You made the assumption that the characteristic impedance of the RF output is 50 Ohms which is incorrect. The plate of the 50C5 Oscillator from which the RF is capacitively coupled to the antenna terminal via a 470pf ceramic capacitor has a much higher impedance. The coupling capacitor alone puts the impedance somewhere north of 200 Ohms at t…[Read more]
The FCC has an online frequency search tool for LPFM that looks for channels for the licensed Low Power FM service. The search tool would also be useful for those looking for a frequency for a Part 15 station that would have minimal strong co-channel and adjacent channel signals based on location.
Here is a link to the FCC search t…[Read more]