it is not 1F, it is IF (intermitent frequency).
Take a look at this page to see what do they look like
(top page) **broken link removed**
4.5MHz is IF frequency for video signal and it's found in TV sets.
If you cannot source new device from your electronic supplier,
just salvage components from broken TV. Note that it's not look
or size that count, it's the resonant frequency. This means you
cannot just use same thing from an AM/FM radio and expect your
transmitter to work correctly.