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Your FM broadcast band radio is wideband. Communications is narrowband so if your radio has its frequency changed then the level of communications will be low and noise and interference will be high.

How many tuned circuits does your radio have that will need to be changed then re-aligned?
Of course the oscillator and probably an input tuned circuit. Maybe the input has a tuned circuit, and RF amplifier then a second tuned circuit. Maybe your radio uses a crystal controlled frequency synthesizer like in my home stereo and in my car radio. Then the crystal will need to be chaned and the processor's program would need changing for different channel spacing.

Instead of modifying your radios it would be better to make a down-converter circuit that uses an adjustable oscillator and an RF mixer.

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Hi Ante,
Of course a wideband FM receiver won't work on narrow band AM airplane transmissions but a down converter will allow him to hear what happens when the wrong type of radio is used.

Many years ago I made a "crystal radio" that worked very well at the airport. It had a single tuned circuit, a germanium detector diode and a sensitive amplifier.

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Before you wanted to modify a radio to higher frequencies.
Now you want to modify a transmitter to higher frequencies. Both? Why?

The site you posted talks about all the RF tuned circuits that need to be changed, then re-aligned. At least two in the radio and at least one in the transmitter.

Since you ask what happens if you remove a turn on a coil then you don't know anything about how a radio works and you probably don't have test equipment to re-align it. DON'T!

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To change the frequencies of your FM radio you need to know how many RF tuned circuits it has that need to be changed.
It has an input tuned circuit or two plus an RF oscillator tuned circuit. After increasing their frequencies then they must be aligned for matching across the whole frequency band you want.

If you use your FM transmitter on the aircraft band then you will be in big trouble!

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