciated. Pardon my bad English. Thanks in advance