IF Frequencies

[Tom9589]

What is the reason that TV IF frequencies went from 26 MHZ in the early sets to 45 MHZ in the current sets. I suspect it was more than one reason.

On a tangential note, why were AM car radios' IF frequency essentially 1/2 that of table AM radios?

Curious minds want to know.

[old_tv_nut]

For one thing, it made it easier for tuners to reject the image frequencies (desired + twice IF).

It also put the local oscillator radiation out-of band for VHF.